US4636212A - Ultraviolet radiation absorbing intraocular lens - Google Patents

Ultraviolet radiation absorbing intraocular lens Download PDF

Info

Publication number
US4636212A
US4636212A US06/713,014 US71301485A US4636212A US 4636212 A US4636212 A US 4636212A US 71301485 A US71301485 A US 71301485A US 4636212 A US4636212 A US 4636212A
Authority
US
United States
Prior art keywords
test
ultraviolet radiation
lens
intraocular lens
polymer
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
US06/713,014
Inventor
Thomas Posin
Daniel D. Lawson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Optical Radiation Corp
Original Assignee
Optical Radiation Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Optical Radiation Corp filed Critical Optical Radiation Corp
Priority to US06/713,014 priority Critical patent/US4636212A/en
Assigned to OPTICAL RADIATION CORPORATION, A CORP. OF CA. reassignment OPTICAL RADIATION CORPORATION, A CORP. OF CA. ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: LAWSON, DANIEL D., POSIN, THOMAS
Priority to US06/948,328 priority patent/US4753654A/en
Application granted granted Critical
Publication of US4636212A publication Critical patent/US4636212A/en
Assigned to EUROPEAN AMERICAN BANK, NATIONSBANK, N.A., NATIONSBANK, N.A., AS AGENT*, NATIONAL CITY BANK, KENTUCKY reassignment EUROPEAN AMERICAN BANK SECURITY AGREEMENT/COLLATERAL ASSIGNMENT Assignors: OPTICAL RADIATION CORPORATION, OPTICAL RADIATION CORPORATION
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Images

Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/02—Prostheses implantable into the body
    • A61F2/14—Eye parts, e.g. lenses or corneal implants; Artificial eyes
    • A61F2/16—Intraocular lenses
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L27/00—Materials for grafts or prostheses or for coating grafts or prostheses
    • A61L27/14—Macromolecular materials
    • A61L27/16—Macromolecular materials obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L27/00—Materials for grafts or prostheses or for coating grafts or prostheses
    • A61L27/50—Materials characterised by their function or physical properties, e.g. injectable or lubricating compositions, shape-memory materials, surface modified materials
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/02—Prostheses implantable into the body
    • A61F2/14—Eye parts, e.g. lenses or corneal implants; Artificial eyes
    • A61F2/16—Intraocular lenses
    • A61F2002/16965—Lens includes ultraviolet absorber
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F2250/00—Special features of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
    • A61F2250/0058—Additional features; Implant or prostheses properties not otherwise provided for
    • A61F2250/0096—Markers and sensors for detecting a position or changes of a position of an implant, e.g. RF sensors, ultrasound markers
    • A61F2250/0098—Markers and sensors for detecting a position or changes of a position of an implant, e.g. RF sensors, ultrasound markers radio-opaque, e.g. radio-opaque markers
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L2430/00—Materials or treatment for tissue regeneration
    • A61L2430/16—Materials or treatment for tissue regeneration for reconstruction of eye parts, e.g. intraocular lens, cornea

Definitions

  • This invention relates to an intraocular lens capable of absorbing ultraviolet radiation and, additionally, to a method for forming the lens.
  • the problem of restoring useful vision to a human eye after its cataractus natural lens has been removed has been with us since the introduction of cataract surgery.
  • the solution to this problem has included the use of spectacle lenses, contact lenses, and permanent implantation into the eye of a man-made lens, i.e., an intraocular lens.
  • PMMA polymethylmethacrylte
  • the cornea and crystalline lens work together to absorb ultraviolet radiation or light.
  • the cornea absorbs virtually all of the ultraviolet radiation below 300 nanometers (nm) that reaches the eye (almost all ultraviolet radiation below 286 nm is absorbed by the ozone layer in the earth's atmosphere).
  • the cornea also absorbs a portion of the ultraviolet radiation between 300 nm and 400 nm, the natural crystalline lens absorbs the major portion of the ultraviolet radiation in this range.
  • ultraviolet radiation is considered by many opthamologists as a casual factor in erythropsia ("pink vision"), cystoid macular edema, and macular degeneration.
  • polymethylmethacrylate does not absorb any significant portion of the ultraviolet radiation in the 300-400 nm range, persons who have had a polymethylmethacrylate intraocular lens implant have been prone to retinal damage from ultraviolet radiation or have had to protect their pseudophakic eye by using spectacle lenses having ultraviolet light absorbing capability.
  • an intraocular lens that has ultraviolet absorbing capabilities, firstly to protect the retina of the eye from radiation damage, and secondly to retard damage to the intraocular lens itself from such ultraviolet radiation. It is desired that the ultraviolet absorbing intraocular lens have absorbing capabilities which approximate the capabilities of the natural crystalline lens which has been removed. Further, the ultraviolet absorbing intraocular lens may be biocompatible with body fluids and tissue and have desired optical properties.
  • the intraocular lens comprises an ultraviolet radiation absorbing co-polymer physically trapped within a polymer matrix, such as polymethylmethacrylate for example.
  • the ultraviolet absorbing co-polymer is formed by co-polymerizing a polymerizable derivative of dihydroxybenzophenone with a monomer suitable for making intraocular lenses, e.g., methyl methacrylate.
  • the intraocular lens is biocompatible with body tissue and fluids and has about the same capability for absorbing ultraviolet radiation as does the natural crystalline lens of the eye.
  • the ultraviolet radiation absorbing intraocular lens is formed by co-polymerizing a polymerizable derivative of 2,4-dihydroxybenzophenone and methyl methacrylate monomer to form an ultraviolet radiation absorbing co-polymer additive.
  • the ultraviolet radiation absorbing co-polymer additive is mixed with methyl methacrylate monomer for forming a prepolymer solution.
  • the prepolymer solution is cured to form the ultraviolet radiation absorbing intraocular lens.
  • FIG. 1 is a plan view of an exemplary intraocular lens assembly comprising a lens having an ultraviolet radiation absorbing capability provided in accordance with practice of this invention.
  • FIG. 2 is a side view of the exemplary intraocular lens assembly of FIG. 1.
  • FIGS. 1 and 2 there is shown a plan view (FIG. 1) and a side view (FIG. 2) of an intraocular lens assembly 10 for implantation into the human eye provided in accordance with practice of principles of this invention.
  • the intraocular lens assembly 10 comprises one or more non-optical "haptic" components 12 connected to an optical component or lens 14.
  • the haptic components are useful for supporting or attaching the lens to an aphakic eye.
  • the lens 14 comprises an ultraviolet radiation absorbing co-polymer physically trapped within a polymer matrix for example, of polymethylmethacrylate.
  • the ultraviolet radiation absorbing co-polymer is formed by co-polymerizing a polymerizable chromophoric compound for example, a polymerizable derivative of dihydroxybenzophenone, with a monomer suitable for making such lenses, for example, with methyl methacrylate.
  • the resulting intraocular lens preferably has about the same capability for absorbing ultraviolet radiation as does the natural crystalline lens of the eye and is biocompatible with body tissue and fluids.
  • the lens 14 of the assembly 10 is a "planoconvex lens", i.e., it has a convex surface 16 on one side and a flat or planar surface 18 on its other side, lenses having any desired design configuration can be provided.
  • two haptics 12 are shown, fewer or more haptics can be used as desired and the haptics can have configurations other than the configuration of the haptics shown in the exemplary embodiment.
  • the lens 14 preferably is formed in a series of steps which include co-polymerizing the selected polymerizable chromophoric compound with methyl methacrylate monomer to form an ultraviolet radiation absorbing co-polymer additive; dissolving the ultraviolet radiation absorbing co-polymer additive in methyl methacrylate monomer to form a prepolymer solution; curing the prepolymer solution; and finishing the lens as necessary from the cured prepolymer.
  • Exemplary chromophoric compounds useful in practice of this invention are ethylenically unsaturated derivatives of dihydroxybenzophenone selected from the group consisting of: ##STR1## wherein X is an ethylenically unsaturated radical selected from the group consisting of acryloxy beta-hydroxypropyl and methacryloxy beta-hydroxypropyl radicals and wherein R represents a radical selected from the class consisting of hydrogen and hydroxy radicals.
  • dihydroxybenzophenone derivatives useful in practice of this invention, there may include derivatives of 2,4-dihydroxybenzophenone such as 4-acryloxy beta-hydroxypropyl ether of 2,4-dihydroxybenzophenone; the 4-methacryloxy beta-hydroxypropyl ether of 2,4-dihydroxybenzophenone, i.e., 2-hydroxy-4-(2-hydroxy-3-methacrylyloxy)propoxybenzophenone; the 4-acryloxy beta-hydroxypropyl ether of 2,2',4-trihydroxybenzophenone; the 4-methacryloxy beta-hydroxypropyl ether of 2,2',4-trihydroxybenzophenone; the 4,4'-di(acryloxy beta-hydroxypropyl) ether of 2,2',4,4'-tetrahydroxybenzophenone; and the 4,4'-di(methacryloxy beta-hydroxypropyl) ether of 2,2',4,4'-tetrahydroxybenzophenone.
  • 2,4-dihydroxybenzophenone
  • chromophoric compounds may also be used such as allylic substituted benzophenones, i.e., 2-hydroxy-3-allyl-4,4' dimethoxybenzophenone, ethylenically or allylically substituted phenyl benzotriazoles, provided that they are capable of readily undergoing vinyl-type polymerization reactions and thus can form a co-polymer with methyl methacrylate monomer.
  • allylic substituted benzophenones i.e., 2-hydroxy-3-allyl-4,4' dimethoxybenzophenone, ethylenically or allylically substituted phenyl benzotriazoles
  • the chromophoric compound is a material sold by National Starch and Chemical Corporation, Resin Division, Bridgewater, N.J., under the trademark PERMASORB MA.
  • PERMASORB MA is represented by National Starch to include 2-hydroxy-4-(2-hydroxy-3-methacrylyloxy)propoxybenzophenone, which has the following chemical structure: ##STR2##
  • methyl methacrylate monomer and PERMASORB MA are dissolved in dry ethyl acetate to form a "monomer mix".
  • An "initiator mix” is prepared by dissolving an initiator in dry ethyl acetate.
  • initiators are benzoyl peroxide, tert-butyl hydro peroxide, cumene hydro peroxide, 2-azobisisobutyronitrile, and azoisobutylnitrile (AIBN) and the like.
  • the monomer mix and initiator mix are mixed together in a reaction flask and heated to reflux at about 77° C. ⁇ 3° C. for a period of time to form the co-polymer of methyl methacrylate and PERMASORB MA co-polymer).
  • the reaction mixture is then cooled and added to 5 to 6 times its volume of anhydrous methanol which causes the ultraviolet radiation absorbing PMMA/PERMASORB MA co-polynmer to precipitate as a solid polymer mass.
  • the ultraviolet radiation absorbing solid polymer mass is comminuted, i.e., ground into a fine powder, and dried.
  • the comminuted co-polymer is purified by "Soxhlet" extraction to remove remaining unreacted raw materials and solvents.
  • the solid co-polymer is then vacuum dried and comminuted.
  • the comminuted co-polymer (the ultraviolet radiation absorbing PMMA/PERMASORB MA co-polymer additive) is dissolved in methyl methacrylate monomer to form a prepolymer solution and the prepolymer solution is cured to form the ultraviolet radiation absorbing intraocular lens of this invention wherein the PMMA/PERMASORB MA co-polymer is trapped within the polymethylmethacrylate matrix of the lens.
  • the prepolymer solution can be poured into a mold having a desired optical configuration.
  • the mold after it is filled, is then placed into an autoclave and subjected to elevated temperature and pressure conditions for curing the lens.
  • the mold After completion of the desired time-temperature/pressure cycle in the autoclave, the mold is removed therefrom and the lens blank is removed from the mold.
  • the edges are then removed from the lens blank by machining and haptics are connected to the lens in appropriate holes formed in its edges. After the haptics are attached, the finished intraocular lens is inspected, sterilized, and packaged for shipment.
  • the ratio of the weight of the chromophoric compound to the total weight of chromophoric compound plus methyl methacrylate monomer in the monomer mix is small enough so that the co-polymer formed, i.e., the co-polymer additive, is soluble in polymethylmethacrylate. This is important so that the finished intraocular lens has a desired optical clarity.
  • the ratio of the weight of PERMASORB MA to the total weight of PERMASORB MA plus methyl methacrylate monomer in the monomer mix is such that, upon polymerization of the monomer mix, less than about 15 percent by weight of the PMMA/PERMASORB MA co-polymer additive formed comprises PERMASORB MA.
  • the PMMA/PERMASORB MA co-polymer comprises less than about 15% by weight PERMASORB MA because it has been found that when such a co-polymer additive comprises a higher weight percentage of PERMASORB MA, the co-polymer is not soluble at any proportion in polymethylmethacrylate. Thus, lenses formed using PMMA/PERMASORB MA co-polymer additive comprising more than about 15% by weight PERMASORB MA tend to be cloudy or hazy.
  • lenses formed using PMMA/PERMASORB MA co-polymer additives comprising 16.1 %, 22.5%, and 50% by weight PERMASORB MA all produced hazy lenses, while lenses formed of PMMA/PERMASORB MA co-polymer additive comprising 5.7%, 10%, and 12% were clear. Surprisingly, this appears to be the case regardless of the weight ratio of PMMA/PERMASORB MA co-polymer additive to MMA monomer used to form the PMMA/PERMASORB MA intraocular lens.
  • the finished lens comprises from about four percent to about five percent by weight PERMASORB MA.
  • an initiator mix was prepared by dissolving 1 gram of azoisobutylnitrile (AIBN) at room temperature in 25 grams of dry ethyl acetate.
  • AIBN azoisobutylnitrile
  • the co-polymer was then filtered and extracted in methanol with a Soxhlet extractor using a cellulose thimble. After methanol extraction, the co-polymer blob was placed in a blender with methanol and again a fine suspension of the co-polymer was formed. The suspension was filtered and, to remove any cellulose fibers from the co-polymer, the filtered co-polymer blob was placed in methylene chloride (CH 2 Cl 2 ) and dissolved. The methylene chloride/co-polymer solution was then filtered and the co-polymer was reprecipitated from the filtered solution in methanol. The co-polymer (the PMMA/PERMASORB MA co-polymer additive) was then dried and ground into a fine powder.
  • methylene chloride CH 2 Cl 2
  • the prepolymer solution about 30 percent by weight of the co-polymer powder (the PMMA/PERMASORB MA co-polymer additive) was placed into a reaction flask with about 70 percent by weight methyl methacrylate monomer. The monomer/co-polymer mixture was stirred for about 14 hours at room temperature to dissolve the powder. Benzoyl peroxide initiator was added (0.05% by weight based on the weight of methyl methacrylate monomer) and mixed into the prepolymer solution for about 30 minutes at room temperature. The prepolymer solution was then subjected to a vacuum process to remove any dissolved gases and air bubbles.
  • the co-polymer powder the PMMA/PERMASORB MA co-polymer additive
  • the degassed prepolymer solution was filtered through a 5 micron filter as it was being poured into a mold for curing.
  • the mold was then placed into a casting chamber and subjected to conditions of temperature, pressure, and time for polymerizing or curing the prepolymer solution to form a solid polymeric ultraviolet radiation absorbing material comprising the ultraviolet radiation absorbing co-polymer additive physically trapped within a polymethylmethacrylate polymer matrix.
  • An intraocular lens provided in accordance with this invention is finished from the ultraviolet radiation absorbing polymeric material by machining and other appropriate lens finishing operations.
  • a device that is to be implanted in the body is biocompatible with body tissue and fluids, i.e., it does not produce adverse local or systemic responses or cause sensitization leading to an allergic response when implanted.
  • FDA Food and Drug Administration
  • the amount of MMA monomer that leaches from materials prepared in accordance with Example 1 was determined by measuring the amount of MMA monomer in such a material before and after a 24-hour saline extraction.
  • UVI-EXPOSED Three cast sheets of test material were subjected to ethylene oxide sterilization. The three sample sheets were then divided into two parts each and labeled as follows: UVI-EXPOSED, UVI-UNEXPOSED, UVII-EXPOSED, UVII-UNEXPOSED, UVIII-EXPOSED, and UVIII-UNEXPOSED.
  • % MMA monomer was measured by dissolving the entire piece of material in acetone and performing a gas chromatograph (GC) analysis for MMA monomer content.
  • GC gas chromatograph
  • the method used to perform the GC analysis was similar to Galin, M. A. et al; Methyl Methacrylate Monomer in Intraocular Lenses of PMMA; Arch. Opthalmol, Vol. 98, January 1980, pp 120-121. All other sample pieces were placed into separate glass containers filled with USP saline solution for extraction at 37 ⁇ 4° C.
  • the amount of MMA monomer that leaches from materials prepared in accordance with Example 1 was determined by measuring the amount of MMA monomer in saline extract during a 21-day saline extraction.
  • UVIA-EXPOSED Three cast sheets of test material were subjected to ethylene oxide sterilization. The three sample sheets of test material were then divided into two parts each and labeled as follows: UVIA-EXPOSED, UVIA-UNEXPOSED, UVIIA-EXPOSED, UVIIA-UNEXPOSED, UVIIIA-EXPOSED, and UVIIIA-UNEXPOSED.
  • Each of the six labeled test material sample parts were then divided into smaller pieces for subsequent sampling.
  • a representative piece of each sample part was removed for % MMA residual monomer analysis.
  • % MMA monomer was measured by dissolving the entire piece of test material in acetone and performing GC analysis for MMA monomer content.
  • All other sample pieces of test material were placed into separate glass containers filled with USP saline solution for extraction at 37 ⁇ 4° C. (similar to the environment within the natural eye).
  • Representative extract samples were removed at various time periods throughout the 21-day extraction, i.e., days 4 through 7, days 12 and 13, and days 19 and 20, and subjected to GC analysis for determination of % extracted MMA monomer.
  • the ratio of aqueous to acrylic was 30 to 1.
  • test material The amount of PERMASORB MA that leaches from materials prepared in accordance with Example 1 (test material) was determined by subjecting such test materials to 20 days saline extraction and then measuring the before and after UV transmission of the extract.
  • Example 3 The test of this Example was run in conjunction with Example 3 described above. However, subsequent to the initiation of the extraction time period, the following procedure was followed: Representative sample test material pieces and extract samples from each glass container were removed at various time periods throughout the 21-day extraction, i.e., days 4 through 7, days 12 and 13, and days 19 and 20. For each test material sample removed, its thickness and % UV transmission were measured. For each extract sample removed, a measurement of the % UV transmission was performed. The UV spectrophotometer is repeatable to ⁇ 1% providing a method that can reliably quantify 2.2 ppm PERMASORB MA. The sensitivity of the instrument is 0.7 ppm.
  • Tables 3 through 8 contain the results of these studies (excluding the results of the HPLC determination).
  • the PERMASORB MA was being extracted, increased absorption of the saline extract solutions would be anticipated.
  • increased transmission of the test material samples would be anticipated.
  • neither of these two observations occurred with any significance.
  • the difference in % UV transmission can be attributed to the accuracy ( ⁇ 1%) of the UV spectrophotometer.
  • test material Eight (8) samples of cast material prepared in accordance with Example 1 (test material) were used. Four of the eight (8) samples of test material were sterilized by ethylene oxide sterilization.
  • test material samples were placed in a 10 ml vial and then dissolved in HPLC grade acetone for 24 hours at room temperature. All sample vials were sealed with a teflon septum. (Note: To accelerate solution, some samples were subjected to ultrasonification at 65° C. This was sometimes necessary due to the degree of cross-linking.)
  • Example 1 To determine if photodegradation of material prepared in accordance with Example 1 (test material) could occur, such materials were subjected to high dosage ultraviolet radiation. The materials were subjected to two levels of exposure; the first level was equivalent to 7.8 years of normal eye exposure to UV radiation and the second level was equivalent to 14.5 years. The UV radiation exposed samples were evaluated for any increase in residual MMA monomer, changes in their UV transmission characteristics, and the extent, if any, of changes in PERMASORB MA and MMA leachability rates compared to non-UV exposed control material.
  • the results of the 7.8 year and 14.5 year ultraviolet exposure tests showed no changes between the before and after exposed test material samples.
  • the residual monomer in the samples both before and after exposure were the same; the ultraviolet transmission of the material before and after exposure to high dosages of UV radiation remained unchanged; and there was no difference in the monomer leachability, i.e., none detected, on the before and after exposure samples.
  • the same results were found with regard to the PERMASORB MA leachability of the samples, i.e., none detected.
  • Example 2-7 In addition to the analytical tests set forth in Examples 2-7, which indicated that leaching is not a problem, various in-vivo and in-vitro biological tests were conducted by an independent testing laboratory on materials prepared in accordance with Example 1 to confirm that such materials are biologically compatible with body tissue and fluids.
  • mice Healthy, young, white mice ranging in body weight from 17 to 23 grams were injected either intraveneously or intraperitoneally with one of four different extracts (saline, alcohol/saline, polyethylene glycol 400, and cottonseed oil) of a material prepared in accordance with Example 1.
  • the extracts were prepared at 121° C. for one hour. Two groups, each consisting of five mice, were used for each extract. One group was injected with the extract of the test material, while the other group was injected with a blank. After injection, the animals were observed immediately and at 4, 24, 48, and 72 hours. Initial and final body weights were recorded, as well as mortalities and/or reactions. If, during the observation period, none of the animals treated with the extract of the test material show a significantly greater reaction than the animals treated with the blank, the material meets the requirements of the test. The results of the tests are recorded in Table 11.
  • extracts saline, alcohol/saline, polyethylene glycol 400, and cottonseed oil
  • a microscopic evaluation of the implanted tissue was also conducted 7 days after implantation following routine staining of the tissues with Hematoxylin and Eosin. Tissue reactions were recorded for inflammation, chronic irritation, foreign body response, tissue scarring, and necrosis. The results of the microscopic evaluation are listed in Table 14.
  • test material prepared in accordance with Example 1 is a non-irritant.
  • Extracts of material prepared in accordance with Example 1 were injected into the anterior chamber of the eyes of a number of rabbits to determine the irritation or toxicity potential of the extracts.
  • Rabbits were anesthetized by intramuscular injection of Acepromazine/Ketamine HCl combination (61 mg/ml) given at a dose of 0.75 ml/kg body weight. Following successful anesthesia, an ocular speculum (lid retractor) was put into place. The eye was steadied by gently grasping the palpebral conjunctiva with a pair of fine-toothed forceps. A 1 cc syringe containing test or control extract and attached to a 27 g needle was introduced into the anterior chamber of the eye. The needle was inserted about 0.5 cm into the anterior chamber at the corneal-scleral junction and parallel to the iris.
  • a second syringe with 27 g needle was inserted at a remote point from the first. Approximately 0.2 ml of the aqueous fluid was evacuated immediately prior to injecting 0.2 ml of test or control extract via the first syringe. After the procedure, rabbits were returned to their cages and allowed to recover.
  • Biomicroscope slit lamp examinations were conducted prior to treatment, at day one, day three, and termination (McDonald-Shaddock score system). Control animals were examined prior to treatment and at termination. Additionally, macroscopic observations of the eyes were conducted daily (Draize System); body weights were recorded prior to treatment and at termination; and on a representative number of eyes, tonometry readings (Schiotz tonometer) were taken before and after treatments.
  • the rabbits were killed by injection of T-61 Euthanasia Drug.
  • the eyes were quickly removed and placed in 10% neutral buffered formalin for possible histological processing.
  • 0 Normal. May appear blanched to reddish pink without perilimbal injection (except at 12:00 and 6:00 o'clock positions) with vessels of the palpebral and bulbar conjunctiva easily observed (FIG. 2).
  • +1 A flushed, reddish color predominately confined to the palpebral conjunctival with some perilimbal injection, but primarily confined to the lower and upper parts of the eye from the 4:00 and 7:00 and 11:00 to 1:00 o'clock positions.
  • +2 Bright red color of the palpebral conjunctiva with accompanying perilimbal injection covering at least 75% of the circumference of the perilimbal region (FIG. 3).
  • +3 Dark, beefy red color with congestion of both the bulbar and the palpebral conjunctiva along with pronounced perilimbal injection and the presence of petechia on the conjunctiva.
  • the petechia generally predominates along the nictitating membrane and the upper palpebral conjunctiva.
  • +3 Swelling definite with partial eversion of the upper and lower eyelids essentially equivalent. This can be easily ascertained by looking at the animal head-on and noticing the positioning of the eyelids; if the eye margins do not meet, eversion has occurred.
  • Discharge is defined as a whitish, gray precipitate, which should not be confused with the small amount of clear, inspisated, mucoid material that can be formed in the medial canthus of a substantial number of rabbit eyes. This material can be removed with a cotton swab before the animals are used.
  • +1 Discharge above normal and present on the inner portion of the eye, but not on the lids or hairs of the eyelids.
  • the scoring scheme measures the severity of corneal cloudiness and the area of the cornea involved. Severity of corneal coloudiness is graded as follows.
  • 0 Normal cornea. Appears with the slit lamp as having a bright gray line on the epithelial surface and a bright gray line on the endothelial surface with a marblelike gray appearance of the stroma.
  • +2 Moderate loss of transparency.
  • the cloudiness extends all the way to the endothelium.
  • the stroma has lost its marblelike appearance and is homogeneously white. With diffuse illumination, underlying structures are clearly visible.
  • +3 Involvement of the entire thickness of the stroma. With optical section, the endothelial surface is still visible. However, with diffuse illumination, the underlying structures are just barely visible (to the extent that the observer is still able to grade flare, ulceris, observe for pupillary response, and note lenticular changes).
  • the surface area of the cornea relative to the area of cloudiness is divided into five grades from 0 to +4.
  • 0 Normal cornea with no area of cloudiness.
  • fluorescein is a valuable aid in defining epithelial damage.
  • +1 Slight fluorescein staining confined to a small focus. With diffuse illumination, the underlying structures are easily visible. (The outline of the pupillary margin is as if there were no fluorescein staining.)
  • +2 Moderate fluorescein staining confined to a small focus. With diffuse illumination, the underlying structures are clearly visible, although there is some loss of detail.
  • +3 Marked fluorescein staining. Staining may involve a larger portion of the cornea. With diffuse illumination, underlying structures are barely visible, but are not completely obliterated.
  • the intensity of the Tyndall phenomenon is scored by comparing the normal Tyndall effect observed when the slit-lamp beam passes through the lens with that seen in the anterior chamber.
  • the presence of aqueous flare is presumptive evidence of breakdown of the blood-aqueous barrier.
  • the primary, secondary, and tertiary vessels are utilized as an aid to determining a subjective ocular score for iris involvement.
  • the assumption is made that the greater the hyperemia of the vessels and the more the secondary and tertiary vessels are involved, the greater the intensity of iris involvement.
  • the scores range from 0 to +4.
  • 0 Normal iris without any hyperemia of the iris vessels. Occasionally around the 12:00 to 1:00 o'clock position near the pupillary border and the 6:00 and 7:00 o'clock position near the pupillary border, there is a small area around 1-3 mm in diameter in which both the secondary and tertiary vessels are slightly hyperemic.
  • +1 Minimal injection of secondary vessels, but not tertiary. Generally, it is uniform, but may be of greater intensity at the 1:00 or 6:00 o'clock position. If it is confined to the 1:00 or 6:00 o'clock position, the tertiary vessels must be substantially hyperemic.
  • +2 Minimal injection of tertiary vessels and minimal to moderate injection of the secondary vessels.
  • +3 Moderate injection of the secondary and tertiary vessels with slight swelling of the iris stroma (this gives the iris surface a slightly rugose appearance, which is usually most prominent near the 3:00 and 9:00 o'clock positions).
  • +4 Marked injection of the secondary and tertiary vessels with marked swelling of the iris stroma.
  • the iris appears rugose; may be accompanied by hemorrhage (hyphema) in the anterior chamber.
  • Pannus is vascularization or the penetration of new blood vessels into the corneal stroma.
  • the vessels are derived from the limbal vascular loops.
  • Pannus is divided into three grades.
  • +1 Vascularization is present, but vessels have not invaded the entire corneal circumference. Where localized vessel invasion has occurred, they have not penetrated beyond 2 mm.
  • Iritis was the significant observation noted during the macroscopic observations. As the post-operative period progressed, the ulceris diminished. At seven (7) days, the gross appearance of the majority of the eyes was similar to the non-treated control group.
  • Tonometry readings (Schiotz with standard 5.5 g wt) taken prior to and after treatment indicated that the removal and instillation of approximately equal volumes of fluid caused an immediate increase in intraocular pressure. There was some evidence that the ocular pressure had returned to normal by 7 days, but the influence of general anesthetics and/or euthanasia drug was not determined. The results of the tonometry readings are in Table 18.
  • a monolayer of L-929 Mouse Fibroblast cells was grown to confluency and exposed to an extract of a test sample prepared by placing material prepared in accordance with Example 1 (test material) in 20 ml of Minimum Essential Medium (Eagle) and bovine serum (5%) and extracting at 37° C. for 24 hours. An MEM aliquot was used as a negative control. After exposure to the extract, the cells were examined microscopically for cytotoxic effect (CTE). Cytotoxicity was scored as either Non-Toxic (N), Intermediate (I), or Toxic (T).
  • N Indicates a negative or non-toxic response
  • I Indicates an intermediate response, a subjective assessment of the extent of cellular response
  • T Indicates a positive or toxic response consisting of greater than 50% cell death.
  • a monolayer of L-929 Mouse Fibroblast cells was grown to confluency and overlaid with Medium 199 supplemented with serum, antibiotics, neutral red, and agar.
  • An intraocular lens comprising material prepared in accordance with Example 1 (test material) was placed on the solidified overlay surface. Following incubation for 24 hours, the culture was macroscopically examined for evidence of cell decolorization to determine the zone of cell lysis. Any decolorized zone present was examined microscopically to confirm cell lysis. The results are listed in Table 20.
  • test material is non-toxic for L-929 cells under the above described test conditions.
  • a monolayer of L-929 Mouse Fibroblast cells was grown to confluency and overlaid with Medium 199 supplemented with serum, antibiotics, neutral red, and agar.
  • a 1 cm 2 sheet of material prepared in accordance with Example 1 (test material) was placed on the solidified overlay surface. Following incubation for 24 hours, the culture was macroscopically examined for evidence of cell decolorization to determine the zone of cell lysis. Any decolorized zone present was examined microscopically to confirm cell lysis. The results are listed in Table 21.
  • test material is non-toxic for L-929 cells under the above described conditions.
  • Example 2 90 square centimeters of material prepared in accordance with Example 1 (test material) was placed in 30 ml of sodium chloride solution (0.9%) and extracted at 121° C. for 1 hour. The extract was divided into two tubes of 10 ml each.
  • optical density of each sample solution was determined spectrophotometrically at 545 m ⁇ . Similarly, optical densities were recorded for a positive control (10 ml water and 0.2 ml blood) and a negative control (10 ml Sodium Chloride and 0.2 ml blood). The results are listed in Table 22.
  • test material is non-hemolytic under conditions of this test.
  • test material was sterilized with ethylene oxide and cut into small chips or lengths (3 cm ⁇ 0.5 cm). 2 grams of the test material were placed in each of two extracting tubes containing 10 ml of sodium chloride solution (0.9%).
  • optical density of each sample solution was determined spectrophotometrically at 545 m ⁇ . Similarly, optical densities were recorded for a positive control (10 ml water and 0.2 ml blood) and a negative control (10 ml Sodium Chloride and 0.2 ml blood). The results are listed in Table 23.
  • test material is non-hemolytic under conditions of the test.
  • An intraocular lens comprising prepared in accordance with Example 1 (test material) was cut in half. Each half was placed in a separate extracting tube containing 10 ml of sodium chloride solution (0.9%).
  • optical density of each sample solution was determined spectrophotometrically at 545 m ⁇ . Similarly, optical densities were recorded for a positive control (10 ml water and 0.2 ml blood) and a negative control (10 ml Sodium Chloride and 0.2 ml blood). The results are listed in Table 24.
  • test material is non-hemolytic under conditions of the test.
  • Example 1 Material prepared in accordance with Example 1 (test material) was cut into small chips or lengths (3 cm ⁇ 0.5 cm) and two grams of the material was placed into each of two extracting tubes containing 10 ml of sodium chloride solution (0.9%).
  • optical density of each sample solution was determined spectrophotometrically at 545 m ⁇ . Similarly, optical densities were recorded for a positive control (10 ml water and 0.2 ml blood) and a negative control (10 ml Sodium Chloride and 0.2 ml blood). The results are listed in Table 25.
  • test material is non-hemolytic under conditions of the test.
  • test material Materials prepared in accordance with Example 1 (test material) were tested for their ability to cause mutagenic response in bacterial tester stains with and without the presence of an enzomatic activation system. The results of the test are in Table 26.
  • test material Nine sample weights of material prepared in accordance with Example 1 (test material) were extracted in distilled water in the following ratios: 4,000 mg/20 ml, 500 mg/20 ml, 100 mg/20 ml, 50 mg/20 ml, 4 mg/20 ml, 3 mg/20 ml, 2 mg/20 ml, 1 mg/20 ml, 1 mg/40 ml. Each sample was extracted at 121° C. for one hour.
  • the cells were resuspended, centrifuged, and decanted twice again, then stored for 72 hours at 4° C. At the end of the incubation period, the tubes at 37° C. were washed in the same manner as the refrigerated tubes. All tubes were assayed for protein content using a phenol reagent and measuring the degree of color development with the aid of a spectrophotometer. The average Optical Density (O. D.) of each set of five replicate tubes was determined and the percent of inhibition of cell growth was calculated as follows: ##EQU1##
  • the precision of the assay is approximately ⁇ 10%. That is, the range of values expected for a non-toxic biomaterial in the nine point percent ICG assay would fall between ⁇ 10% inhibition. All nine extracts fall within this range and, therefore, do not produce inhibition of cell growth.
  • PMMA/PERMASORB MA co-polymer materials prepared in accordance with Example 1 were also tested for transmittance of radiation and were compared to: (1) a standard intraocular lens formed of PMMA; (2) a human lens (age 22 years); and (3) a human lens (age 53 years). The results are listed below in Table 28.
  • the UV absorbing lens material prepared in accordance with Example 1 has a capability to absorb ultraviolet radiation that is similar to the ultraviolet absorbing capability of a natural human lens.
  • a homopolymer of such a polymerizable chromophoric compound described above can also be formed, comminuted, and mixed with methyl methacrylate monomer, which is then polymerized to form the ultraviolet radiation absorbing lens of this invention.
  • the molecular weight of the homopolymer must be sufficiently high to inhibit leaching. Leaching can also be inhibited or prevented by addition of cross-linking agents such as ethylene glycol dimethacrylate to the methyl methacrylate monomer/homopolymer mixture.

