MXPA96001962A - Method for preparing contact lenses that absorb ultraviol radiation - Google Patents

Abstract

A method for producing a contact lens that absorbs ultraviolet radiation from a polymer in the form of a lens having pendant hydroxyl groups thereof and having an ultraviolet absorbing agent substituted with at least one anhydride group is disclosed therein. is exposed to basic conditions so that the hydroxyl groups react with the anhydride groups on the ultraviolet absorption agent, as a result the ultraviolet absorption agent is fixed to the polymer through the formation of a covalent ester bond

Description

METHOD FOR PREPARING CONTACT LENSES THAT ABSORB ULTRAVIOLET RADIATION BACKGROUND OF THE INVENTION The present invention relates to a method for producing contact lenses that absorb ultraviolet radiation. More particularly, the invention relates to a process for producing hydrophilic contact lenses having an ultraviolet radiation absorbing agent covalently bonded to the polymeric material. It is known that exposure to ultraviolet radiation, 200-U-OOnm, is harmful to the cornea and is the cause of several eye diseases. For this reason it is important to provide adequate eye protection against ultraviolet radiation. Such protection is particularly recommended for people who are prone to ultraviolet exposure, patients who have had cataract surgery and patients with photosensitive drugs. Recently, contact lenses have been developed that serve to absorb ultraviolet radiation, for example, the North American patent IMo. 4,390,676 discloses a contact lens that absorbs ultraviolet light formed by the copolymerization of an appropriate monomer to make lenses and an ultraviolet absorber. The copolymerization efficiency of the compounds has proved inadequate, requiring the extraction of the ultraviolet light absorbing compound before using the lens. The extraction procedure can take from 3 to 20 days. U.S. Patent No. 5,09ñ, t + l + 5 discloses a contact lens that absorbs ultraviolet light having an ultraviolet light absorbing agent covalently bonded to the polymeric material. The ultraviolet absorption agent is applied to the lenses by immersing the lenses in an aqueous medium having dissolved therein a halotriazine which is substituted with an ultraviolet absorption portion. However, it can be expected that the triazinyl molecule that is incorporated therein into the lens polymer will adversely affect the desirable physical and / or refractive properties of the lens. Likewise, depending on whether the halotriazine reacts with the lens polymer introduces uncertainty as to how much reaction occurs, and limits the range of the lens materials in which the ultraviolet absorbers can be incorporated by the techniques described. In fact, this patent teaches that the entanglement of a lens polymer generally renders this technique ineffective, even as it is well known for many contact lenses, especially hydrophilic lenses, it must be made of interlaced polymeric material. There is, therefore, a need for an improved method for producing a contact lens that absorbs ultraviolet light.

There is also a need for a method to produce a contact lens that absorbs ultraviolet light that can be prepared in a relatively short amount of time » There is further a need for a method for producing a contact lens from which the absorption agent has a reduced tendency to leach after preparation 3.c. There is a more particular need for a method for producing a lens by in situ polymerization in which the absorption agent does not interfere with the polymerization reaction.

BRIEF DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a contact lens that absorbs ultraviolet radiation which has an ultraviolet absorption agent covalently bound to the polymeric material. In the present invention, a polymer lens having pendant hydroxyl groups thereof and having an ultraviolet absorbing agent substituted with at least one anhydrous group thereon is exposed to basic conditions such that the hydroxyl groups react with the hydroxyl groups. anhydride groups on the ultraviolet absorption agent. As a result, the ultraviolet absorption agent binds to the polymer through the formation of a "covalent ester bond." Due to the covalent bond, the absorption agent does not leach after lens preparation. the present invention that the ultraviolet absorbing agent at the occlusion level does not interfere with the initiated ultraviolet polymerization of the monomers used in the preparation of the lens.

BRIEF DESCRIPTION OF THE DRAWING Figure 1 is a graph of absorption versus wavelength for a contact lens prepared in accordance with the present invention compared to a conventional contact lens.