Landscapes

  • Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Oral & Maxillofacial Surgery (AREA)
  • Chemical & Material Sciences (AREA)
  • Transplantation (AREA)
  • General Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Animal Behavior & Ethology (AREA)
  • Epidemiology (AREA)
  • Dermatology (AREA)
  • Medicinal Chemistry (AREA)
  • Ophthalmology & Optometry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Cardiology (AREA)
  • Engineering & Computer Science (AREA)
  • Biomedical Technology (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Vascular Medicine (AREA)
  • Materials For Medical Uses (AREA)

Abstract

An intraocular lens capable of absorbing ultraviolet radiation and, additionally, a method for forming the lens is provided. The intraocular lens comprises a polymer matrix that is biocompatible with body tissue and fluids and comprises polymethylmethacrylate and a chromophoric compound. The intraocular lens preferably has about the same capability for absorbing ultraviolet radiation as does the natural crystalline lens of the eye. In one embodiment, the intraocular lens is formed by co-polymerizing a polymerizable derivate of 2,4-dihydroxybenzophenone and methyl methacrylate monomer to form an ultraviolet light absorbing co-polymer additive. The co-polymer additive is mixed with methyl methacrylate monomer for forming a prepolymer solution that is then cured. The intraocular lens is formed from the solid cured co-polymer.

Description

CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of application Ser. No. 376,666 filed May 10, 1982, now abandoned, which is incorporated herein by this reference.
FIELD OF THE INVENTION
This invention relates to an intraocular lens capable of absorbing ultraviolet radiation and, additionally, to a method for forming the lens.
BACKGROUND OF THE INVENTION
The problem of restoring useful vision to a human eye after its cataractus natural lens has been removed has been with us since the introduction of cataract surgery. The solution to this problem has included the use of spectacle lenses, contact lenses, and permanent implantation into the eye of a man-made lens, i.e., an intraocular lens.
Since 1949, when the first implant of an intraocular lens was made, hundreds of thousands of persons have had such implants. Recent advances in cataract surgery have now made the intraocular lens implant procedure a safer and more popular alternative. For example, it is estimated that nearly 40 percent of the people now undergoing cataract surgery select a lens implant, i.e., an intraocular lens, instead of wearing contact lenses or thick cataract-type spectacles.
Although silicate glass was initially considered for use in intraocular lenses, generally such lenses are now made of polymethylmethacrylte (PMMA). PMMA is a polymer formed by polymerization of methyl methacrylate monomer (MMA monomer).
In the aphakic eye, the cornea and crystalline lens work together to absorb ultraviolet radiation or light. The cornea absorbs virtually all of the ultraviolet radiation below 300 nanometers (nm) that reaches the eye (almost all ultraviolet radiation below 286 nm is absorbed by the ozone layer in the earth's atmosphere). Although the cornea also absorbs a portion of the ultraviolet radiation between 300 nm and 400 nm, the natural crystalline lens absorbs the major portion of the ultraviolet radiation in this range.
Thus, when the natural crystalline lens is removed from the eye, ultraviolet radiation that would otherwise have been absorbed by the natural lens can reach the retina.
Recent evidence indicates that the retina can be damaged by ultraviolet radiation. For example, ultraviolet radiation is considered by many opthamologists as a casual factor in erythropsia ("pink vision"), cystoid macular edema, and macular degeneration.
It is thought that retinal damage by ultraviolet radiation results from absorption of light energy and conversion of this energy into heat within the cells. Damage to the retina can also result from molecular absorption of ultraviolet radiation which can place a cellular molecular species in an excited state, resulting in various chemical reactions of the excited species.
It appears that damage to the eye from ultraviolet radiation is cumulative. Thus, it is very important that an individual who has his natural crystalline lens removed take precautions to shield the retina of his eye from ultraviolet radiation.
Studies have also provided supporting evidence to show the ultraviolet radiation is a causal factor in polymer degradation of polymethylmethacrylate, the material from which intraocular lenses can be made. Thus, it is also important that an implanted intraocular lens be protected from ultraviolet radiation.
Since polymethylmethacrylate does not absorb any significant portion of the ultraviolet radiation in the 300-400 nm range, persons who have had a polymethylmethacrylate intraocular lens implant have been prone to retinal damage from ultraviolet radiation or have had to protect their pseudophakic eye by using spectacle lenses having ultraviolet light absorbing capability.
It is important, therefore, that an intraocular lens be provided that has ultraviolet absorbing capabilities, firstly to protect the retina of the eye from radiation damage, and secondly to retard damage to the intraocular lens itself from such ultraviolet radiation. It is desired that the ultraviolet absorbing intraocular lens have absorbing capabilities which approximate the capabilities of the natural crystalline lens which has been removed. Further, the ultraviolet absorbing intraocular lens may be biocompatible with body fluids and tissue and have desired optical properties.
SUMMARY OF THE INVENTION
This invention relates to an ultraviolet radiation absorbing introacular lens for implantation into a human eye. The intraocular lens comprises an ultraviolet radiation absorbing co-polymer physically trapped within a polymer matrix, such as polymethylmethacrylate for example. The ultraviolet absorbing co-polymer is formed by co-polymerizing a polymerizable derivative of dihydroxybenzophenone with a monomer suitable for making intraocular lenses, e.g., methyl methacrylate. The intraocular lens is biocompatible with body tissue and fluids and has about the same capability for absorbing ultraviolet radiation as does the natural crystalline lens of the eye.
In an exemplary embodiment, the ultraviolet radiation absorbing intraocular lens is formed by co-polymerizing a polymerizable derivative of 2,4-dihydroxybenzophenone and methyl methacrylate monomer to form an ultraviolet radiation absorbing co-polymer additive. The ultraviolet radiation absorbing co-polymer additive is mixed with methyl methacrylate monomer for forming a prepolymer solution. The prepolymer solution is cured to form the ultraviolet radiation absorbing intraocular lens.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other features, aspects, and advantages of the present invention will become more apparent when considered with respect to the following description, appended claims, and accompanying drawings, wherein:
FIG. 1 is a plan view of an exemplary intraocular lens assembly comprising a lens having an ultraviolet radiation absorbing capability provided in accordance with practice of this invention; and
FIG. 2 is a side view of the exemplary intraocular lens assembly of FIG. 1.
DETAILED DESCRIPTION
Referring to FIGS. 1 and 2, there is shown a plan view (FIG. 1) and a side view (FIG. 2) of an intraocular lens assembly 10 for implantation into the human eye provided in accordance with practice of principles of this invention. The intraocular lens assembly 10 comprises one or more non-optical "haptic" components 12 connected to an optical component or lens 14. The haptic components are useful for supporting or attaching the lens to an aphakic eye.
The lens 14 comprises an ultraviolet radiation absorbing co-polymer physically trapped within a polymer matrix for example, of polymethylmethacrylate. The ultraviolet radiation absorbing co-polymer is formed by co-polymerizing a polymerizable chromophoric compound for example, a polymerizable derivative of dihydroxybenzophenone, with a monomer suitable for making such lenses, for example, with methyl methacrylate. The resulting intraocular lens preferably has about the same capability for absorbing ultraviolet radiation as does the natural crystalline lens of the eye and is biocompatible with body tissue and fluids.
Although the lens 14 of the assembly 10 is a "planoconvex lens", i.e., it has a convex surface 16 on one side and a flat or planar surface 18 on its other side, lenses having any desired design configuration can be provided. Further, although two haptics 12 are shown, fewer or more haptics can be used as desired and the haptics can have configurations other than the configuration of the haptics shown in the exemplary embodiment.
The lens 14 preferably is formed in a series of steps which include co-polymerizing the selected polymerizable chromophoric compound with methyl methacrylate monomer to form an ultraviolet radiation absorbing co-polymer additive; dissolving the ultraviolet radiation absorbing co-polymer additive in methyl methacrylate monomer to form a prepolymer solution; curing the prepolymer solution; and finishing the lens as necessary from the cured prepolymer.
Exemplary chromophoric compounds useful in practice of this invention are ethylenically unsaturated derivatives of dihydroxybenzophenone selected from the group consisting of: ##STR1## wherein X is an ethylenically unsaturated radical selected from the group consisting of acryloxy beta-hydroxypropyl and methacryloxy beta-hydroxypropyl radicals and wherein R represents a radical selected from the class consisting of hydrogen and hydroxy radicals.
As representative of dihydroxybenzophenone derivatives useful in practice of this invention, there may include derivatives of 2,4-dihydroxybenzophenone such as 4-acryloxy beta-hydroxypropyl ether of 2,4-dihydroxybenzophenone; the 4-methacryloxy beta-hydroxypropyl ether of 2,4-dihydroxybenzophenone, i.e., 2-hydroxy-4-(2-hydroxy-3-methacrylyloxy)propoxybenzophenone; the 4-acryloxy beta-hydroxypropyl ether of 2,2',4-trihydroxybenzophenone; the 4-methacryloxy beta-hydroxypropyl ether of 2,2',4-trihydroxybenzophenone; the 4,4'-di(acryloxy beta-hydroxypropyl) ether of 2,2',4,4'-tetrahydroxybenzophenone; and the 4,4'-di(methacryloxy beta-hydroxypropyl) ether of 2,2',4,4'-tetrahydroxybenzophenone. Thus, mono- and difunctional ethylenically unsaturated derivatives of dihydroxybenzophenone are useful in practice of the invention.
Other chromophoric compounds may also be used such as allylic substituted benzophenones, i.e., 2-hydroxy-3-allyl-4,4' dimethoxybenzophenone, ethylenically or allylically substituted phenyl benzotriazoles, provided that they are capable of readily undergoing vinyl-type polymerization reactions and thus can form a co-polymer with methyl methacrylate monomer.
Preferably, the chromophoric compound is a material sold by National Starch and Chemical Corporation, Resin Division, Bridgewater, N.J., under the trademark PERMASORB MA. PERMASORB MA is represented by National Starch to include 2-hydroxy-4-(2-hydroxy-3-methacrylyloxy)propoxybenzophenone, which has the following chemical structure: ##STR2##
Additional information relating to chromophoric compounds useful in practice of this invention can be found in U.S. Pat. No. 3,162,676 issued on Dec. 22, 1964, to Goldberg et al. U.S. Pat. No. 3,162,676 is incorporated herein by this reference.
In a presently preferred process for forming an ultraviolet radiation absorbing lens, methyl methacrylate monomer and PERMASORB MA are dissolved in dry ethyl acetate to form a "monomer mix". An "initiator mix" is prepared by dissolving an initiator in dry ethyl acetate. Presently preferred initiators are benzoyl peroxide, tert-butyl hydro peroxide, cumene hydro peroxide, 2-azobisisobutyronitrile, and azoisobutylnitrile (AIBN) and the like.
The monomer mix and initiator mix are mixed together in a reaction flask and heated to reflux at about 77° C.±3° C. for a period of time to form the co-polymer of methyl methacrylate and PERMASORB MA co-polymer). The reaction mixture is then cooled and added to 5 to 6 times its volume of anhydrous methanol which causes the ultraviolet radiation absorbing PMMA/PERMASORB MA co-polynmer to precipitate as a solid polymer mass. The ultraviolet radiation absorbing solid polymer mass is comminuted, i.e., ground into a fine powder, and dried. The comminuted co-polymer is purified by "Soxhlet" extraction to remove remaining unreacted raw materials and solvents. The solid co-polymer is then vacuum dried and comminuted. The comminuted co-polymer (the ultraviolet radiation absorbing PMMA/PERMASORB MA co-polymer additive) is dissolved in methyl methacrylate monomer to form a prepolymer solution and the prepolymer solution is cured to form the ultraviolet radiation absorbing intraocular lens of this invention wherein the PMMA/PERMASORB MA co-polymer is trapped within the polymethylmethacrylate matrix of the lens.
Standard methods known in the art for curing prepolymers can be used to form the intraocular lens of this invention. For example, the prepolymer solution can be poured into a mold having a desired optical configuration. The mold, after it is filled, is then placed into an autoclave and subjected to elevated temperature and pressure conditions for curing the lens. After completion of the desired time-temperature/pressure cycle in the autoclave, the mold is removed therefrom and the lens blank is removed from the mold. The edges are then removed from the lens blank by machining and haptics are connected to the lens in appropriate holes formed in its edges. After the haptics are attached, the finished intraocular lens is inspected, sterilized, and packaged for shipment.
Preferably, the ratio of the weight of the chromophoric compound to the total weight of chromophoric compound plus methyl methacrylate monomer in the monomer mix is small enough so that the co-polymer formed, i.e., the co-polymer additive, is soluble in polymethylmethacrylate. This is important so that the finished intraocular lens has a desired optical clarity. For example, it is preferred that the ratio of the weight of PERMASORB MA to the total weight of PERMASORB MA plus methyl methacrylate monomer in the monomer mix is such that, upon polymerization of the monomer mix, less than about 15 percent by weight of the PMMA/PERMASORB MA co-polymer additive formed comprises PERMASORB MA. It is important that the PMMA/PERMASORB MA co-polymer comprises less than about 15% by weight PERMASORB MA because it has been found that when such a co-polymer additive comprises a higher weight percentage of PERMASORB MA, the co-polymer is not soluble at any proportion in polymethylmethacrylate. Thus, lenses formed using PMMA/PERMASORB MA co-polymer additive comprising more than about 15% by weight PERMASORB MA tend to be cloudy or hazy. For example, lenses formed using PMMA/PERMASORB MA co-polymer additives comprising 16.1 %, 22.5%, and 50% by weight PERMASORB MA all produced hazy lenses, while lenses formed of PMMA/PERMASORB MA co-polymer additive comprising 5.7%, 10%, and 12% were clear. Surprisingly, this appears to be the case regardless of the weight ratio of PMMA/PERMASORB MA co-polymer additive to MMA monomer used to form the PMMA/PERMASORB MA intraocular lens.
Preferably, the finished lens comprises from about four percent to about five percent by weight PERMASORB MA.
It has been found that when PERMASORB MA and methyl methacrylate monomer are co-polymerized under reaction conditions such as those described in detail below, only about 50 to 60 percent by weight of the PERMASORB MA in the monomer mixture is incorporated into the co-polymer additive formed. This must be taken into account when selecting the desired ratio of the weight of PERMASORB MA to the weight of methyl methacrylate monomer used for forming the monomer mixture to provide a co-polymer additive having a desired, selected weight percent of PERMASORB MA.
The following non-limiting example of a presently preferred process for forming an ultraviolet radiation absorbing intraocular lens material comprising an ultraviolet absorbing co-polymer, consisting essentially of methyl methacrylate monomer co-polymerized with PERMASORB MA, physically trapped within a polymethylmethacrylate polymer matrix is presented to further demonstrate practice of principles of this invention.
EXAMPLE 1 PREPARATION OF AN ULTRAVIOLET RADIATION ABSORBING INTRAOCULAR LENS MATERIAL
80 grams of methyl methacrylate monomer supplied by Rohm & Haas Company and 20 grams of PERMASORB MA were dissolved at room temperature in 20 grams of dry ethyl acetate to form a monomer mix.
Separately, an initiator mix was prepared by dissolving 1 gram of azoisobutylnitrile (AIBN) at room temperature in 25 grams of dry ethyl acetate.
20 grams of the monomer mix, 30 grams of ethyl acetate, and 0.5 grams of AIBN were charged into a reaction flask equipped with a stirring motor and heating mantle. The charge in the reaction flask was brought to reflux (77° C.) and held at reflux for 15 minutes. Nitrogen was bubbled through the charge in the reaction flask during the reaction and it was constantly stirred.
After the 15-minute time period, dropwise additions of the balance of the monomer mix (100 grams) and initiator mix (26 grams) were started simultaneously into the refluxing materials in the reaction flask. (Stirring and nitrogen bubbling was continued during the entire reaction.) The monomer mix was added over a period of about 21/2 hours, while the initiator mix was added over a period of about 31/2 hours. Following the completion of the monomer mix addition, 30 grams of dry ethyl acetate were added in dropwise fashion to the reaction flask over a period of 30 minutes.
Following the completion of all additions, reflux was continued for 11/2 hours. At the end of the 11/2 hour period, 60 grams of ethyl acetate were added and the reaction mixture was cooled to room temperature. Methanol, at about 5 to 6 times the volume of the cooled reaction mixture, was then added slowly (about 5 to 10 minutes) to the reaction mixture (while stirring) to precipitate PMMA/PERMASORB MA co-polymer that had formed. The resultant wet PMMA/PERMASORB MA co-polymer blob was placed in a blender with 200 ml of methanol at room temperature to form a fine suspension of the co-polymer. The co-polymer was then filtered and extracted in methanol with a Soxhlet extractor using a cellulose thimble. After methanol extraction, the co-polymer blob was placed in a blender with methanol and again a fine suspension of the co-polymer was formed. The suspension was filtered and, to remove any cellulose fibers from the co-polymer, the filtered co-polymer blob was placed in methylene chloride (CH2 Cl2) and dissolved. The methylene chloride/co-polymer solution was then filtered and the co-polymer was reprecipitated from the filtered solution in methanol. The co-polymer (the PMMA/PERMASORB MA co-polymer additive) was then dried and ground into a fine powder.
To form the prepolymer solution, about 30 percent by weight of the co-polymer powder (the PMMA/PERMASORB MA co-polymer additive) was placed into a reaction flask with about 70 percent by weight methyl methacrylate monomer. The monomer/co-polymer mixture was stirred for about 14 hours at room temperature to dissolve the powder. Benzoyl peroxide initiator was added (0.05% by weight based on the weight of methyl methacrylate monomer) and mixed into the prepolymer solution for about 30 minutes at room temperature. The prepolymer solution was then subjected to a vacuum process to remove any dissolved gases and air bubbles.
The degassed prepolymer solution was filtered through a 5 micron filter as it was being poured into a mold for curing. The mold was then placed into a casting chamber and subjected to conditions of temperature, pressure, and time for polymerizing or curing the prepolymer solution to form a solid polymeric ultraviolet radiation absorbing material comprising the ultraviolet radiation absorbing co-polymer additive physically trapped within a polymethylmethacrylate polymer matrix.
An intraocular lens provided in accordance with this invention is finished from the ultraviolet radiation absorbing polymeric material by machining and other appropriate lens finishing operations.
It is necessary that a device that is to be implanted in the body, such as an intraocular lens provided in accordance with practice of principles of this invention, is biocompatible with body tissue and fluids, i.e., it does not produce adverse local or systemic responses or cause sensitization leading to an allergic response when implanted. To determine biocompatibility of ultraviolet absorbing materials prepared in accordance with Example 1, such materials were tested first to determine whether raw materials used in their preparation tend to leach from them, thereby possibly inhibiting biocompatibility. Further testing of the ultraviolet radiation absorbing materials prepared in accordance with Example 1 is, however, required by the Food and Drug Administration (FDA) to insure that they are biocompatible with body tissues and fluids and can be used in devices that are to be implanted in the human body. Therefore, such materials were tested directly for biocompatibility by various accepted biological tests.
The details of the tests and the results are set forth in Examples 2 to 20 below.
EXAMPLE 2 MMA MONOMER LEACHING BY MEASUREMENT OF RESIDUAL MONOMER IN MATERIALS PREPARED IN ACCORDANCE WITH EXAMPLE 1
The amount of MMA monomer that leaches from materials prepared in accordance with Example 1 (test material) was determined by measuring the amount of MMA monomer in such a material before and after a 24-hour saline extraction.
Three cast sheets of test material were subjected to ethylene oxide sterilization. The three sample sheets were then divided into two parts each and labeled as follows: UVI-EXPOSED, UVI-UNEXPOSED, UVII-EXPOSED, UVII-UNEXPOSED, UVIII-EXPOSED, and UVIII-UNEXPOSED.
All samples labeled as UV exposed were then exposed for 235 hours to UV radiation using an SP-5000 HG-XE UV Exposure System manufactured by Optical Radiation Corporation, assignee of this application. This is equivalent to 14.5 years of normal UV radiation exposure.
Each of the six labeled sample parts were then divided into smaller pieces (for subsequent sampling). A representative piece of each sample part was removed for % MMA residual monomer analysis. % MMA monomer was measured by dissolving the entire piece of material in acetone and performing a gas chromatograph (GC) analysis for MMA monomer content. The method used to perform the GC analysis was similar to Galin, M. A. et al; Methyl Methacrylate Monomer in Intraocular Lenses of PMMA; Arch. Opthalmol, Vol. 98, January 1980, pp 120-121. All other sample pieces were placed into separate glass containers filled with USP saline solution for extraction at 37±4° C. After 24 hours of extraction, a test material sample was removed from each container and analyzed for % MMA residual monomer. Again, % MMA monomer was measured by dissolving the entire piece of test material in acetone and performing GC analysis for MMA content. The results are listed in Table 1.
              TABLE 1
______________________________________
Results
% MMA Residual Monomer
Sample            0 Hours  24 Hours
______________________________________
UVI-UNEXPOSED     0.61     0.55
UVI-EXPOSED       0.56     0.57
UVII-UNEXPOSED    0.62     0.53
UVII-EXPOSED      0.53     0.49
UVIII-UNEXPOSED   0.53     0.58
UVIII-EXPOSED     0.56     0.53
______________________________________
The results for both irradiation exposed and non-exposed test materials indicate that MMA monomer does not leach from such materials.
EXAMPLE 3 MMA MONOMER LEACHING BY MEASUREMENT OF MONOMER IN EXTRACT
The amount of MMA monomer that leaches from materials prepared in accordance with Example 1 (test material) was determined by measuring the amount of MMA monomer in saline extract during a 21-day saline extraction.
Three cast sheets of test material were subjected to ethylene oxide sterilization. The three sample sheets of test material were then divided into two parts each and labeled as follows: UVIA-EXPOSED, UVIA-UNEXPOSED, UVIIA-EXPOSED, UVIIA-UNEXPOSED, UVIIIA-EXPOSED, and UVIIIA-UNEXPOSED.
All test material samples labeled as UV exposed were than exposed for 127 hours to UV radiation using an SP-5000 HG-XE UV Exposure System manufactured by Optical Radiation Corporation. This is equivalent to 7.8 years of normal exposure.
Each of the six labeled test material sample parts were then divided into smaller pieces for subsequent sampling. A representative piece of each sample part was removed for % MMA residual monomer analysis. % MMA monomer was measured by dissolving the entire piece of test material in acetone and performing GC analysis for MMA monomer content. All other sample pieces of test material were placed into separate glass containers filled with USP saline solution for extraction at 37±4° C. (similar to the environment within the natural eye). Representative extract samples were removed at various time periods throughout the 21-day extraction, i.e., days 4 through 7, days 12 and 13, and days 19 and 20, and subjected to GC analysis for determination of % extracted MMA monomer. The ratio of aqueous to acrylic was 30 to 1.
Tables 2 through 8 contain the results of these studies.
              TABLE 2
______________________________________
% RESIDUAL MMA MONOMER LEVELS IN TEST
MATERIAL SAMPLES PRIOR TO LEACHING
Sample Identification
                 % MMA Monomer
______________________________________
UVIA EXPOSED     .46%
UVIA UNEXPOSED   .42%
UVIIA EXPOSED    .45%
UVIIA UNEXPOSED  .47%
UVIIIA EXPOSED   .43%
UVIIIA UNEXPOSED .43%
______________________________________

              TABLE 3
______________________________________
RESIDUAL MMA MONOMER IN EXTRACT AND % UV
TRANSMISSION OF TEST MATERIAL SAMPLE
AND EXTRACT
TEST SAMPLE IDENTIFICATION: UVIA-EXPOSED
      % UV
      Trans-            % UV    % UV
      mission  Thick-   Trans-  Trans-  % MMA
      of Test  ness     mission mission Residual
      Material of Test  Normalized
                                of Extract
                                        in
Day   at 390 nm
               Material to .705 mm
                                at 350 nm
                                        Extract**
______________________________________
 0    6.0      .68      5.4      88.7*
 5    6.2      .679     5.6     90.0    ND
 6    5.6      .679     5.0     88.0    ND
12    5.3      .729     5.8     87.0    ND
13    5.1      .728     5.6     89.0    ND
19    5.7      .705     5.7     89.3    ND
20    5.0      .705     5.0     88.8    ND
______________________________________
 *88.7% is the UV transmission of saline solution at 350 nm.
 **Detection Limit: 60 ppm MMA monomer to aqueous.