DETAILED DESCRIPTION OF THE INVENTION While the present invention is applicable to intraocular lenses and lenses used in spectacles, it will be described in relation to contact lenses, both corrective and non-corrective. The present invention relates to a method for producing ultraviolet radiation absorbing lenses comprising an ultraviolet absorption agent covalently bonded to a polymeric lens material. The ultraviolet absorption agent is an ultraviolet absorption compound 5 substituted with at least one anhydrous group. It is through the anhydrous group that the ultraviolet absorption agent is capable of covalently bonding to the pendant hydroxyl groups of the polymer. The ultraviolet absorption compound is selected from the group of radiation-absorbing compounds that contain wavelengths within all or part of the 200-4-50 nm scale and have functionality that allows binding to an anhydrous group. The ultraviolet absorption compounds include oxalic acid diamides, hydroxyphenyltriazines, benzotriazoles, benzophenols, benzoic acid esters and cyano and carbomethoxy acylates. Examples of oxalic acid diamides include, 4,4'dioctylaxyoxanuide, 2,2'-diioktoxyl-5, 5'-di-ter "butyloxanilide, 2,2'-didodecyloxy-5, 5'-di -ter-bu-iloxanilide, 2-ethoxy-2'-etiloxanilide, N, N'-bis (3-ethyloxanilide and their mixtures with 2-ethoxy-2'-et il-5,4'-di-tert- builoxanilide and mixtures of ortho- and para-methoxy disulbstituted oxanilides and mixtures of o- and p-ethoxy-disubstutan oxanilides Examples of hydroxy-phen-iazines include 2- (2-hydroxyphenyl) -l, 3, 5-triazines such as 2,4,6-tris < 2-h idraxi- 4- ct i lox i phenyl) -i, 3, 5-t. Iazine, 2- (2-hydra i-4-octi loxifeni 1) -, -bi s- 2, 4-d imethylphenyl) -l, 3, 5-triazine, 2- (2-, 4- dihydroxyphenyl) -4, -bis (2, 4-d imet i lfeni 1-1, 3, 5-triazine, 2,4-bis (2-hydroxy-4-propyl and phenyl) -6- (2, 4-di et i lfeni 1) -l, 3, 5- triazine, 2- <2-h idrox i-4-oct i lox i fen i 1) -4, -b is (4-meth i 1 phen i 1- 1, 3, 5- riazine, 2- (2 -hydroxy-4-doceci loxif ni 1) -4,6-bis < 2,4-di etilfeni 1-1, 3 , 5-tri zina. Benzotriazoles include 5'-ethyl, 3 ', 5'-di-tert-butyl, S'-tert-butyl 5' - (1, 1, 3, 3-tetramet and Ibut i 1), 5- chloro-3'-5'-di-tert-butyl, 5-chloro-3'-ter-but i 1-5 '-met i 1, 3'-sec-but-il-5'-ter'-butyl , 4'-octoxy, 3 '5'-di-ter-ami lo and 3', 5'-bis ("," -dimet ilbenzyl) derivative of 2- (2'-hydroxyphenyl) -benzotriazole Examples of benzophenones they include 4-hydroxy, 4-methoxy, 4-octoxy, 4-decyl, 4-dodecyl, 4-benyl, 4,4'4'-t-hydroxy and 2'-hydroxy-4,4'- Dimethoxy and 2-Hydroxybenzophenone Derivatives Examples of substituted and unsubstituted benzoic acid esters include 4-tert-butyl-ylphenyl salicylate, phenyl salicylate, octylphenyl salicylate, dibenzoylrescorinol, bis (4-tert -buylbenzoyl) -resor , benzoylrescorinol, 4-hydroxybenzoate 2,4-di-tert-butyl-phenyl-3,5-di-tert-butyl and hexadecyl-3-hydroxybenzoate 3,5-di-ter- • buyl Examples of acrylates include β -cyano-ß ~ ß-diphenylacrylate ethyl, «-cyciano- -ß-diphenylacrylate methyl '-carboyl methanolamine methyl' -cyano-ß-met il-p-methoxy-cinnamate methyl, butyl, ac iano-ß-met i lo-p-methoxy-methyl carbamate and «-carbometoxy-p -methoxycinanamate and N- (ß-carbometho i-ß-c ianovin i 1) -2-met ilindoline. These ultraviolet absorption compounds are commercially available or can be synthesized by conventional techniques known to someone with experience in the tea. The ultraviolet absorption agent used in the process of the present invention is an ultraviolet absorption compound substituted with minus an anhydrous group. The preferred ultraviolet absorbing agent is benzophenone tetrabenzoic acid dihydrogen. The ultraviolet absorption agent is prepared by derivatizing the ultraviolet absorption compounds described herein to assist the anhydride group (s). This synthesis can be carried out using known techniques. Common synthesis techniques include using thionyl chloride to activate a carboxylic acid by forming the corresponding acryloyl chloride which reacts with the free carboxylic acid; the activation of the carboxylic acid with phosphoric acid halides, for example (PhC ^ POCl), the use of carbodimides to effect the dehydration of the carboxylic acid to anhydrides, and the use of dehydration agents such as trimethylsilylethoxyacetylene (MeS3Si-C- = C-0E) A well known method for providing non-symmetrical anhydrides involves reacting metal salts of carboxylic acids with acid halides The amount of aggregated ultraviolet absorption agent is determined empirically as each agent absorbs & differently and since each would have a different level at which it could be incorporated into the lens before it interfered with the polymerization. Where the ultraviolet absorption agent is incorporated into the mixture of monomers that are subsequently polymerized to form the lens, it is critical that the ultraviolet absorption agent at the inclusion level does not interfere with the ultraviolet initiated polymerization of the monomers used to make the lens contact; in such embodiments of the invention, a sufficient amount is selected to increase the ultraviolet absorption capacity without interfering with the polymerization. In general, satisfactory amounts of anhydride derivative-ultraviolet absorption agent that