              TABLE 4
______________________________________
RESIDUAL MMA MONOMER IN EXTRACT AND % UV
TRANSMISSION OF TEST MATERIAL SAMPLE
AND EXTRACT
TEST SAMPLE IDENTIFICATION: UVIA-UNEXPOSED
      % UV
      Trans-            % UV    % UV
      mission  Thick-   Trans-  Trans-  % MMA
      of Test  ness     mission mission Residual
      Material of Test  Normalized
                                of Extract
                                        in
Day   at 390 nm
               Material to .705 mm
                                at 350 nm
                                        Extract**
______________________________________
0     6.8      .670     5.9      88.7*
6     6.8      .670     5.9     85.2    ND
7     6.5      .680     5.9     83.5    ND
13    6.7      .669     5.8     88.8    ND
______________________________________
 *88.7% is the UV transmission of saline solution at 350 nm.
 **Detection Limit: 60 ppm MMA monomer to aqueous.

              TABLE 5
______________________________________
RESIDUAL MMA MONOMER IN EXTRACT AND % UV
TRANSMISSION OF TEST MATERIAL SAMPLE
AND EXTRACT
TEST SAMPLE IDENTIFICATION: UVIIA-EXPOSED
      % UV
      Trans-            % UV    % UV
      mission  Thick-   Trans-  Trans-  % MMA
      of Test  ness     mission mission Residual
      Material of Test  Normalized
                                of Extract
                                        in
Day   at 390 nm
               Material to .705 mm
                                at 350 nm
                                        Extract**
______________________________________
0     5.7      .68      5.1      88.7*
4     5.3      .718     5.6     88.8    ND
5     4.8      .722     5.2     90.0    ND
6     5.1      .722     5.5     88.7    ND
18    6.0      .695     5.7     89.7    ND
20    5.7      .695     5.5     90.2    ND
______________________________________
 *88.7% is the UV transmission of saline solution at 350 nm.
 **Detection Limit: 60 ppm MMA monomer to aqueous.

              TABLE 6
______________________________________
RESIDUAL MMA MONOMER IN EXTRACT AND % UV
TRANSMISSION OF TEST MATERIAL SAMPLE
AND EXTRACT
TEST SAMPLE IDENTIFICATION: UVIIA-UNEXPOSED
      % UV
      Trans-            % UV    % UV
      mission  Thick-   Trans-  Trans-  % MMA
      of Test  ness     mission mission Residual
      Material of Test  Normalized
                                of Extract
                                        in
Day   at 390 nm
               Material to .705 mm
                                at 350 nm
                                        Extract**
______________________________________
 0    5.7      .68      5.1      88.7*
12    6.4      .680     5.8     88.3    ND
13    5.6      .682     5.1     88.5    ND
19    5.8      .678     5.2     89.4    ND
20    6.4      .677     5.7     88.5    ND
______________________________________
 *88.7% is the UV transmission of saline solution at 350 nm.
 **Detection Limit: 60 ppm MMA monomer to aqueous.

              TABLE 7
______________________________________
RESIDUAL MMA MONOMER IN EXTRACT AND % UV
TRANSMISSION OF TEST MATERIAL SAMPLE
AND EXTRACT
TEST SAMPLE IDENTIFICATION: UVIIIA-EXPOSED
      % UV
      Trans-            % UV    % UV
      mission  Thick-   Trans-  Trans-  % MMA
      of Test  ness     mission mission Residual
      Material of Test  Normalized
                                of Extract
                                        in
Day   at 390 nm
               Material to .705 mm
                                at 350 nm
                                        Extract**
______________________________________
 0    6.4      .65      5.1      88.7*
 4    4.0      .750     4.8     88.5    ND
 5    4.0      .745     4.8     90.0    ND
12    5.0      .740     5.8     87.7    ND
13    5.0      .739     5.7     89.5    ND
18    5.5      .710     5.6     89.7    ND
20    5.3      .710     5.4     89.7    ND
______________________________________
 *88.7% is the UV transmission of saline solution at 350 nm.
 **Detection Limit: 60 ppm MMA monomer to aqueous.

              TABLE 8
______________________________________
RESIDUAL MMA MONOMER IN EXTRACT AND % UV
TRANSMISSION OF TEST MATERIAL SAMPLE
AND EXTRACT
TEST SAMPLE IDENTIFICATION: UVIIIA-UNEXPOSED
      % UV
      Trans-            % UV    % UV
      mission  Thick-   Trans-  Trans-  % MMA
      of Test  ness     mission mission Residual
      Material of Test  Normalized
                                of Extract
                                        in
Day   at 390 nm
               Material to .705 mm
                                at 350 nm
                                        Extract**
______________________________________
 6    5.0      .718     5.3      89.0*
12    4.9      .715     5.1     89.0    ND
14    4.9      .714     5.1     89.0    ND
19    5.5      .713     5.7     88.4    ND
20    4.9      .715     5.1     88.5    ND
______________________________________
 *88.7% is the UV transmission of saline solution at 350 nm.
 **Detection Limit: 60 ppm MMA monomer to aqueous.
As shown in Table 2, residual MMA monomer at time zero was significantly low for all test material samples. In addition, as shown in Tables 3-8, residual MMA monomer could not be detected in any of the extract samples. Thus, the results of the tests of Examples 2 and 3 indicate that MMA monomer leaching from materials prepared in accordance with Example 1 is not a problem.
EXAMPLE 4 PERMASORB MA LEACHING DETERMINED BY SPECTRAPHOTOMETRIC MEASUREMENTS OF UV TRANSMISSION OF EXTRACTS
The amount of PERMASORB MA that leaches from materials prepared in accordance with Example 1 (test material) was determined by subjecting such test materials to 20 days saline extraction and then measuring the before and after UV transmission of the extract.
The test of this Example was run in conjunction with Example 3 described above. However, subsequent to the initiation of the extraction time period, the following procedure was followed: Representative sample test material pieces and extract samples from each glass container were removed at various time periods throughout the 21-day extraction, i.e., days 4 through 7, days 12 and 13, and days 19 and 20. For each test material sample removed, its thickness and % UV transmission were measured. For each extract sample removed, a measurement of the % UV transmission was performed. The UV spectrophotometer is repeatable to ±1% providing a method that can reliably quantify 2.2 ppm PERMASORB MA. The sensitivity of the instrument is 0.7 ppm.
To further support this analysis, additional samples of the extract solutions were removed on various days throughout the 21-day extraction period and submitted to an independent testing laboratory for High Performance Liquid Chromatography (HPLC) analysis. Utilizing HPLC, the extract solution is subjected to a more severe detection method which can reliably quantify 0.1 ppm PERMASORB MA in the presence of 0.5% monomer and the presence of 0.5 ppm benzoic acid.
Tables 3 through 8 contain the results of these studies (excluding the results of the HPLC determination). In general, if the PERMASORB MA was being extracted, increased absorption of the saline extract solutions would be anticipated. At the same time, increased transmission of the test material samples would be anticipated. Upon review of this data, neither of these two observations occurred with any significance. In fact, after correction for thickness variation of material samples (i.e., normalizing each sample), the difference in % UV transmission can be attributed to the accuracy (±1%) of the UV spectrophotometer. There was no significant difference in the UV transmission spectra of the saline solution extract samples. This was the case both for the test materials that were not exposed to UV radiation and also for the materials that were exposed.
Additionally, the HPLC analysis of the extracts from leached test materials (both irradiation exposed and non-exposed) showed no detectable UV absorber after a total of 19 days leaching at 37±4° C.
EXAMPLE 5 DETERMINATION OF THE AMOUNT OF UNREACTED PERMASORB MA IN MATERIALS PREPARED IN ACCORDANCE WITH EXAMPLE 1
Eight (8) samples of cast material prepared in accordance with Example 1 (test material) were used. Four of the eight (8) samples of test material were sterilized by ethylene oxide sterilization.
All test material samples were placed in a 10 ml vial and then dissolved in HPLC grade acetone for 24 hours at room temperature. All sample vials were sealed with a teflon septum. (Note: To accelerate solution, some samples were subjected to ultrasonification at 65° C. This was sometimes necessary due to the degree of cross-linking.)
The resultant samples were then subjected to HPLC for unreacted PERMASORB MA. The detection limit for this test was 7 ppm. The results of this test are listed in Table 9.
              TABLE 9
______________________________________
Test Sample   PERMASORB MA (ppm)
______________________________________
1. (sterilized)
              7
2. (non-sterilized)
              ND
3. (non-sterilized)
              ND
4. (sterilized)
              ND
5. (non-sterilized)
              7
6. (non-sterilized)
              ND
7. (sterilized)
              8
8. (sterilized)
              9
______________________________________
Under worst case conditions, i.e., completely dissolving the test material sample in organic solvent and utilizing HPLC (possibly the most severe and sensitive test for UV absorber detection), the highest level of unreacted PERMASORB MA found was 9 ppm. This data, along with previous leachability data using isotonic saline solution as an extracting medium, indicates that leachability of PERMASORB MA is not a problem. This is the case for materials that are not subjected to ethylene oxide sterilization, as well as for materials that are ethylene oxide sterilized.
EXAMPLE 6 DETERMINATION OF RESIDUAL AZOISOBUTYLNITRILE IN MATERIALS PREPARED IN ACCORDANCE WITH EXAMPLE 1
Three samples of materials prepared in accordance with Example 1 were tested for azoisobutylnitrile utilizing wet chemistry techniques (ARLI Method 600-104). The results of the tests are listed in Table 10.
              TABLE 10
______________________________________
Sample          AIBN, g/100 ml
______________________________________
XP-30-81-0041/0032
                <0.008
XP-30-81-0041/0045
                <0.008
XP-30-81-0041/0047
                <0.008
______________________________________
The conclusion was that no AIBN was in any of the samples. Thus, AIBN leachability from materials prepared in accordance with Example 1 is not a problem.
EXAMPLE 7 PHOTODEGRADATION OF MATERIALS PREPARED IN ACCORDANCE WITH EXAMPLE 1
To determine if photodegradation of material prepared in accordance with Example 1 (test material) could occur, such materials were subjected to high dosage ultraviolet radiation. The materials were subjected to two levels of exposure; the first level was equivalent to 7.8 years of normal eye exposure to UV radiation and the second level was equivalent to 14.5 years. The UV radiation exposed samples were evaluated for any increase in residual MMA monomer, changes in their UV transmission characteristics, and the extent, if any, of changes in PERMASORB MA and MMA leachability rates compared to non-UV exposed control material.
The results of the 7.8 year and 14.5 year ultraviolet exposure tests showed no changes between the before and after exposed test material samples. The residual monomer in the samples both before and after exposure were the same; the ultraviolet transmission of the material before and after exposure to high dosages of UV radiation remained unchanged; and there was no difference in the monomer leachability, i.e., none detected, on the before and after exposure samples. The same results were found with regard to the PERMASORB MA leachability of the samples, i.e., none detected.
In addition to the analytical tests set forth in Examples 2-7, which indicated that leaching is not a problem, various in-vivo and in-vitro biological tests were conducted by an independent testing laboratory on materials prepared in accordance with Example 1 to confirm that such materials are biologically compatible with body tissue and fluids.
EXAMPLE 8 ACUTE SYSTEMIC TOCICITY-T 12/4 (CURRENT USP)
Healthy, young, white mice ranging in body weight from 17 to 23 grams were injected either intraveneously or intraperitoneally with one of four different extracts (saline, alcohol/saline, polyethylene glycol 400, and cottonseed oil) of a material prepared in accordance with Example 1. The extracts were prepared at 121° C. for one hour. Two groups, each consisting of five mice, were used for each extract. One group was injected with the extract of the test material, while the other group was injected with a blank. After injection, the animals were observed immediately and at 4, 24, 48, and 72 hours. Initial and final body weights were recorded, as well as mortalities and/or reactions. If, during the observation period, none of the animals treated with the extract of the test material show a significantly greater reaction than the animals treated with the blank, the material meets the requirements of the test. The results of the tests are recorded in Table 11.
                                  TABLE 11
__________________________________________________________________________
            Mortality and Body Weight Data
            TEST MATERIAL     BLANK
Extract Dose
            Animal
                 Weight (gms)
                         # Dead/
                              Animal
                                   Weight (gms)
                                           # Dead/
and Route   Number
                 Day 0
                     Day 3
                         # Tested
                              Number
                                   Day 0
                                       Day 2
                                           # Tested
__________________________________________________________________________
Sodium Chloride
            1    22  23  0/5  1    21  21  0/5
Injection   2    20  23       2    21  25
(I.V.: 50 ml/Kg)
            3    22  22       3    22  24
            4    21  22       4    22  25
            5    19  23       5    20  24
Ethanol in Sodium
            1    19  21  0/5  1    19  23  0/5
Chloride Injection (1:20)
            2    17  21       2    19  23
(I.V.: 50 ml/Kg)
            3    19  23       3    22  24
            4    18  21       4    19  23
            5    19  21       5    19  21
Polyethylene Glycol 400
            1    19  20  0/5  1    18  21  0/5
(I.P.: 10 g/Kg)
            2    18  21       2    19  23
            3    21  25       3    20  24
            4    21  25       4    20  25
            5    19  21       5    19  22
Cottonseed Oil
            1    19  25  0/5  1    18  23  0/5
(I.P.: 50 ml/Kg)
            2    21  26       2    18  22
            3    22  25       3    21  25
            4    20  22       4    19  22
            5    19  21       5    21  26
__________________________________________________________________________
The results indicated that there was no significant evidence of acute toxicity with the eluates.
EXAMPLE 9 INTRACUTANEOUS TOXICITY-T 13/4 (CURRENT USP)
Rabbits received a series of intracutaneous injections with up to four extracts (saline, alcohol/saline, polyethylene glycol 400, and cottonseed oil) of materials prepared in accordance with Example 1. The extracts were prepared at 121° C. for 1 hour. Two healthy, previously unused New Zealand white rabbits were used as test animals for each extract. Animals were housed individually and allowed food and water ad libitum. Prior to injection, the hair was closely clipped from the back and flanks of each rabbit. Exactly 0.2 ml of the extract of the test material was injected intracutaneously into ten separate sites on the right side of the back of each animal, while 0.2 ml of the extracting medium (blank) was injected into five separate sites on the left side. Injection sites were examined 24, 48, and 72 hours after injection for erythema and edema. The average tissue reaction to the extract of the test material was compared with the blank. The requirements of the test were met if no significant differences were noted. The results of the tests are recorded in Table 12.
              TABLE 12
______________________________________
          Rab-
          bit  24 HR.    48 HR.    72 HR.
Extract         No.    ER   ED   ER   ED   ER   ED
______________________________________
Sodium  Test    7057   0    0    0    0    0    0
Chloride
        Blank          0    0    0    0    0    0
(SC)    Test    7058   0    0    0    0    0    0
        Blank          0    0    0    0    0    0
Alcohol in
        Test    7059   0    0    0    0    0    0
Sodium  Blank          0    0    0    0    0    0
Chloride
        Test    7060   0    0    0    0    0    0
1:20    Blank          0    0    0    0    0    0
(AS)
Poly-   Test    7061   0    0    0    0    0    0
ethylene
        Blank          0    0    0    0    0    0
Glycol  Test    7062   0    0    0    0    0    0
400     Blank          0    0    0    0    0    0
(PEG)
Cottonseed
        Test    7063   3    3    3    3    2    2
Oil     Blank          3    3    3    3    2    2
(CSO)   Test    7064   3    2    2    2    1    1
        Blank          3    2    2    2    1    1
______________________________________
.sup.--X Test -  .sup.--X Blank =
               Δ    Pass   Fail
______________________________________
SC 0 - 0 =     0          X
AS 0 - 0 =     0          X
PEG 0 - 0 =    0          X
CSO 2.3 - 2.3 =
               0          X
______________________________________
 Key
 ER = Erythema
 0 = None
 1 = Barely Perceptible
 2 = Well Defined
 3 = Moderate
 4 = Severe
 ED = Edema
 0 = None
 1 = Barely Perceptible
 2 = Well Defined
 3 = Raised 1 mm
 4 = Raised >1 mm
The results indicated that there was no significant tissue reaction.
EXAMPLE 10 IMPLANTATION TEST-T 14/7 (CURRENT USP)
Two rabbits were implanted with four or more strips (10×1×1 mm) of material prepared in accordance with Example 1 (test material) via needle puncture into the paravertebral muscles. The tissue reaction was evaluated macroscopically after 7 days implantation and compared to a USP control plastic similarly implanted in the same rabbits. The results of the macroscopic evaluation are listed in Table 13.
              TABLE 13
______________________________________
Results of Macroscopic Examination:
______________________________________
Scoring
Rabbit   Sample        Test   Control
______________________________________
6773     1             1      0
         2             1      0
         3             0      0
         4             0      0
         5             0      0
6789     1             0      0
         2             0      0
         3             0      0
         4             0      0
         5             0      0
         Mean (.sup.--X)
                       0.2    0.0
______________________________________
Scoring Key
Score            Capsule Formation
______________________________________
0                None Noted
1                Up to 0.5 mm
2                0.5 to 1.0 mm
3                1.0 to 2.0 mm
4                >2.0 mm
______________________________________
Reaction Index
X (Test) - X (Control) = 0.2
______________________________________
  0-0.5            Not Significant
0.6-1.0            Trace
1.1-2.0            Slight
2.1-3.0            Moderate
>3.1               Marked
______________________________________
The results show that there was no significant tissue reaction with the test material as compared to the negative control material.
A microscopic evaluation of the implanted tissue was also conducted 7 days after implantation following routine staining of the tissues with Hematoxylin and Eosin. Tissue reactions were recorded for inflammation, chronic irritation, foreign body response, tissue scarring, and necrosis. The results of the microscopic evaluation are listed in Table 14.
                                  TABLE 14
__________________________________________________________________________
            Animal No:
            TEST      CONTROL       DIFFERENCE
OBSERVATION (0-4)
            6773
               6789   6773
                         6789       (Test # - Control)
__________________________________________________________________________
Inflammation
Polymorphonuclear
            0  0      0  0
Lymphocytes 1  1      1  1
Plasma Cells
            0  0      0  0
Macrophages 1  1      1  1
Giant Cells 0  0      0  0
Sub Total (× 2)
                   8            8 = 0
Fibroplasia 2  2      2  2
Fibrosis    1  1      1  1
Fatty infiltrate
            0  0      0  0
Necrosis    0  0      0  0
Sub Total          6            6 = 0
TOTAL          TEST:
                   14    CONTROL:
                                14 =
                                    0
Foreign Debris
            0  0      0  0
Number Sites Examined
            4  4      2  2
Results:
__________________________________________________________________________
 Score Guide (TestControl): 0 = Non irritant. 1-15 = Slight, 16-30 =
 Moderate. >30 = Severe for a two rabbit test.
The conclusion, based on the results of both the macroscopic and microscopic tests, is that test material prepared in accordance with Example 1 is a non-irritant.
EXAMPLE 11 OCULAR IRRITATION
Extracts of material prepared in accordance with Example 1 (test material) were injected into the anterior chamber of the eyes of a number of rabbits to determine the irritation or toxicity potential of the extracts.
Three vials of extract of test material exposed to UV radiation were provided and three vials of extract of test material that was not exposed to UV radiation were also provided. Two rabbits were treated from each vial.
Two vials of USP sodium chloride solution (0.9%) were provided as a control solution.
Fifteen healthy rabbits of the New Zealand white variety were selected from the stock colony. (Rabbits weighed 2.4-3.2 kg at initiation). The day before treatment, rabbits were examined by an ophthalmologist with the aid of a slit lamp biomicroscope. Rabbits showing significant abnormalities were replaced. Treatment groups were as follows:
______________________________________
        No.
Group   Rabbits    Right Eye    Left Eye
______________________________________
I       6          0.2 ml extract;
                                0.2 ml control
                   UV exposed   solution
II      6          0.2 ml extract;
                                0.2 ml control
                   not exposed  solution
III     3          No treatment No treatment
______________________________________
Rabbits were anesthetized by intramuscular injection of Acepromazine/Ketamine HCl combination (61 mg/ml) given at a dose of 0.75 ml/kg body weight. Following successful anesthesia, an ocular speculum (lid retractor) was put into place. The eye was steadied by gently grasping the palpebral conjunctiva with a pair of fine-toothed forceps. A 1 cc syringe containing test or control extract and attached to a 27 g needle was introduced into the anterior chamber of the eye. The needle was inserted about 0.5 cm into the anterior chamber at the corneal-scleral junction and parallel to the iris. A second syringe with 27 g needle was inserted at a remote point from the first. Approximately 0.2 ml of the aqueous fluid was evacuated immediately prior to injecting 0.2 ml of test or control extract via the first syringe. After the procedure, rabbits were returned to their cages and allowed to recover.
Three rabbits (Group III) received no treatment and served as negative controls.
Biomicroscope slit lamp examinations were conducted prior to treatment, at day one, day three, and termination (McDonald-Shaddock score system). Control animals were examined prior to treatment and at termination. Additionally, macroscopic observations of the eyes were conducted daily (Draize System); body weights were recorded prior to treatment and at termination; and on a representative number of eyes, tonometry readings (Schiotz tonometer) were taken before and after treatments.
After seven (7) days, the rabbits were killed by injection of T-61 Euthanasia Drug. The eyes were quickly removed and placed in 10% neutral buffered formalin for possible histological processing.
The results of slit lamp biomicroscope studies appear in Tables 15 and 16.
                                  TABLE 15
__________________________________________________________________________
SLIT LAMP EXAMINATION
       CONJUNCTIVA        CORNEA
       Conges-   Dis-
                     Aqueous              Floure-
Rabbit No.
       tion Swelling
                 charge
                     Flare
                          Iris
                              Pannus
                                  Opacity
                                       Area
                                          scein
__________________________________________________________________________
Lab No.   Interval:   Pre-treat
                         Examination By:
Group I
0558
    R  0    0    0   0    0   0   0    0  0
    L  0    0    0   0    0   0   0    0   1+
0803
    R  0    0    0   0    0   0   0    0  0
    L  0    0    0   0    0   0   0    0  0
0870
    R  0    0    0   0    0   0   0    0  0
    L  0    0    0   0    0   0   0    0  0
0871
    R  0    0    0   0    0   0   0    0  0
    L  0    0    0   0    0   0   0    0  0
0795
    R  0    0    0   0    0   0   0    0  0
    L  0    0    0   0    0   0   0    0  0
0868
    R  0    0    0   0    0   0   0    0   1+
    L  0    0    0   0    0   0   0    0  0
Group II
0817
    R  0    0    0   0    0   0   0    0  0
    L  0    0    0   0    0   0   0    0  0
0822
    R  0    0    0   0    0   0   0    0  0
    L  0    0    0   0    0   0   0    0  0
0806
    R  0    0    0   0    0   0   0    0  0
    L  0    0    0   0    0   0   0    0  0
0808
    R  0    0    0   0    0   0   0    0  0
    L  0    0    0   0    0   0   0    0   1+
0814
    R  0    0    0   0    0   0   0    0  0
    L  0    0    0   0    0   0   0    0  0
0824
    R  0    0    0   0    0   0   0    0   1+
    L  0    0    0   0    0   0   0    0  0
Group III
0809
    R  0    0    0   0    0   0   0    0  0
    L  0    0    0   0    0   0   0    0  0
0810
    R  0    0    0   0    0   0   0    0  0
    L  0    0    0   0    0   0   0    0   1+
0820
    R  0    0    0   0    0   0   0    0  0
    L  0    0    0   0    0   0   0    0  0
Lab No.   Interval:   Day 1
                         Examination By:
Group I - Exposed Material
0558
    R   1+  0    0   0     1+ 0   0    0
    L   2+  0    0   0     1+ 0   0    0
0803
    R   3+  0    0   0     2+ 0   0    0
    L   3+  0    0   0     2+ 0   0    0
0870
    R  0    0     2+ 0     1+ 0   0    0
    L   1+  0    0   0     1+ 0   0    0
0871
    R  0    0    0   0    0   0   0    0
    L  0    0    0   0    0   0   0    0
0795
    R   3+  0    0   0     1+ 0   0    0
    L  0    0    0   0     1+ 0   0    0
0868
    R    2+ 0     1+ 0     1+ 0   0    0
    L  0    0    0   0     1+ 0   0    0
Group II - Unexposed Material
0817
    R  0    0    0   0     1+ 0   0    0
    L   2+  0    0   0     1+ 0   0    0
0822
    R   2+  0    0   0     2+ 0   0    0
    L   2+  0    0   0     1+ 0   0    0
0806
    R   2+  0    0   0     2+ 0   0    0
    L   1+  0    0   0     1+ 0   0    0
0808
    R   3+  0    0   0     3+ 0   0    0
    L  0    0    0   0     1+ 0   0    0
0814
    R   2+  0    0   0     2+ 0   0    0
    L   1+  0    0   0    0   0   0    0
*0824
    R   4+  0    0   0     3+ 0   0    0
    L  0    0    0    1+   3+ 0   0    0
Lab No.   Interval:   Day 3
                         Examination By:
Group I - Exposed Material
0558
    R   2+  0    0    1+  0   0   0    0
    L   2+  0    0   0    0   0   0    0
0803
    R   2+  0    0   0     1+ 0   0    0
    L   1+  0    0   0     1+ 0   0    0
0870
    R   1+  0    0    1+  0   0   0    0
    L  0    0    0   0     1+ 0   0    0
0871
    R  0    0    0   0     1+ 0   0    0
    L   1+  0    0   0     1+ 0   0    0
0795
    R   1+  0    0    1+   1+ 0   0    0
    L   2+  0    0   0     1+ 0   0    0
0868
    R   1+  0    0   0     1+ 0   0    0
    L   1+  0    0   0    0   0   0    0
Group II - Unexposed Material
0817
    R   1+  0    0   0    0   0   0    0
    L   2+  0    0    1+  0   0   0    0
0822
    R   2+  0    0   0    0   0   0    0
    L   3+  0    0    2+  0   0   0    0
0806
    R   3+  0    0    1+   3+ 0   0    0
    L   3+  0    0    1+  0   0    1+  0
0808
    R   2+  0    0   0    0   0   0    0
    L   2+  0    0   0     1+ 0   0    0
0814
    R   2+  0    0   0     1+ 0   0    0
    L   2+  0    0   0    0   0   0    0
0824
    R   3+  0    0    1+   2+ 0   0    0
    L   4+  0    0    1+   3+ 0   0    0
Lab No.   Interval:  7-Day Terminal
                         Examination By:
Group I - Exposed Material
0558
    R  0    0    0   0    0   0   0    0  0
    L  0    0    0   0    0   0   0    0  0
0803
    R  0    0    0   0    0   0   0    0  0
    L   1+  0    0   0    0   0   0    0  0
0870
    R  0    0    0   0    0   0   0    0  0
    L  0    0    0   0    0    1+ 0    0  0
0871
    R  0    0    0   0    0   0   0    0  0
    L  0    0    0   0    0   0   0    0  0
0795
    R  0    0    0   0    0   0   0    0  0
    L  0    0    0   0    0   0   0    0  0
0868
    R  0    0    0   0    0   0   0    0  0
    L  0    0    0   0    0   0   0    0  0
Group II - Unexposed Material
0817
    R  0    0    0   0    0   0   0    0  0
    L   1+  0    0   0    0   0   0    0  0
0822
    R  0    0    0   0    0   0   0    0  0
    L  0    0    0   0    0   0   0    0  0
0806
    R  0    0    0   0    0   0   0    0  0
    L  0    0    0   0    0   0   0    0  0
0808
    R  0    0    0   0    0   0   0    0  0
    L  0    0    0   0    0   0   0    0  0
0814
    R  0    0    0   0    0   0   0    0  0
    L  0    0    0   0    0   0   0    0  0
0824
    R  0    0    0   0    0   0   0    0  0
    L  0    0    0   0    0   0   0    0  0
Group III - Negative Controls
0809
    R  0    0    0   0    0   0   0    0  0
    L  0    0    0   0    0   0   0    0   1+
0810
    R  0    0    0   0    0   0   0    0  0
    L  0    0    0   0    0   0   0    0  0
0820
    R  0    0    0   0    0   0   0    0  0
    L  0    0    0   0    0   0   0    0  0
__________________________________________________________________________
 R =  Right Eye
 L = Left Eye
 *Difficulties were encountered with the right eye at surgery which
 contributed to these findings.

              TABLE 16
______________________________________
ANTERIOR CHAMBER OBSERVATIONS
        Iris Ad-
        hered to
                Fibrinous
        Puncture
                Material
Group No. Day
Rabbit No.
          1     3     7   1   3   7   Other
______________________________________
I.   0558   R     --  X   --  --  --  --  Fold in corneal epithe-
            L     X   X   X   --  --  --  lium distorted pupil
                                          Day 3
     0803   R     X   X   --  --  X   --  Possible cataract start-
            L     X   X   X   --  --  X   ing in left eye
     0870   R     --  --  --  X   --  --  None
            L     X   X   X   --  --  --
     0871   R     --  X   X   --  --  --  Corneal irregularity
            L     --  X   --  --  --  --  day 3
     0795   R     X   X   --  X   --  --  None
            L     X   X   --  --  --  --
     0868   R     --  X   X   X   --  --  None
            L     X   X   X   --  --  --
II.  0817   R     X   X   --  --  --  --  Pupil distorted day 7
            L     X   X   --  --  --  --
     0822   R     X   X   --  X   --  --  None
            L     X   X   X   X   --  --
     0806   R     X   X   X   X   X   --  Possible cataract start-
            L     X   X   --  --  --  --  ing in right eye
     0808   R     X   X   --  X   --  --  None
            L     X   --  --  X   --  --
     0814   R     X   X   X   X   --  --  None
            L     --  X   --  --  X   --
     0824   R     --  X   X   X   X   X   Distorted Pupil
            L     X   X   X   X   X   X   Day 3, 7
______________________________________
 R = Right Eye (Test)
 L = Left Eye (Treated Control)
The McDonal-Shaddock score system used to prepare Tables 15 and 16 follows:
Conjunctival Congestion
0=Normal. May appear blanched to reddish pink without perilimbal injection (except at 12:00 and 6:00 o'clock positions) with vessels of the palpebral and bulbar conjunctiva easily observed (FIG. 2).
+1=A flushed, reddish color predominately confined to the palpebral conjunctival with some perilimbal injection, but primarily confined to the lower and upper parts of the eye from the 4:00 and 7:00 and 11:00 to 1:00 o'clock positions.
+2=Bright red color of the palpebral conjunctiva with accompanying perilimbal injection covering at least 75% of the circumference of the perilimbal region (FIG. 3).
+3=Dark, beefy red color with congestion of both the bulbar and the palpebral conjunctiva along with pronounced perilimbal injection and the presence of petechia on the conjunctiva. The petechia generally predominates along the nictitating membrane and the upper palpebral conjunctiva.
Conjunctival Swelling
0=Normal or no swelling of the conjunctival tissue.
+1=Swelling above normal without eversion of the lids (can be easily ascertained by noting that the upper and lower eyelids are positioned as in the normal eye); swelling generally starts in the lower cul-de-sac near the inner canthus, which needs slit-lamp examination.
+2=Swelling with misalignment of the normal approximation of the lower and upper eyelids; primarily confined to the upper eyelid so that in the initial stages the misapproximation of the eyelids begins by partial eversion of the upper eyelid (FIG. 2). In this stage, swelling is confined generally to the upper eyelid, although it exists in the lower cul-de-sac (observed best with the slit lamp).
+3=Swelling definite with partial eversion of the upper and lower eyelids essentially equivalent. This can be easily ascertained by looking at the animal head-on and noticing the positioning of the eyelids; if the eye margins do not meet, eversion has occurred.
+4=Eversion of the upper eyelid is pronounced with less pronounced eversion of the lower eyelid. It is difficult to retract the lids and observe the perilimbal region.
Conjunctival Discharge
Discharge is defined as a whitish, gray precipitate, which should not be confused with the small amount of clear, inspisated, mucoid material that can be formed in the medial canthus of a substantial number of rabbit eyes. This material can be removed with a cotton swab before the animals are used.
0=Normal. No discharge.
+1=Discharge above normal and present on the inner portion of the eye, but not on the lids or hairs of the eyelids. One can ignore the small amount that is in the inner and outer canthus if it has not been removed prior to starting the study.
+2=Discharge is abundant, easily observed, and has collected on the lids and around the hairs of the eyelids (FIG. 5).
+3=Discharge has been flowing over the eyelids so as to wet the hairs substantially on the skin around the eye.
Cornea
The scoring scheme measures the severity of corneal cloudiness and the area of the cornea involved. Severity of corneal coloudiness is graded as follows.
0=Normal cornea. Appears with the slit lamp as having a bright gray line on the epithelial surface and a bright gray line on the endothelial surface with a marblelike gray appearance of the stroma.
+1=Some loss of transparency. Only the anterior half of the stroma is involved as observed with an optical section of the slit lamp. The underlying structures are clearly visible with diffuse illumination, although some cloudiness can be readily apparent with diffuse illumination.
+2=Moderate loss of transparency. In addition to involving the anterior stroma, the cloudiness extends all the way to the endothelium. The stroma has lost its marblelike appearance and is homogeneously white. With diffuse illumination, underlying structures are clearly visible.
+3=Involvement of the entire thickness of the stroma. With optical section, the endothelial surface is still visible. However, with diffuse illumination, the underlying structures are just barely visible (to the extent that the observer is still able to grade flare, iritis, observe for pupillary response, and note lenticular changes).
+4=Involvement of the entire thickness of the stroma. With the optical section, cannot clearly visualize the endothelium. With diffuse illumination, the underlying structures cannot be seen. Cloudiness removes the capability for judging and grading aqueous flare, iritis, lenticular changes, and pupillary response.
The surface area of the cornea relative to the area of cloudiness is divided into five grades from 0 to +4.
0=Normal cornea with no area of cloudiness.
+1=1-25% area of stromal cloudiness.
+2=26-50% area of stromal cloudiness.
+3=51-75% area of stromal cloudiness.
+4=76-100% area of stromal cloudiness.
The use of fluorescein is a valuable aid in defining epithelial damage.
0=Absence of fluorescein staining.
+1=Slight fluorescein staining confined to a small focus. With diffuse illumination, the underlying structures are easily visible. (The outline of the pupillary margin is as if there were no fluorescein staining.)
+2=Moderate fluorescein staining confined to a small focus. With diffuse illumination, the underlying structures are clearly visible, although there is some loss of detail.
+3=Marked fluorescein staining. Staining may involve a larger portion of the cornea. With diffuse illumination, underlying structures are barely visible, but are not completely obliterated.
+4=Extreme fluorescein staining. With diffuse illumination, the underlying structures cannot be observed.
Aqueous Flare
The intensity of the Tyndall phenomenon is scored by comparing the normal Tyndall effect observed when the slit-lamp beam passes through the lens with that seen in the anterior chamber. The presence of aqueous flare is presumptive evidence of breakdown of the blood-aqueous barrier.
0=Absence of visible light beam light in the anterior chamber (no Tyndall effect).
1=The Tyndall effect is barely discernible. The intensity of the light beam in the anterior chamber is less than the intensity of the slit beam as it passes through the lens.
+2=The Tyndall beam in the anterior chamber is easily discernible and is equal in intensity to the slit beam as it passes through the lens.
+3=The Tyndall beam in the anterior chamber is easily discernible; its intensity is greater than the intensity of the slit beam as it passes through the lens.
Iris Involvement
In the following definitions, the primary, secondary, and tertiary vessels are utilized as an aid to determining a subjective ocular score for iris involvement. The assumption is made that the greater the hyperemia of the vessels and the more the secondary and tertiary vessels are involved, the greater the intensity of iris involvement. The scores range from 0 to +4.
0=Normal iris without any hyperemia of the iris vessels. Occasionally around the 12:00 to 1:00 o'clock position near the pupillary border and the 6:00 and 7:00 o'clock position near the pupillary border, there is a small area around 1-3 mm in diameter in which both the secondary and tertiary vessels are slightly hyperemic.
+1=Minimal injection of secondary vessels, but not tertiary. Generally, it is uniform, but may be of greater intensity at the 1:00 or 6:00 o'clock position. If it is confined to the 1:00 or 6:00 o'clock position, the tertiary vessels must be substantially hyperemic.
+2=Minimal injection of tertiary vessels and minimal to moderate injection of the secondary vessels.
+3=Moderate injection of the secondary and tertiary vessels with slight swelling of the iris stroma (this gives the iris surface a slightly rugose appearance, which is usually most prominent near the 3:00 and 9:00 o'clock positions).
+4=Marked injection of the secondary and tertiary vessels with marked swelling of the iris stroma. The iris appears rugose; may be accompanied by hemorrhage (hyphema) in the anterior chamber.
Pannus is vascularization or the penetration of new blood vessels into the corneal stroma. The vessels are derived from the limbal vascular loops. Pannus is divided into three grades.
0=No pannus.
+1=Vascularization is present, but vessels have not invaded the entire corneal circumference. Where localized vessel invasion has occurred, they have not penetrated beyond 2 mm.
+2=Vessels have invaded 2 mm or more around the entire corneal circumference.
As a result of the biomicroscopic study (Tables 15 and 16), no significant differences were noted between the test and control eyes of the treated animals. The anterior chamber of both eyes showed typical post-surgical changes such as iritis and an occasional aqueous flare. Observations were most acute at 24 hours after surgery. There were many cases of irido-corneal touch related to the injection procedure. The area of iris touch, in all cases, was to the healing injection sites. This observation was more prevalent at days 1 and 3.
A number of eyes had evidence of fibrinous material in the anterior chamber. This observation was believed to be related to surgical trauma.
One test eye and one control eye showed evidence of early cataract formation due to trauma.
Slight corneal scarring was noted at most needle puncture sites. At seven (7) days post-surgery, all changes had decreased significantly in severity and many eyes were quite normal in appearance. Some irido-corneal touch and pin-point corneal opacities were still present at the injection sites.
Macroscopic observations recorded daily appear in Table 17.
                                  TABLE 17
__________________________________________________________________________
MACROSCOPIC OBSERVATIONS
SUMMARY OF OCULAR SCORES
(Draize System)
                                     Test-Right
                                     Control-Left
                                     Lab No.
            Days:
            1     2     3     4   5   6  7
            T  C  T  C  T  C  T C T C T C T C
__________________________________________________________________________
Group I - (Exposed)
NO: 0558
Cornea (× 5)
            0  0  0  0  0  0  0 0 0 0 0 0 0 0
Iris Score (× 5)
            5  10 5  10 5  5  0 0 0 0 0 0 0 0
Conjunctiva Score (× 2)
            0  0  0  0  0  0  0 0 0 0 0 0 0 0
Total Score 5  10 5  10 5  5  0 0 0 0 0 0 0 0
NO: 0803
Cornea (× 5)
            0  0  0  0  0  0  0 0 0 0 0 0 0 0
Iris Score (× 5)
            10 10 10 10 10 5  5 5 5 5 0 0 0 0
Conjunctiva Score (× 2)
            0  0  0  0  0  0  0 0 0 0 0 0 0 0
Total Score 10 10 10 10 10 5  5 5 5 5 0 0 0 0
NO: 0870
Cornea (× 5)
            0  0  0  0  0  0  0 0 0 0 0 0 0 0
Iris Score (× 5)
            10 5  10 5  5  5  0 0 0 0 0 0 0 0
Conjunctiva Score (× 2)
            2  0  0  0  0  0  0 0 0 0 0 0 0 0
Total Score 12 5  10 5  5  5  0 0 0 0 0 0 0 0
NO: 0871
Cornea (× 5)
            0  0  0  0  0  0  0 0 0 0 0 0 0 0
Iris Score (× 5)
            0  0  0  0  0  0  0 0 0 0 0 0 0 0
Conjunctiva Score (× 2)
            0  0  0  0  0  0  0 0 0 0 0 0 0 0
Total Score 0  0  0  0  0  0  0 0 0 0 0 0 0 0
NO: 0795
Cornea (× 5)
            0  0  0  0  0  0  0 0 0 0 0 0 0 0
Iris Score (× 5)
            10 5  10 5  5  5  0 5 0 0 0 0 0 0
Conjunctiva Score (× 2)
            0  0  0  0  0  0  0 0 0 0 0 0 0 0
Total Score 10 5  10 5  5  5  0 5 0 0 0 0 0 0
NO: 0863
Cornea (× 5)
            0  0  0  0  0  0  0 0 0 0 0 0 0 0
Iris Score (× 5)
            5  5  5  5  5  5  0 0 0 0 0 0 0 0
Conjunctiva Score (× 2)
            0  0  0  0  0  0  0 0 0 0 0 0 0 0
Total Score 5  5  5  5  5  5  0 0 0 0 0 0 0 0
Group II - (Not Exposed)
NO: 0824
Cornea (× 5)
            0  0  0  0  0  0  0 0 0 0 0 0 0 0
Iris Score (× 5)
            10 10 10 10 5  10 5 5 5 5 5 5 0 0
Conjunctiva Score (× 2)
            0  0  0  0  0  0  0 0 0 0 0 0 0 0
Total Score 10 10 10 10 5  10 5 5 5 5 5 5 0 0
NO: 0817
Cornea (× 5)
            0  0  0  0  0  0  0 0 0 0 0 0 0 0
Iris Score (× 5)
            5  5  5  5  5  0  0 0 0 0 0 0 0 0
Conjunctiva Score (× 2)
            0  0  0  0  0  0  0 0 0 0 0 0 0 0
Total Score 5  5  5  5  5  0  0 0 0 0 0 0 0 0
NO: 0822
Cornea (× 5)
            0  0  0  0  0  0  0 0 0 0 0 0 0 0
Iris Score (× 5)
            0  0  0  0  0  0  0 0 0 0 0 0 0 0
Conjunctiva Score (× 2)
            0  0  0  0  0  0  0 0 0 0 0 0 0 0
Total Score 0  0  0  0  0  0  0 0 0 0 0 0 0 0
NO: 0806
Cornea (× 5)
            0  0  0  0  0  0  0 0 0 0 0 0 0 0
Iris Score (× 5)
            5  0  5  0  10 0  5 0 5 0 0 0 0 0
Conjunctiva Score (× 2)
            0  0  0  0  0  0  0 0 0 0 0 0 0 0
Total Score 5  0  5  0  10 0  5 0 5 0 0 0 0 0
NO: 0808
Cornea (× 5)
            0  0  0  0  0  0  0 0 0 0 0 0 0 0
Iris Score (× 5)
            10 5  10 5  5  5  0 0 0 0 0 0 0 0
Conjunctiva Score (× 2)
            0  0  0  0  0  0  0 0 0 0 0 0 0 0
Total Score 10 5  10 5  5  5  0 0 0 0 0 0 0 0
NO: 0814
Cornea (× 5)
            0  0  0  0  0  0  0 0 0 0 0 0 0 0
Iris Score (× 5)
            5  5  5  5  0  0  5 0 0 0 0 0 0 0
Conjunctiva Score (× 2)
            0  0  0  0  0  0  0 0 0 0 0 0 0 0
Total Score 5  5  5  5  0  0  5 0 0 0 0 0 0 0
Group III - Sham-Control
NO: 0809
Cornea (× 5)
            0  0  0  0  0  0  0 0 0 0 0 0 0 0
Iris Score (× 5)
            0  0  0  0  0  0  0 0 0 0 0 0 0 0
Conjunctiva Score (× 2)
            0  0  0  0  0  0  0 0 0 0 0 0 0 0
Total Score 0  0  0  0  0  0  0 0 0 0 0 0 0 0
NO: 0810
Cornea (× 5)
            0  0  0  0  0  0  0 0 0 0 0 0 0 0
Iris Score (× 5)
            0  0  0  0  0  0  0 0 0 0 0 0 0 0
Conjunctiva Score (× 2)
            0  0  0  0  0  0  0 0 0 0 0 0 0 0
Total Score 0  0  0  0  0  0  0 0 0 0 0 0 0 0
NO: 0820
Cornea (× 5)
            0  0  0  0  0  0  0 0 0 0 0 0 0 0
Iris Score (× 5)
            0  0  0  0  0  0  0 0 0 0 0 0 0 0
Conjunctiva Score (× 2)
            0  0  0  0  0  0  0 0 0 0 0 0 0 0
Total Score 0  0  0  0  0  0  0 0 0 0 0 0 0 0
__________________________________________________________________________
The scale used for scoring ocular lesions as listed in Table 17 is as follows:
______________________________________
(1)  Cornea
(A)     Opacity-degree of density (area most dense
        taken for reading)
        No opacity                0
        Scattered or diffuse area, details
                                  1
        of iris clearly visible
        Easily discernible translucent areas,
                                  2
        details of iris slightly obscured
        Opalescent areas, no details of iris
                                  3
        visible, size of pupil barely
        discernible
        Opaque, iris invisible    4
(B)     Area of cornea involved
        One quarter (or less) but not zero
                                  1
        Greater than one quarter, but less
        than half
        Greater than half, but less than
                                  3
        three quarters
        Greater than three quarters, up to
                                  4
        a whole area
Score equals A × B × 5
                  Total maximum = 80
(2)  Iris
(A)     Values
        Normal                    0
        Folds above normal, congestion,
                                  1
        swelling, circumcorneal injection
        (any or all of these or combination
        of any thereof) iris still reacting
        to light (sluggish reactions are
        positive)
        No reaction to light, hemorrhage,
                                  2
        gross destruction (any or all
        of these)
Score equals A × 5
                  Total maximum = 10
(3)  Conjunctivae
(A)     Redness (refers to palpebral and bulbar
        conjunctivae excluding cornea and iris)
        Vessels normal            0
        Vessels definitely injected above
                                  1
        normal
        More diffuse, deeper crimson red,
                                  2
        individual vessels not easily
        discernible
        Diffuse beefy red         3
(B)     Chemosis
        No swelling               0
        Any swelling above normal (includes
                                  1
        nictitating membrane)
        Obvious swelling with partial
                                  2
        eversion of lids
        Swelling with lids about half closed
                                  3
        Swelling with lids half closed to
                                  4
        completely closed
(C)     Discharge
        No discharge              0
        Any amount different from normal
                                  1
        (does not include small amounts
        observed in inner canthus of
        normal animals)
        Discharge with moistening of the
                                  2
        lids and hairs adjacent to lids
        Discharge with moistening of the
                                  3
        lids and hairs and considerable
        area around the eye
Score equals A + B + C × 2
                  Total maximum = 20
______________________________________
 The maximum total score is the sum of all scores obtained for the cornea,
 iris, and conjunctivae. Total maximum score possible = 110.