are used when added to the monomer mixture are in the order of 0.5 to 4.0% and satisfactory amounts when infiltrated into the lens after polymerization are present. in the order of 0.5 to 5.0%. Those scales will vary depending on aspects such as the reaction efficiency of the ultraviolet-anhydrous derivative agent, the final hydrated lens thickness and the dispersion of the ultraviolet absorbing agent within the lens. The compounds that form the material of the polymeric lens can vary as long as a component is present in the monomer mixture which in accordance with the polymerization will provide the polymer with the desired hydroxyl groups required. Examples of such monomers include, but are not limited to, hydroalkylamino, hydroxyalcnxyalkyl, hydroxy (polyalkoxy) esters, and poly (alkoxy) esters of polymerizable unsaturated acids, such as acrylic acid, methacrylic acid, fumaric acid, etc. Other suitable monomers include unsaturated acids per se, such as acrylic, methacrylic, fumaric, maleic, etc .; Heterocyclic N-vinyl lactams, such as N-vinyl pyrrolidone, etc .; noncyclic amides such as N- (1,1-dimethyl-3-oxobutyl) -acrylamide; esters amino alkyls of unsaturated acids such as 2-aminoet i lacrylate, methacrylate, fumarate, or maieate; mercaptoalkyl ethers of unsaturated acids such as acrylate, methacrylate, fumarate or 2-me.rcaptoetyl maieate. Other suitable monomers, particularly wherein each alkyl group contains 1 to 3 carbon atoms will be apparent to one skilled in the art. It is preferable to use hydrophilic monomers, ie monomers in appropriate amounts, so that the polymerized product is hydrophilic. A hydrophilic polymer is a ca.pa.z polymer capable of forming a hydrogel when contacted with water. It is more preferable for this reason to use hydroxy-substituted hydroxy monomers. The most preferred hydrophilic monomers are esters of acrylic or methacrylic acid with alkyl groups (especially containing 1 to 6 carbon atoms) which are substituted with 1, 2 or more hydroxyl groups. Examples of such hydroxy ethers include, but are not limited to, hydroxyethyl methacrylate, (HEMA), hydroxyethyl methacrylate, (HEA), 2,3-dihydroxypropyl methacrylate (glyceryl ethacrylate), hydroxypropylmethacrylate and hydropropyl ilacri late. . The most preferred hydroxy ester is HEMA, which is the monomer most commonly used in the preparation of "soft" hydrogel contact lenses. HEMA is described in U.S. Patent No. 2,976,576 and U.S. Patent No. Re 27,401. An acceptable "hard" lens material is cellulose acetate-butyrate. Other suitable monomers containing reactive hydrogen, such as the OH or NH groups, will be apparent to those skilled in the art. The hydrophilic monomer is preferably copolymerized in a reaction mixture or hydrophilic or hydrophobic comonomers such as methacrylic acid (MAA). In addition, the polyfunctional monomers, used as crosslinking agents, such as ethylene glycol dimethacrylate (EGDMA) and trimethoprimethate trimethacrylate (TMPTMA), can be used to improve dimensional stability and other physical lens properties. Additional comonomers and entangle comonomers include acrylate diesters and polyethylene glycol methacrylate (IPEG) wherein the molecular weight of the PEG segment is from 100 to 6,000, the diesters of acrylate and methacrylate of bisphenol A (BPA) diols ethoxylated in one or in each one of the diol ends with 1-20 ethoxy units, aliphatic alcohol acrylates C ^ -C ^ and methacrylates, methacrylates of Cj: -C? alcohol-perfluoro and alcohol acrylates C ^ -CLÍ, perf luoro. By "acrylate and methacrylate diesters" = e denotes diacrylates, dimethacrylates, and diesters bearing an acrylate moiety and a methacrylate moiety. Examples include PEG 4500, BPA (ethoxylated with a total of 10 moles of ethylene oxide (EO)), PEG 350 monomethyl ether or dodecapol, which have been reacted with 1 or more molar equivalents of a blocking group at the end such as methacrylate methacrylate (IEM), methacrylic anhydride or methacrylic chloride to produce compounds with one or more terminal methacrylate groups linked through linking portions such as carbamate or ester groups. Other comonomers and entangle comonomers are well known to someone of normal experience. The man-made reaction mixture also includes an initiator, usually from about 0.05 to 5.0 percent of a free radical initiator that is thermally activated. Typical examples include lauroyl peroxide, benzoyl peroxide, isopropyl percarbonate, azobisisobutyronitrile and known oxide reduction systems such as the combination of ammonium persulfate-metabisulfite sodium and the like. Irradiation by ultraviolet light, electron beam, or other radioactive source can also be used to initiate the polymerization reaction, optionally with the addition of a polymerization initiator, for example benzoin and its ethers. It is preferred to use "-hydroxy-", a-d imet i lacetophenone (Darocur 1173) which is a reactive ultraviolet initiator. Other initiating compounds would be familiar to someone of experience perm..I. The polymerization reaction is known for those of ordinary skill in the art carried out under conditions that can be readily established for a particular set of reagents. The polymerization can be carried out in the presence or absence of an inert diluent. If the polymerization is carried out in the absence of a diluent, the resulting polymer composition can be formed, such as by lathe cutting, into the desired lens shape. Alternatively, more preferably, the polymerization is carried out in the presence of an appropriate inert diluent, for example, the diluents described in the US Pat. 4,6β0,336 which is incorporated herein by reference. The polymerization can also be carried out in the presence of an inert diluent displaceable with appropriate water, for example the diluents such as methanol, ethanol, acetone, and glycol, described in EPO Application No. 94305394.2 which is incorporated herein by reference. The preferred inert diluent is a boric acid ester displaceable with water. The characteristics of the desired boric acid esters as well as the preferred concentration of the ester in the polymerization reaction mixture is described in detail in U.S. Patent No. 4,495,313 which is incorporated herein by reference. For example, suitable boric acid esters include those prepared by heating boric acid and one or more polyhydroxyl compounds with three or more hydroxyl groups. Suitable polyhydroxyl groups include glycerol, trimethylolpropane, glucose, and mixtures of any of those compounds having two hydroxyl groups such as propylene glycol, diethylene glycol, butanediol, and / or sorbitol. Preferred methods for forming the desired lens when a diluent is used include centrifugal casting and casting, for example using the molds described in U.S. Patent No. 4,565,346, as well as combinations of those methods with the other methods generally described herein. The ultraviolet absorption agent (i.e., one or more ultraviolet absorption compounds substituted with at least one anhydrous group) must be dispersed through the polymer prior to the covalent bonding of the agent with the polymer structure. This can happen in one of two ways. One way is to add the ultraviolet absorption agent to the mixture of monomers and the other materials used to form the lens. The reaction mixture undergoes polymerization under conditions such that the ultraviolet absorption agent does not react. The resulting polymer contains the ultraviolet absorption agent dispersed therethrough. The second way to disperse the agent through the polymer is to impregnate the already formed polymer into a solution, preferably an aqueous solution, which contains the ultraviolet absorption agent. The solvent, if not water, must be capable of transporting the ultra-violet absorber in and through the lens polymer, without reacting with the anhydrous group or groups, the ultraviolet absorption compound, or the polymer. Other solvents include methanol, ethanol and isopropyl alcohol. By this method, a preformed contact lens is placed in a solution containing an ultraviolet absorption agent. The polymer, with the ultraviolet absorption agent dispersed therethrough is then reacted to cause it to support a base hydration to covalently bind the agent to the polymer through the pendant hydroxyl groups of the polymer. This can be done using the conventional technique of contacting the lenses with an aqueous solution of a base such as sodium hydroxide or potassium hydroxide before hydration as described, for example, in U.S. Patent No. 4,691,046 which is incorporated herein by reference. The preferred base is an alkaline or alkaline earth metal carbonate, or phosphate, and the required contact time will depend on the contact temperature and the components of the hydrophilic polymer composition. When the bond of the ultraviolet absorption agent to the polymer is complete, the lens can be hydrated to its water content equilibrium. Generally, the water content of the lens will vary from approximately 0 to approximately 100%.5 by weight, preferably 30 to 60% by weight. It is intended that the following examples illustrate the claimed invention and are in no way designed to limit its scope. Numerous additional embodiments within the scope and spirit of the claimed invention will become apparent to those skilled in the art. The components used in the preparation of the contact lenses of the examples are reissued as follows; 0 2-hydroxyethyl methacrylate (HEMA), methacrylic acid (MAA), ethylene glycol d methacrylate (EDGMA), trime thiolpropane tri-acrylate (TMPTMA), glycerin-boric acid ester (BAE) and a-hydroxy- «,« -dimethylacetophenone (Darocur 1173), which is a reactive ultraviolet initiator. The mon? used in all the examples are highly purified monomers with less than 0.1% impurities. Photonol 7025 is a polyetherdiol used as a scrubbing diluent with inert water and available from Henkel Corporation in Ambler, Pennsylvania. 0 Example 1 Synthesis of the ester of glycerin-boric acid (BAE). A total of 61.63g (1.0 mis) of boric acid is placed in a 3-liter rotary evaporator flask. To this 5 flask is added 322.32 g of glycerin (3.5 mols). The flask is then placed on a rotary evaporator and the pressure is allowed to slowly reduce to 0.5-1.0 mm Hg. After the total vacuum has been established, the temperature of the bath rises slowly to 65 ° C to about 5 ° C for every 20 minutes. The water is recovered from the reaction as the boric acid ester is formed. The clear viscous liquid BAE was used as such.