Iritis was the significant observation noted during the macroscopic observations. As the post-operative period progressed, the iritis diminished. At seven (7) days, the gross appearance of the majority of the eyes was similar to the non-treated control group.
Body weights of the test rabbits recorded prior to treatment and at 7 days indicated no appreciable weight loss during the study. Animals remained healthy throughout.
Tonometry readings (Schiotz with standard 5.5 g wt) taken prior to and after treatment indicated that the removal and instillation of approximately equal volumes of fluid caused an immediate increase in intraocular pressure. There was some evidence that the ocular pressure had returned to normal by 7 days, but the influence of general anesthetics and/or euthanasia drug was not determined. The results of the tonometry readings are in Table 18.
              TABLE 18
______________________________________
           At Surgery
                    At Termination
Group Rabbit No. Pre    Post  Anesthetized
                                       Euthanized
______________________________________
I     0558   R       N.T. 20+   N.T.     12.0
             L       4.5  20+   N.T.     10.0
      0803   R       6.5  20+   N.T.      5.0
             L       5.0  20+   N.T.      3.0
      0870   R       6.5  20+   N.T.     11.0
             L       8.0  20+   N.T.     10.0
II    0817   R       6.0  20+   6.0      11.0
             L       N.T. 20+   4.5       6.0
      0822   R       7.0  20+   4.5      12.0
             L       N.T. 20+   4.5      14.0
      0808   R       5.5  20+   N.T.     N.T.
             L       6.0  20+   N.T.     N.T.
______________________________________
 N.T. = Not taken.
 R = Right eye.
 L = Left eye.
EXAMPLE 12 CYTOTOXICITY-MEM ELUTION-MG 23
A monolayer of L-929 Mouse Fibroblast cells was grown to confluency and exposed to an extract of a test sample prepared by placing material prepared in accordance with Example 1 (test material) in 20 ml of Minimum Essential Medium (Eagle) and bovine serum (5%) and extracting at 37° C. for 24 hours. An MEM aliquot was used as a negative control. After exposure to the extract, the cells were examined microscopically for cytotoxic effect (CTE). Cytotoxicity was scored as either Non-Toxic (N), Intermediate (I), or Toxic (T).
N=Indicates a negative or non-toxic response;
I=Indicates an intermediate response, a subjective assessment of the extent of cellular response; and
T=Indicates a positive or toxic response consisting of greater than 50% cell death.
The results are listed in Table 19.
              TABLE 19
______________________________________
OBSERVATION PERIOD
         24 Hours  48 Hours 72 Hours
______________________________________
Test Material
           N           N        N
Control    N           N        N
______________________________________
 Comments:
 Positive control toxic at 24 hours.
The results indicate that all samples were non-toxic.
EXAMPLE 13 CYTOTOXICITY-AGAR OVERLAY-MG 26
A monolayer of L-929 Mouse Fibroblast cells was grown to confluency and overlaid with Medium 199 supplemented with serum, antibiotics, neutral red, and agar. An intraocular lens comprising material prepared in accordance with Example 1 (test material) was placed on the solidified overlay surface. Following incubation for 24 hours, the culture was macroscopically examined for evidence of cell decolorization to determine the zone of cell lysis. Any decolorized zone present was examined microscopically to confirm cell lysis. The results are listed in Table 20.
              TABLE 20
______________________________________
               Score Zone of Lysis (mm)
______________________________________
Test Material    N       --
Negative Control (USP
                 N       --
Negative Control
Plastic)
Positive Control T       9
(Latex)
______________________________________
 N (Nontoxic) No change in cell morphology in proximity to test sample.
 T (Toxic) Death and/or degeneration of cells directly beneath the area of
 test sample and possibly also within a zone extended beyond the test
 sample. Where a zone of lysis was observed, the distance from the edge of
 the sample to the edge of the zone  measured and reported in millimeters
 (mm).
The results indicate that the test material is non-toxic for L-929 cells under the above described test conditions.
EXAMPLE 14 CYTOTOXICITY-AGAR OVERLAY-MG 26
A monolayer of L-929 Mouse Fibroblast cells was grown to confluency and overlaid with Medium 199 supplemented with serum, antibiotics, neutral red, and agar. A 1 cm2 sheet of material prepared in accordance with Example 1 (test material) was placed on the solidified overlay surface. Following incubation for 24 hours, the culture was macroscopically examined for evidence of cell decolorization to determine the zone of cell lysis. Any decolorized zone present was examined microscopically to confirm cell lysis. The results are listed in Table 21.
              TABLE 21
______________________________________
               Score Zone of Lysis (mm)
______________________________________
Test Material    N       --
Negative Control (USP
                 N       --
Negative Control
Plastic)
Positive Control (Latex)
                 T       8
______________________________________
 N (Nontoxic) No change in cell morphology in proximity to test sample.
 T (Toxic) Death and/or degeneration of cells directly beneath the area of
 test sample and possibly also within a zone extended beyond the test
 sample. Where a zone of lysis was observed, the distance from the edge of
 the sample to the edge of the zone was measured and reported in
 millimeters (mm).
The results indicate that the test material is non-toxic for L-929 cells under the above described conditions.
EXAMPLE 15 HEMOLYSIS TEST (EXTRACT)
90 square centimeters of material prepared in accordance with Example 1 (test material) was placed in 30 ml of sodium chloride solution (0.9%) and extracted at 121° C. for 1 hour. The extract was divided into two tubes of 10 ml each.
To each tube was added 0.2 ml of human blood previously collected in a vacuum tube containing E.D.T.A. Tubes were inverted gently to mix the contents, then placed in a constant temperature water bath at 37° C. for 1 hour. The blood silane mixture was then transferred to a new set of tubes and centrifuged for 5 minutes at 1,500 RPM. The supernatant liquid was aspirated into a second tube and centrifuged again.
The optical density of each sample solution was determined spectrophotometrically at 545 mμ. Similarly, optical densities were recorded for a positive control (10 ml water and 0.2 ml blood) and a negative control (10 ml Sodium Chloride and 0.2 ml blood). The results are listed in Table 22.
              TABLE 22
______________________________________
Negative Control = 0
                 absorbance = 0% hemolysis.
Positive Control = 1.699
                 absorbance = 100% hemolysis.
Test #1 = 0      absorbance = 0% hemolysis.
Test #2 = 0      absorbance = 0% hemolysis.
______________________________________
 Mean Hemolysis 0%.
The results indicated that the test material is non-hemolytic under conditions of this test.
EXAMPLE 16 HEMOLYSIS TEST (DIRECT) Sterilized Test Material
Material prepared in accordance with Example 1 (test material) was sterilized with ethylene oxide and cut into small chips or lengths (3 cm×0.5 cm). 2 grams of the test material were placed in each of two extracting tubes containing 10 ml of sodium chloride solution (0.9%).
To each tube was added 0.2 ml of human blood previously collected in a vacuum tube containing E.D.T.A. Tubes were inverted gently to mix the contents, then placed in a constant temperature water bath at 37° C. for 1 hour. The blood saline mixture was then transferred to a new set of tubes and centrifuged for 5 minutes at 1,500 RPM. The supernatant liquid was aspirated into a second tube and centrifuged again.
The optical density of each sample solution was determined spectrophotometrically at 545 mμ. Similarly, optical densities were recorded for a positive control (10 ml water and 0.2 ml blood) and a negative control (10 ml Sodium Chloride and 0.2 ml blood). The results are listed in Table 23.
              TABLE 23
______________________________________
Negative Control = 0
                 absorbance = 0% hemolysis.
Positive Control = 1.699
                 absorbance = 100% hemolysis.
Test #1 = 0.009  absorbance = 0.5% hemolysis.
Test #2 = 0.004  absorbance = 0.2% hemolysis.
______________________________________
 Mean hemolysis 0.4%.
The results indicated that the test material is non-hemolytic under conditions of the test.
EXAMPLE 17 HEMOLYSIS TEST (DIRECT) FINISHED LENS
An intraocular lens comprising prepared in accordance with Example 1 (test material) was cut in half. Each half was placed in a separate extracting tube containing 10 ml of sodium chloride solution (0.9%).
To each tube was added 0.2 ml of human blood previously collected in a vacuum tube containing E.D.T.A. Tubes were inverted gently to mix the contents, then placed in a constant temperature water bath at 37° C. for 1 hour. The blood saline mixture was then transferred to a new set of tubes and centrifuged for 5 minutes at 1,500 RPM. The supernatant liquid was aspirated into a second tube and centrifuged again.
The optical density of each sample solution was determined spectrophotometrically at 545 mμ. Similarly, optical densities were recorded for a positive control (10 ml water and 0.2 ml blood) and a negative control (10 ml Sodium Chloride and 0.2 ml blood). The results are listed in Table 24.
              TABLE 24
______________________________________
Negative Control = 0
                 absorbance = 0% hemolysis.
Positive Control = 1.699
                 absorbance = 100% hemolysis.
Test #1 = 0.004  absorbance = 0.2% hemolysis.
Test #2 = 0.009  absorbance = 0.5% hemolysis.
______________________________________
 Mean Hemolysis 0.4%.
The results indicated that the test material is non-hemolytic under conditions of the test.
EXAMPLE 18 HEMOLYSIS TEST (DIRECT) (Non-sterilized test material)
Material prepared in accordance with Example 1 (test material) was cut into small chips or lengths (3 cm×0.5 cm) and two grams of the material was placed into each of two extracting tubes containing 10 ml of sodium chloride solution (0.9%).
To each tube was added 0.2 ml human blood previously collected in a vacuum tube containing E.D.T.A. Tubes were inverted gently to mix the contents, then placed in a constant temperature water bath at 37° C. for 1 hour. The blood saline mixture was then transferred to a new set of tubes and centrifuged for 5 minutes at 1,500 RPM. The supernatant liquid as aspirated into a second tube and centrifuged again.
The optical density of each sample solution was determined spectrophotometrically at 545 mμ. Similarly, optical densities were recorded for a positive control (10 ml water and 0.2 ml blood) and a negative control (10 ml Sodium Chloride and 0.2 ml blood). The results are listed in Table 25.
              TABLE 25
______________________________________
Negative Control = 0
                 absorbance = 0% hemolysis.
Positive Control = 1.699
                 absorbance = 100% hemolysis.
Test #1 = 0      absorbance = 0% hemolysis.
Test #2 = 0      absorbance = 0% hemolysis.
______________________________________
 Mean Hemolysis 0%.
The results indicated that the test material is non-hemolytic under conditions of the test.
EXAMPLE 19 MUTAGENICITY SCREEN
Material prepared in accordance with Example 1 (test material) were tested for their ability to cause mutagenic response in bacterial tester stains with and without the presence of an enzomatic activation system. The results of the test are in Table 26.
              TABLE 26
______________________________________
I. Spontaneous Mutation Rate
Strain       Revertants/Plate
______________________________________
TA 98        26
TA 100       198
TA 1537      11
______________________________________
II. Mutagen Test
                   Dose/
Strain Sample      Plate    S-9 Mix
                                   Evaluation
______________________________________
TA 98  Unknown     10    mm.sup.2
                              +      Non-mutagenic
TA 100 Unknown     10    mm.sup.2
                              +      Non-mutagenic
TA 1537
       Unknown     10    mm.sup.2
                              +      Non-mutagenic
TA 98  Unknown     10    mm.sup.2
                              -      Non-mutagenic
TA 100 Unknown     10    mm.sup.2
                              -      Non-mutagenic
TA 1537
       Unknown     10    mm.sup.2
                              -      Non-mutagenic
benzopyreneha.
       10          μg +    Mutagenic
benzopyreneha.
       10          μg +    Mutagenic
TA 1537
       α-benzopyrene
                   10    μg
                              +      Mutagenic
______________________________________
The conclusion, based on the test results, is that no evidence was found indicating that the test material is mutagenic.
EXAMPLE 20 CELL GROWTH INHIBITION
Nine sample weights of material prepared in accordance with Example 1 (test material) were extracted in distilled water in the following ratios: 4,000 mg/20 ml, 500 mg/20 ml, 100 mg/20 ml, 50 mg/20 ml, 4 mg/20 ml, 3 mg/20 ml, 2 mg/20 ml, 1 mg/20 ml, 1 mg/40 ml. Each sample was extracted at 121° C. for one hour.
For each extract, fifteen mls of each extract was aseptically added to fifteen ml of double strength Minimal Essential Medium (2XMEM) in a sterile container. For each extract, two ml was added to ten assay tubes containing 0.2 ml of L-929 Mouse Fibroblast cells previously adjusted to 106 cells/ml, then mixed. Ten additional tubes were prepared similarly as controls, substituting distilled water for sample extract solution. Half of the extract treated tubes and half of the control tubes were immediately incubated at 37° C. for 72 hours. The remaining tubes were centrifuged and the medium decanted. The cells were resuspended in sterile Phosphate Buffered Saline (PBS), centrifuged, and the PBS decanted. The cells were resuspended, centrifuged, and decanted twice again, then stored for 72 hours at 4° C. At the end of the incubation period, the tubes at 37° C. were washed in the same manner as the refrigerated tubes. All tubes were assayed for protein content using a phenol reagent and measuring the degree of color development with the aid of a spectrophotometer. The average Optical Density (O. D.) of each set of five replicate tubes was determined and the percent of inhibition of cell growth was calculated as follows: ##EQU1##
The results are listed in Table 27.
              TABLE 27
______________________________________
Extract        Percent of Cell Growth Inhibition
______________________________________
1.   4,000   mg/20 ml  0
2.   500     mg/20 ml  0
3.   100     mg/20 ml  0
4.   50      mg/20 ml  0
5.   4       mg/20 ml  0
6.   3       mg/20 ml  0
7.   2       mg/20 ml  0
8.   1       mg/20 ml  0
9.   1       mg/40 ml  0
______________________________________
The precision of the assay is approximately ±10%. That is, the range of values expected for a non-toxic biomaterial in the nine point percent ICG assay would fall between ±10% inhibition. All nine extracts fall within this range and, therefore, do not produce inhibition of cell growth.
The above described leaching and in-vivo and in-vitro biological studies indicated that a PMMA/PERMASORB MA co-polymer material prepared in accordance with Example 1 is biocompatible with body tissue and fluids. Thus, an intraocular lens comprising such a material provided in accordance with practice of this invention is suitable for implantation into the eye.
EXAMPLE 21 RADIATION TRANSMITTANCE COMPARISON
PMMA/PERMASORB MA co-polymer materials prepared in accordance with Example 1 were also tested for transmittance of radiation and were compared to: (1) a standard intraocular lens formed of PMMA; (2) a human lens (age 22 years); and (3) a human lens (age 53 years). The results are listed below in Table 28.
              TABLE 28
______________________________________
TRANSMITTANCE OF ULTRAVIOLET LIGHT ABSORB-
ING INTRAOCULAR LENS MATERIAL PREPARED
ACCORDING TO EXAMPLE 1 WITH COMPARISONS
                  UV Absorbing
                  Lens Material
      Pure        Prepared    Human   Human
Wave- PMMA Lens   According to
                              Lens    Lens
length
      Material    Example 1   (22 yrs)
                                      (53 yrs)
(mm)  (1)         (2)         (3)     (4)
______________________________________
UV-A
320   88%         <1.0%       <1.0%   <1.0%
330   89%         <1.0%       <1.0%   <1.0%
340   89%         <1.0%       <1.0%   <1.0%
350   90%         <1.0%       <1.0%   <1.0%
360   91%         <1.0%       <1.0%   <1.0%
370   91%         <1.0%       <1.0%   <1.0%
380   91%         <1.0%       <1.0%   <1.0%
390   92%         1.5%        5.0%    <1.0%
395   92%         6.0%        10.0%    2.0%
400   92%         18.0%       15.0%    5.0%
Visual
450   92%         88.0%       85.0%   *
500   92%         92.0%       93.0%   *
550   92%         92.0%       95.0%   *
600   92%         92.0%       95.0%   *
650   92%         92.0%       95.0%   *
700   92%         92.0%       95.0%   *
______________________________________
 (1) Direct transmittance of PMMA sample 1.05 mm thick.
 (2) Direct transmittance of UV absorbing lens material .92 mm thick
 prepared according to the Example.
 (3) Direct transmittance of human lens 22 years.
 (4) Direct transmittance of human lens 53 years up to 400 nm; data not
 available over 400 nm.
As can be seen from Table 28, the UV absorbing lens material prepared in accordance with Example 1 has a capability to absorb ultraviolet radiation that is similar to the ultraviolet absorbing capability of a natural human lens.
In another embodiment of practice of this invention, a homopolymer of such a polymerizable chromophoric compound described above can also be formed, comminuted, and mixed with methyl methacrylate monomer, which is then polymerized to form the ultraviolet radiation absorbing lens of this invention. The molecular weight of the homopolymer must be sufficiently high to inhibit leaching. Leaching can also be inhibited or prevented by addition of cross-linking agents such as ethylene glycol dimethacrylate to the methyl methacrylate monomer/homopolymer mixture.
Although this invention has been described in detail with particular attention to certain preferred embodiments thereof, it will be understood that variations and modifications can be effected within the spirit and scope of the invention. The scope of the invention is defined in the following claims.