Example 2 Preparation of the monomer reaction mixture with BAE. A mixture was prepared using 96.61% by weight of HEMA, 1.97% MAA, 0.76% EGDMA, 0.1% TMPTMA of 0.34% of DAR0CUR 1173. To 46% by weight of this monomer mixture 52% of BAE was added as a diluent displaceable with inert water. After thoroughly mixing the resulting formulation (hereinafter "reactive monomer mixtures" or "RMM") under ambient conditions, the mixture was allowed to stir under reduced pressure (40 mm Hg) for 30 min (at 25 ° C) and subsequently it was transferred to contact lens molds. The filled molds were exposed to UV light (wavelength = 300-360 nm, dose = 1.2-1.6 Jolules / c 2) for 20 minutes at about 50 ° C. The molds were then separated, and placed in physiological saline for 3.0 hrs at 70 ° C to remove the inert diluent and any residual unreacted monomers. The lenses were then washed in fresh physiological saline solution at 40 ° C. After the initial hydration period the lenses were allowed to equilibrate in a fresh bath of physiological saline solution at 35 ° C for 3 hours. Examples 3-β Solubility of the ultraviolet Absorption agent. To separate the samples of the reactive monomer mixture (RMM) prepared according to example 2, 0.05, 0.10, 0.25, 0.60, 0.60 and 1.0% of benzofenointetracarboxy 1 ian dianhydride were added. After thoroughly mixing each sample under ambient conditions, the mixtures were allowed to stir under reduced pressure (40 mm Hg) for 30 min at 25 ° C. The mixtures were then used to determine the solubility of the anhydrous ultraviolet absorption agent in the polymer and the effect of the anhydrous ultraviolet absorption agent on the polymerization reaction as = e? monitoring through DSC ie TTP and enthalpy.