Claims (6)

What is claimed is:
1. A method for forming an intraocular lens comprising the steps of:
(a) co-polymerizing a polymerizable derivative of dihydroxybenzophenone and methyl methacrylate monomer to form a solid ultraviolet radiation absorbing co-polymer additive;
(b) dissolving the ultraviolet radiation absorbing co-polymer additive in methyl methacrylate monomer to thereby form a prepolymer solution;
(c) curing the prepolymer solution in a mold to thereby form an intraocular lens comprising the ultraviolet radiation absorbing co-polymer additive physically trapped within a polymethylmethacrylate polymer matrix.
2. The method according to claim 1 wherein the polymerizable derivative is a derivative of 2,4-dihydroxybenzophenone.
3. The method according to claim 2 wherein the solid co-polymer additive comprises less than about 15% by weight of the polymerizable derivative of 2,4-dihydroxybenzophenone.
4. The method according to claim 2 wherein the derivative of 2,4-dihydroxybenzophenone comprises between about four percent and about five percent by weight of the total weight of the lens.
5. An intraocular lens for implantation into the human eye comprising an ultraviolet radiation absorbing co-polymer physically trapped within a polymethylmethacrylate polymer matrix, said lens being formed by the steps of:
(a) co-polymerizing a polymerizable derivative of dihydroxybenzophenone with methyl methacrylate monomer to thereby form an ultraviolet radiation absorbing co-polymer additive;
(b) dissolving the ultraviolet radiation absorbing co-polymer additive in methyl methacrylate monomer to thereby form a prepolymer solution;
(c) curing the prepolymer solution in a mold to thereby form an intraocular lens comprising the ultraviolet radiation absorbing co-polymer additive physically trapped within a polymethylmethacrylate polymer matrix.
6. An intraocular lens for implantation into the human eye according to claim 5, wherein the polymerizable derivative is a derivative of 2,4-dihydroxybenzophenone.
US06/713,014 1982-05-10 1985-03-18 Ultraviolet radiation absorbing intraocular lens Expired - Fee Related US4636212A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
US06/713,014 US4636212A (en) 1982-05-10 1985-03-18 Ultraviolet radiation absorbing intraocular lens
US06/948,328 US4753654A (en) 1985-03-18 1986-12-31 Ultraviolet radiation absorbing intraocular lens

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US37666682A 1982-05-10 1982-05-10
US06/713,014 US4636212A (en) 1982-05-10 1985-03-18 Ultraviolet radiation absorbing intraocular lens

Related Parent Applications (1)

Application Number Title Priority Date Filing Date
US37666682A Continuation-In-Part 1982-05-10 1982-05-10

Related Child Applications (1)

Application Number Title Priority Date Filing Date
US06/948,328 Continuation US4753654A (en) 1985-03-18 1986-12-31 Ultraviolet radiation absorbing intraocular lens

Publications (1)

Publication Number Publication Date
US4636212A true US4636212A (en) 1987-01-13

Family

ID=27007498

Family Applications (1)

Application Number Title Priority Date Filing Date
US06/713,014 Expired - Fee Related US4636212A (en) 1982-05-10 1985-03-18 Ultraviolet radiation absorbing intraocular lens

Country Status (1)

Country Link
US (1) US4636212A (en)

Cited By (52)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4740070A (en) * 1984-06-05 1988-04-26 Ppg Industries, Inc. Optical filter
US4753654A (en) * 1985-03-18 1988-06-28 Optical Radiation Corporation Ultraviolet radiation absorbing intraocular lens
US4765977A (en) * 1986-11-28 1988-08-23 Baron Neville A Ophthalmic liquid sunglasses
US4788007A (en) * 1986-11-28 1988-11-29 Baron Neville A Ophthalmic U.V. absorptive emollient
WO1988009663A1 (en) * 1987-06-09 1988-12-15 Mdr Group, Inc. Viscoelastic vitreous substitute with uv blocker
US4795461A (en) * 1985-07-19 1989-01-03 Pharmacia Ab UV absorbing lens material
US4861840A (en) * 1986-12-03 1989-08-29 Barnes-Hind, Inc. Novel siloxanyl acrylic monomer and gas-permeable contact lenses made therefrom
US4863463A (en) * 1987-12-21 1989-09-05 Tjan Tik T Artificial intra-ocular lens for implantation in the capsular bag
US4863466A (en) * 1986-04-01 1989-09-05 Schlegel Hans Joachim Intra-ocular implant lens
US4872877A (en) * 1987-03-17 1989-10-10 Dennis T. Grendahl Intraocular lens with ultraviolet screening agent
US4872878A (en) * 1987-03-17 1989-10-10 Dennis T. Grendahl Optical brigthener in an intraocular lens
EP0359829A1 (en) * 1988-03-03 1990-03-28 Hoya Corporation Process for producing intraocular lens for correcting cyanopia
US5008102A (en) * 1986-02-26 1991-04-16 York Kenneth K Biocompatible intraocular light-screening compositions and methods of intraocular light screening
US5037435A (en) * 1990-03-02 1991-08-06 Optical Radiation Corporation Haptics for intraocular lenses having high fracture toughness
US5089180A (en) * 1989-08-31 1992-02-18 Iolab Corporation Method of preparing composite single-piece intraocular lenses with colored haptics
EP0589809A1 (en) * 1992-09-04 1994-03-30 Laboratoires Domilens S.A. Intra-ocular implant for spectral restoration or correction
US5364256A (en) 1986-01-28 1994-11-15 Ophthalmic Research Group International, Inc. Apparatus for the production of plastic lenses
US5415816A (en) 1986-01-28 1995-05-16 Q2100, Inc. Method for the production of plastic lenses
US5480927A (en) * 1994-05-20 1996-01-02 Ciba Geigy Corporation Method of increasing the concentration of radiation-absorbing agents in optical and ophthalmic lenses
US5514214A (en) 1993-09-20 1996-05-07 Q2100, Inc. Eyeglass lens and mold spin coater
US5529728A (en) 1986-01-28 1996-06-25 Q2100, Inc. Process for lens curing and coating
US5562734A (en) * 1995-05-31 1996-10-08 Zimmer, Inc. Method for reducing gamma radiation sterilization induced discoloration
US5683456A (en) * 1988-10-26 1997-11-04 Pharmacia, Inc. Fabrication of an intraocular lens
WO1997041806A1 (en) * 1996-05-09 1997-11-13 Prism Ophthalmics Prismatic intraocular lenses and related methods of using such lenses to restore vision in patients with central field loss
US5928575A (en) 1996-04-19 1999-07-27 Q2100, Inc. Methods for eyeglass lens curing using ultraviolet light
US5968094A (en) * 1995-09-18 1999-10-19 Emmetropia, Inc. Compound intraocular lens
US6201037B1 (en) 1986-01-28 2001-03-13 Ophthalmic Research Group International, Inc. Plastic lens composition and method for the production thereof
US6244707B1 (en) 1998-07-21 2001-06-12 Wesley Jessen Corporation UV blocking lenses and material containing benzotriazoles and benzophenones
US6280171B1 (en) 1996-06-14 2001-08-28 Q2100, Inc. El apparatus for eyeglass lens curing using ultraviolet light
US6441119B1 (en) 1999-09-20 2002-08-27 Hoya Corporation Optical materials having good ultraviolet absorbability and method for producing them
US6448304B1 (en) 1999-09-20 2002-09-10 Hoya Corporation Optical materials having good ultraviolet absorbability and method for producing them
WO2004029675A1 (en) * 2002-09-25 2004-04-08 Medennium, Inc. Method of manufacturing ophthalmic lenses made from hydrophobic acrylic polymers
US6730244B1 (en) 1986-01-28 2004-05-04 Q2100, Inc. Plastic lens and method for the production thereof
US20050033420A1 (en) * 2003-05-28 2005-02-10 Bruce A. Christie Mask configured to maintain nutrient transport without producing visible diffraction patterns
US20050143812A1 (en) * 2003-12-29 2005-06-30 Paul Marlene L. Intraocular lenses having a visible light-selective-transmissive-region
US20060122349A1 (en) * 2004-12-07 2006-06-08 Key Medical Technologies, Inc. Nanohybrid polymers for ophthalmic applications
US20060203192A1 (en) * 1999-03-01 2006-09-14 David Miller System and method for increasing the depth of focus of the human eye
US20060235514A1 (en) * 2005-04-14 2006-10-19 Silvestrini Thomas A Corneal optic formed of degradation resistant polymer
US20060271027A1 (en) * 2003-06-17 2006-11-30 Thomas Silvestrini Method and apparatus for aligning a mask with the visual axis of an eye
US7354980B1 (en) 2004-03-12 2008-04-08 Key Medical Technologies, Inc. High refractive index polymers for ophthalmic applications
US20080182957A1 (en) * 2004-11-22 2008-07-31 Jason Clay Pearson Copolymerizable azo compounds and articles containing them
US20080215147A1 (en) * 2007-01-29 2008-09-04 Werblin Research & Development Corp. Intraocular lens system
US20090076235A1 (en) * 2004-11-22 2009-03-19 Jason Clay Pearson Copolymerizable methine and anthraquinone compounds and articles containing them
US20100085534A1 (en) * 2004-04-30 2010-04-08 Abbott Medical Optics Inc. Ophthalmic devices having a highly selective violet light transmissive filter and related methods
US20110040378A1 (en) * 2007-01-29 2011-02-17 Werblin Research & Development Corp. Intraocular lens system
US20110040376A1 (en) * 2009-08-13 2011-02-17 Acufocus, Inc. Masked intraocular implants and lenses
US8066769B2 (en) 2007-01-29 2011-11-29 Werblin Research & Development Corp. Intraocular lens system
US8066768B2 (en) 2007-01-29 2011-11-29 Werblin Research & Development Corp. Intraocular lens system
USD656526S1 (en) 2009-11-10 2012-03-27 Acufocus, Inc. Ocular mask
US9204962B2 (en) 2013-03-13 2015-12-08 Acufocus, Inc. In situ adjustable optical mask
US9427922B2 (en) 2013-03-14 2016-08-30 Acufocus, Inc. Process for manufacturing an intraocular lens with an embedded mask
US9545303B2 (en) 2011-12-02 2017-01-17 Acufocus, Inc. Ocular mask having selective spectral transmission

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3162676A (en) * 1962-06-18 1964-12-22 Nat Starch Chem Corp Ethylenically unsaturated derivatives of 2, 4-dihydroxybenzophenone
US4390676A (en) * 1976-11-15 1983-06-28 Schering Corporation Ultraviolet absorbing lenses

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3162676A (en) * 1962-06-18 1964-12-22 Nat Starch Chem Corp Ethylenically unsaturated derivatives of 2, 4-dihydroxybenzophenone
US3173893A (en) * 1962-06-18 1965-03-16 Nat Starch Chem Corp Polymeric compositions resistant to ultra-violet light containing benzophenone derivatives
US4390676A (en) * 1976-11-15 1983-06-28 Schering Corporation Ultraviolet absorbing lenses

Cited By (123)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4740070A (en) * 1984-06-05 1988-04-26 Ppg Industries, Inc. Optical filter
US4753654A (en) * 1985-03-18 1988-06-28 Optical Radiation Corporation Ultraviolet radiation absorbing intraocular lens
US4795461A (en) * 1985-07-19 1989-01-03 Pharmacia Ab UV absorbing lens material
US6331058B1 (en) 1986-01-28 2001-12-18 Ophthalmic Research Group International, Inc. Plastic lens composition and method for the production thereof
US6494702B1 (en) 1986-01-28 2002-12-17 Q2100, Inc. Apparatus for the production of plastic lenses
US6206673B1 (en) 1986-01-28 2001-03-27 Ophthalmic Research Group International, Inc. Plastic lens and plastic lens manufacturing system
US6730244B1 (en) 1986-01-28 2004-05-04 Q2100, Inc. Plastic lens and method for the production thereof
US5529728A (en) 1986-01-28 1996-06-25 Q2100, Inc. Process for lens curing and coating
US5516468A (en) 1986-01-28 1996-05-14 Q2100, Inc. Method for the production of plastic lenses
US5415816A (en) 1986-01-28 1995-05-16 Q2100, Inc. Method for the production of plastic lenses
US5364256A (en) 1986-01-28 1994-11-15 Ophthalmic Research Group International, Inc. Apparatus for the production of plastic lenses
US6201037B1 (en) 1986-01-28 2001-03-13 Ophthalmic Research Group International, Inc. Plastic lens composition and method for the production thereof
US5008102A (en) * 1986-02-26 1991-04-16 York Kenneth K Biocompatible intraocular light-screening compositions and methods of intraocular light screening
US4863466A (en) * 1986-04-01 1989-09-05 Schlegel Hans Joachim Intra-ocular implant lens
US5041244A (en) * 1986-11-28 1991-08-20 Liquid Sunglasses Corporation Ophthalmic liquid sunglasses
US4765977A (en) * 1986-11-28 1988-08-23 Baron Neville A Ophthalmic liquid sunglasses
US4788007A (en) * 1986-11-28 1988-11-29 Baron Neville A Ophthalmic U.V. absorptive emollient
US4861840A (en) * 1986-12-03 1989-08-29 Barnes-Hind, Inc. Novel siloxanyl acrylic monomer and gas-permeable contact lenses made therefrom
US4872878A (en) * 1987-03-17 1989-10-10 Dennis T. Grendahl Optical brigthener in an intraocular lens
US4872877A (en) * 1987-03-17 1989-10-10 Dennis T. Grendahl Intraocular lens with ultraviolet screening agent
WO1988009663A1 (en) * 1987-06-09 1988-12-15 Mdr Group, Inc. Viscoelastic vitreous substitute with uv blocker
US4853374A (en) * 1987-06-09 1989-08-01 M.D.R. Group, Inc. Viscoelastic vitreous substitute with UV blocker
US4863463A (en) * 1987-12-21 1989-09-05 Tjan Tik T Artificial intra-ocular lens for implantation in the capsular bag
EP0359829A1 (en) * 1988-03-03 1990-03-28 Hoya Corporation Process for producing intraocular lens for correcting cyanopia
EP0359829A4 (en) * 1988-03-03 1991-01-16 Hoya Corporation Process for producing intraocular lens for correcting cyanopia
US5683456A (en) * 1988-10-26 1997-11-04 Pharmacia, Inc. Fabrication of an intraocular lens
US5089180A (en) * 1989-08-31 1992-02-18 Iolab Corporation Method of preparing composite single-piece intraocular lenses with colored haptics
US5037435A (en) * 1990-03-02 1991-08-06 Optical Radiation Corporation Haptics for intraocular lenses having high fracture toughness
FR2696937A1 (en) * 1992-09-04 1994-04-22 Dalloz Sa Christian Intraocular implant for restoration or spectral correction.
EP0589809A1 (en) * 1992-09-04 1994-03-30 Laboratoires Domilens S.A. Intra-ocular implant for spectral restoration or correction
US5514214A (en) 1993-09-20 1996-05-07 Q2100, Inc. Eyeglass lens and mold spin coater
US5480927A (en) * 1994-05-20 1996-01-02 Ciba Geigy Corporation Method of increasing the concentration of radiation-absorbing agents in optical and ophthalmic lenses
US5562734A (en) * 1995-05-31 1996-10-08 Zimmer, Inc. Method for reducing gamma radiation sterilization induced discoloration
US5968094A (en) * 1995-09-18 1999-10-19 Emmetropia, Inc. Compound intraocular lens
US5928575A (en) 1996-04-19 1999-07-27 Q2100, Inc. Methods for eyeglass lens curing using ultraviolet light
US5976423A (en) 1996-04-19 1999-11-02 Q2100, Inc. Methods and apparatus for eyeglass lens curing using ultraviolet light
US6200124B1 (en) 1996-04-19 2001-03-13 Q1200 Apparatus for eyeglass lens curing using ultraviolet light
US6171528B1 (en) 1996-04-19 2001-01-09 Q2100, Inc. Methods and apparatus for eyeglass lens curing using ultraviolet light
US6241505B1 (en) 1996-04-19 2001-06-05 Q2100, Inc. Apparatus for eyeglass lens curing using ultraviolet light
US6174465B1 (en) 1996-04-19 2001-01-16 Q2100, Inc. Methods for eyeglass lens curing using ultaviolet light
US6328445B1 (en) 1996-04-19 2001-12-11 Q2100, Inc. Methods and apparatus for eyeglass lens curing using ultraviolet light
US6022498A (en) 1996-04-19 2000-02-08 Q2100, Inc. Methods for eyeglass lens curing using ultraviolet light
WO1997041806A1 (en) * 1996-05-09 1997-11-13 Prism Ophthalmics Prismatic intraocular lenses and related methods of using such lenses to restore vision in patients with central field loss
US6280171B1 (en) 1996-06-14 2001-08-28 Q2100, Inc. El apparatus for eyeglass lens curing using ultraviolet light
US6244707B1 (en) 1998-07-21 2001-06-12 Wesley Jessen Corporation UV blocking lenses and material containing benzotriazoles and benzophenones
US20090059168A1 (en) * 1999-03-01 2009-03-05 Boston Innovative Optics, Inc. System and method for increasing the depth focus of the human eye
US8752958B2 (en) 1999-03-01 2014-06-17 Boston Innovative Optics, Inc. System and method for increasing the depth of focus of the human eye
US8343215B2 (en) 1999-03-01 2013-01-01 Acufocus, Inc. System and method for increasing the depth of focus of the human eye
US7404637B2 (en) 1999-03-01 2008-07-29 Boston Innovative Optics, Inc. System and method for increasing the depth of focus of the human eye
US7404638B2 (en) 1999-03-01 2008-07-29 Boston Innovative Optics, Inc. System and method for increasing the depth of focus of the human eye
US20060203192A1 (en) * 1999-03-01 2006-09-14 David Miller System and method for increasing the depth of focus of the human eye
US6673888B2 (en) 1999-09-20 2004-01-06 Hoya Corporation Optical materials having good ultraviolet absorbability and method for producing them
US6441119B1 (en) 1999-09-20 2002-08-27 Hoya Corporation Optical materials having good ultraviolet absorbability and method for producing them
US20040141230A1 (en) * 1999-09-20 2004-07-22 Masahisa Kosaka Optical materials having good ultraviolet absorbability and method for producing them
US7009025B2 (en) 1999-09-20 2006-03-07 Hoya Corporation Optical materials having good ultraviolet absorbability and method for producing them
US6448304B1 (en) 1999-09-20 2002-09-10 Hoya Corporation Optical materials having good ultraviolet absorbability and method for producing them
WO2004029675A1 (en) * 2002-09-25 2004-04-08 Medennium, Inc. Method of manufacturing ophthalmic lenses made from hydrophobic acrylic polymers
US20060271177A1 (en) * 2003-05-28 2006-11-30 Christie Bruce A Mask configured to maintain nutrient transport without producing visible diffraction patterns
US20050033420A1 (en) * 2003-05-28 2005-02-10 Bruce A. Christie Mask configured to maintain nutrient transport without producing visible diffraction patterns
US20060271182A1 (en) * 2003-05-28 2006-11-30 Christie Bruce A Mask configured to maintain nutrient transport without producing visible diffraction patterns
US9138142B2 (en) 2003-05-28 2015-09-22 Acufocus, Inc. Masked intraocular devices
US20060271176A1 (en) * 2003-05-28 2006-11-30 Christie Bruce A Mask configured to maintain nutrient transport without producing visible diffraction patterns
US20060271181A1 (en) * 2003-05-28 2006-11-30 Christie Bruce A Mask configured to maintain nutrient transport without producing visible diffraction patterns
US20060271183A1 (en) * 2003-05-28 2006-11-30 Christie Bruce A Mask configured to maintain nutrient transport without producing visible diffraction patterns
US7628810B2 (en) 2003-05-28 2009-12-08 Acufocus, Inc. Mask configured to maintain nutrient transport without producing visible diffraction patterns
US20060079959A1 (en) * 2003-05-28 2006-04-13 Christie Bruce A Mask configured to maintain nutrient transport without producing visible diffraction patterns
US20060268228A1 (en) * 2003-05-28 2006-11-30 Christie Bruce A Mask configured to maintain nutrient transport without producing visible diffraction patterns
US20060271179A1 (en) * 2003-05-28 2006-11-30 Christie Bruce A Mask configured to maintain nutrient transport without producing visible diffraction patterns
US20060271180A1 (en) * 2003-05-28 2006-11-30 Christie Bruce A Mask configured to maintain nutrient transport without producing visible diffraction patterns
US20060268227A1 (en) * 2003-05-28 2006-11-30 Christie Bruce A Mask configured to maintain nutrient transport without producing visible diffraction patterns
US20060274265A1 (en) * 2003-05-28 2006-12-07 Christie Bruce A Mask configured to maintain nutrient transport without producing visible diffraction patterns
US8460374B2 (en) 2003-05-28 2013-06-11 Acufocus, Inc. Mask configured to maintain nutrient transport without producing visible diffraction patterns
US20060079960A1 (en) * 2003-05-28 2006-04-13 Christie Bruce A Mask configured to maintain nutrient transport without producing visible diffraction patterns
US8858624B2 (en) 2003-05-28 2014-10-14 Acufocus, Inc. Method for increasing the depth of focus of a patient
US8864824B2 (en) 2003-06-17 2014-10-21 Acufocus, Inc. Method and apparatus for aligning a mask with the visual axis of an eye
US20070225691A1 (en) * 2003-06-17 2007-09-27 Silvestrini Thomas A Method and apparatus for aligning a mask with the visual axis of an eye
US20060271026A1 (en) * 2003-06-17 2006-11-30 Silvestrini Thomas A Method and apparatus for aligning a mask with the visual axis of an eye
US20060271027A1 (en) * 2003-06-17 2006-11-30 Thomas Silvestrini Method and apparatus for aligning a mask with the visual axis of an eye
US8079706B2 (en) 2003-06-17 2011-12-20 Acufocus, Inc. Method and apparatus for aligning a mask with the visual axis of an eye
US8043371B2 (en) 2003-12-29 2011-10-25 Abbott Medical Optics Inc. Intraocular lenses having a visible light-selective-transmissive-region
US8388681B2 (en) 2003-12-29 2013-03-05 Abbott Medical Optics Inc. Intraocular lenses having a visible light-selective-transmissive-region
US20050143812A1 (en) * 2003-12-29 2005-06-30 Paul Marlene L. Intraocular lenses having a visible light-selective-transmissive-region
US7354980B1 (en) 2004-03-12 2008-04-08 Key Medical Technologies, Inc. High refractive index polymers for ophthalmic applications
US8047650B2 (en) 2004-04-30 2011-11-01 Abbott Medical Optics Inc. Ophthalmic devices having a highly selective violet light transmissive filter and related methods
US20100085534A1 (en) * 2004-04-30 2010-04-08 Abbott Medical Optics Inc. Ophthalmic devices having a highly selective violet light transmissive filter and related methods
US8292428B2 (en) 2004-04-30 2012-10-23 Abbott Medical Optics Inc. Ophthalmic devices having a highly selective violet light transmissive filter and related methods
US8785627B2 (en) 2004-11-22 2014-07-22 Abbott Medical Optics Inc. Copolymerizable methine and anthraquinone compounds and articles containing them
US20080182957A1 (en) * 2004-11-22 2008-07-31 Jason Clay Pearson Copolymerizable azo compounds and articles containing them
US8501890B2 (en) 2004-11-22 2013-08-06 Abbott Medical Optics Inc. Copolymerizable methine and anthraquinone compounds and articles containing them
US8360576B2 (en) 2004-11-22 2013-01-29 Abbott Medical Optics Inc. Copolymerizable methine and anthraquinone compounds and articles containing them
US20090076235A1 (en) * 2004-11-22 2009-03-19 Jason Clay Pearson Copolymerizable methine and anthraquinone compounds and articles containing them
US8188203B2 (en) 2004-11-22 2012-05-29 Abbott Medical Optics Inc. Copolymerizable azo compounds and articles containing them
US9056934B2 (en) 2004-12-07 2015-06-16 Key Medical Technologies, Inc. Nanohybrid polymers for ophthalmic applications
US7446157B2 (en) 2004-12-07 2008-11-04 Key Medical Technologies, Inc. Nanohybrid polymers for ophthalmic applications
US10421830B2 (en) 2004-12-07 2019-09-24 Key Medical Technologies, Inc. Nanohybrid polymers for ophthalmic applications
US20080064840A1 (en) * 2004-12-07 2008-03-13 Khalid Mentak Nanohybrid Polymers for Ophthalmic Applications
US8048972B2 (en) 2004-12-07 2011-11-01 Key Medical Technologies, Inc. Nanohybrid polymers for ophthalmic applications
US20060122349A1 (en) * 2004-12-07 2006-06-08 Key Medical Technologies, Inc. Nanohybrid polymers for ophthalmic applications
US20100261858A1 (en) * 2004-12-07 2010-10-14 Key Medical Technologies, Inc. Nanohybrid polymers for ophthalmic applications
US7745555B2 (en) 2004-12-07 2010-06-29 Key Medical Technologies, Inc. Nanohybrid polymers for ophthalmic applications
US8420753B2 (en) 2004-12-07 2013-04-16 Key Medical Technologies, Inc. Nanohybrid polymers for ophthalmic applications
US7976577B2 (en) 2005-04-14 2011-07-12 Acufocus, Inc. Corneal optic formed of degradation resistant polymer
US20060235514A1 (en) * 2005-04-14 2006-10-19 Silvestrini Thomas A Corneal optic formed of degradation resistant polymer
US8287592B2 (en) 2005-04-14 2012-10-16 Acufocus, Inc. Ophthalmic devices having a degradation resistant polymer
US20060265058A1 (en) * 2005-04-14 2006-11-23 Silvestrini Thomas A Corneal mask formed of degradation resistant polymer and providing reduced corneal deposits
US20110040378A1 (en) * 2007-01-29 2011-02-17 Werblin Research & Development Corp. Intraocular lens system
US20080215147A1 (en) * 2007-01-29 2008-09-04 Werblin Research & Development Corp. Intraocular lens system
US7811320B2 (en) 2007-01-29 2010-10-12 Werblin Research & Development Corp. Intraocular lens system
US8066768B2 (en) 2007-01-29 2011-11-29 Werblin Research & Development Corp. Intraocular lens system
US8066769B2 (en) 2007-01-29 2011-11-29 Werblin Research & Development Corp. Intraocular lens system
US9398949B2 (en) 2007-01-29 2016-07-26 Emmetropia, Inc. Intraocular lens system
US9492272B2 (en) 2009-08-13 2016-11-15 Acufocus, Inc. Masked intraocular implants and lenses
US9005281B2 (en) 2009-08-13 2015-04-14 Acufocus, Inc. Masked intraocular implants and lenses
US20110040376A1 (en) * 2009-08-13 2011-02-17 Acufocus, Inc. Masked intraocular implants and lenses
USD681086S1 (en) 2009-11-10 2013-04-30 Acufocus, Inc. Ocular mask
USD656526S1 (en) 2009-11-10 2012-03-27 Acufocus, Inc. Ocular mask
US9545303B2 (en) 2011-12-02 2017-01-17 Acufocus, Inc. Ocular mask having selective spectral transmission
US9603704B2 (en) 2013-03-13 2017-03-28 Acufocus, Inc. In situ adjustable optical mask
US10350058B2 (en) 2013-03-13 2019-07-16 Acufocus, Inc. In situ adjustable optical mask
US9204962B2 (en) 2013-03-13 2015-12-08 Acufocus, Inc. In situ adjustable optical mask
US10939995B2 (en) 2013-03-13 2021-03-09 Acufocus, Inc. In situ adjustable optical mask
US11771552B2 (en) 2013-03-13 2023-10-03 Acufocus, Inc. In situ adjustable optical mask
US9427922B2 (en) 2013-03-14 2016-08-30 Acufocus, Inc. Process for manufacturing an intraocular lens with an embedded mask

Similar Documents

Publication Publication Date Title
US4636212A (en) Ultraviolet radiation absorbing intraocular lens
US4753654A (en) Ultraviolet radiation absorbing intraocular lens
Glasser et al. A comparison of the efficacy and toxicity of and intraocular pressure response to viscous solutions in the anterior chamber
Bourne et al. The ultrastructure of Descemet's membrane: III. Fuchs' dystrophy
Nadler et al. Glare disability in eyes with intraocular lenses
Apple et al. Complications of cataract and refractive surgery: a clinicopathological documentation
AU653022B2 (en) Procedure for the purification of hyaluronic acid and fraction of pure hyaluronic acid for ophthalmic use
Irvine et al. Retinal damage from the illumination of the operating microscope: an experimental study in pseudophakic monkeys
Ueno et al. Effects of visible-light irradiation on vitreous structure in the presence of a photosensitizer
DE3927667A1 (en) USE OF PHOTOPOLYMERIZABLE MATERIALS AS INTROCULAR LENS FILLING MATERIAL IN THE FIGHT AGAINST CATARACT AND OTHER EYE DISEASES
Liu et al. Biomechanics of sclera crosslinked using genipin in rabbit
Goebbels et al. Endothelial barrier function after phacoemulsification: a comparison between diabetic and non-diabetic patients
Nuzzi et al. Influence of posterior vitreous detachment and type of intraocular lens on lipid peroxidation in the human vitreous
Persad et al. Phototoxicity of chlorpromazine on retinal pigment epithelial cells
Skelnik et al. Neodymium: YAG laser interaction with Alcon IOGEL hydrogel intraocular lenses: an in vitro toxicity assay
DE60109838T2 (en) Eyepiece tissue regeneration inductors
Momenaei et al. Etiology, pathogenesis, and management of acute intraocular lens opacification: a systematic review
Yamauchi Synthetic vitreous body of PVA hydrogel
Argento et al. Study of the lens epithelial cell density in cataractous eyes operated on with extracapsular and intercapsular techniques
Lakomaa et al. Trace element analysis of human cataractous lenses by neutron activation analysis and atomic absorption spectrometry with special reference to pseudo-exfoliation of the lens capsule
JPH0522546B2 (en)
EP0665022A1 (en) Viscoelastic solution of N,O-carboxymethyl chitosan for ophthalmic use
Gurelik et al. Acute corneal decompensation after silicone oil removal
US5385723A (en) Non-primate vitreal replacement process
Legler et al. Comments on silicone intraocular lens discoloration

Legal Events

Date Code Title Description
AS Assignment

Owner name: OPTICAL RADIATION CORPORATION, 1300 OPTICAL DRIVE,

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNORS:POSIN, THOMAS;LAWSON, DANIEL D.;REEL/FRAME:004404/0229

Effective date: 19850416

FEPP Fee payment procedure

Free format text: PAYOR NUMBER ASSIGNED (ORIGINAL EVENT CODE: ASPN); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY

FPAY Fee payment

Year of fee payment: 4

REMI Maintenance fee reminder mailed
LAPS Lapse for failure to pay maintenance fees
FP Lapsed due to failure to pay maintenance fee

Effective date: 19950118

AS Assignment

Owner name: EUROPEAN AMERICAN BANK, NEW YORK

Free format text: SECURITY AGREEMENT/COLLATERAL ASSIGNMENT;ASSIGNORS:OPTICAL RADIATION CORPORATION;OPTICAL RADIATION CORPORATION;REEL/FRAME:008077/0745;SIGNING DATES FROM 19960403 TO 19960719

Owner name: NATIONSBANK, N.A., NORTH CAROLINA

Free format text: SECURITY AGREEMENT/COLLATERAL ASSIGNMENT;ASSIGNORS:OPTICAL RADIATION CORPORATION;OPTICAL RADIATION CORPORATION;REEL/FRAME:008077/0745;SIGNING DATES FROM 19960403 TO 19960719

Owner name: NATIONAL CITY BANK, KENTUCKY, KENTUCKY

Free format text: SECURITY AGREEMENT/COLLATERAL ASSIGNMENT;ASSIGNORS:OPTICAL RADIATION CORPORATION;OPTICAL RADIATION CORPORATION;REEL/FRAME:008077/0745;SIGNING DATES FROM 19960403 TO 19960719

Owner name: NATIONSBANK, N.A., AS AGENT*, NORTH CAROLINA

Free format text: SECURITY AGREEMENT/COLLATERAL ASSIGNMENT;ASSIGNORS:OPTICAL RADIATION CORPORATION;OPTICAL RADIATION CORPORATION;REEL/FRAME:008077/0745;SIGNING DATES FROM 19960403 TO 19960719

STCH Information on status: patent discontinuation

Free format text: PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362

OSZAR »