Example 9 Preparation of the photonol 7025 monomer reaction mixture as an inert, water-displaceable diluent. A mixture was prepared using 96.61% by weight of HEMA, 1.97% MAA, 0.76% EGDMA, 0.1% TMPTMA and 0.34% of DAR0CUR 1173. To 46% by weight of this monomer mixture ee added 52% of Photonol 7025. After thoroughly mixing the resulting formulation (hereinafter the "reactive monomer mixture" or the "RMM"> under ambient conditions) the mixture was allowed to stir under reduced pressure (40 mm Hg) for 30 minutes at 25 ° C. C.

Example 10 To a sample, 99.0%, of the reactive monomer mixture (RMM) of Example 9 were added 1.0% dianhydro 3, 3 ', 4,4'-benzophenonetetracarboxy 1 ico. After completely mixing the fore-moletra under ambient conditions the mixture was allowed to stir under reduced pressure (40 mm Hg) for 30 minutes at 25 ° C. This mixture was then used to determine the solubility of the anhydrous ultraviolet absorption agent in the polymer and the effect of the ultraviolet absorption anhydride on the polymerization reaction as monitored by DSC ie TTP and enthalpy.

E. Example 11 Preparation of contact lenses with ultraviolet absorption agent. To a sample, 99.2%, of the reactive monomer mixture (RMM) of Example 9 was added 0.6% dianhydro 3,3 ', 4,4'-benzophenonetetracarboxylic acid. After thoroughly mixing the above sample under ambient conditions the mixture was allowed to stir under reduced pressure (40 mm Hg) for 30 minutes (at 25 ° C) and subsequently transferred to contact lens molds. The filled molds were exposed to UV light (wavelength = 300-360 nm, dose = 1.2-1.6 Jolulee / cm52) for 30 minutes at approximately 50 ° C. The molds were then separated, and placed in physiological saline for 3.0 hrs at 70 ° C to remove the inert diluent and any residual unreacted monomers. Then, the lenses were hydrated in a 2% by weight aqueous solution of potassium carbonate at 50 ° C for 60 minutes. After this initial hydration period the lenses were washed in fresh physiological saline at 50 ° C for 15 minutes. The lenses were left to equilibrate in fresh fieiological exit solution at 35 ° C for 3 hours, from where they were ready for packaging. The test methods for determining physical properties are set out in Tables I, II and III as follows: FOTQ DIFFERENTIAL SCREENING CALCULATOR A sample with a size of 5.0 milligrams was used. Nitrogen was purged at 40 mL / min and temperature of 45 ° C isothermal. The healing cycle started at 10 minutes at an intensity of 2.5mW / cm: a and continued for 10 minutes. The polymer "Acuvue 10.4" cured under the same conditions was used as the reference material.

TABLE I TABLE II TABLE III The results shown in Table I (BAE as diluyeptes) and Tables II and III (Photonsl 70259 as diluents) indicate that the polymerization was not adversely interfered with the inclusion of ultraviolet absorption species. It is critical that the ultraviolet absorption material at the inclusion level does not interfere with the ultraviolet initiated polymerization of the monomers used to prepare the hydrogel. The results of time to peak (TTP) and enthalpy (E) were obtained using a differential scintillation photocalorimeter. The TTP is the point at which the maximum heat of the reaction occurs and is the point after which the reaction velocity decreases.

UV-VIS SPECTROSCOPY Three separate samples prepared according to Example 11 were analyzed using a Cary Model 2300 UV-Vie spectrometer with a scanning speed of 1 nm / sec, pre-Inm solution and scanning scale of? 600-200nm. A lens held within a lens holder with a 6 mm aperture was inserted into a quartz tube filled with physiological saline. The previous correction was made with a quartz tube, lens holder and physiological saline solution without the lens. The control was "Acuvue" prepared according to example 2. The results in figure 1 show the increased ultraviolet absorption ability of the samples containing the ultraviolet absorption agent compared to a lens that does not have it. The test methods to determine the physical properties are established in Table IV eon as follows: TENSION PROPERTIES (MODULE, EXTENSION AND RESISTANCE) A sample prepared in accordance with Example 11 was cut to the desired sample size and shape, and the cross-sectional area was measured. The sample was then fixed to the top-grip of a constant velocity crossover type test instrument equipped with a load cell. The sample was elongated at a constant speed of effort and the resulting stress-strain curve was recorded. The results are shown in table IV; the elongation is expressed in percentage, and the tension and resistance module in kg / cm53.

CONTENT GR VIMETRICO DE AGUA The water content in a lens prepared according to example 11 was determined by first weighing a lens that has been equilibrated in saline, and subsequently drying the lens for 2 hours at 65 ° C under reduced pressure (<5 mm Hg). . The dried lens was weighed and the gravimetric water content was calculated as follows: % water = lOO X < mweB.t - mdry) / mwa »t where mwrat represents the wet lens mass (mass of the polymer plus the mass of saline) and mdry represents the dry polymer mass. VISCOSITY Viscosity was measured using a Brookfield Digital Model DV-II viscometer, Brookfield Engineering Laboratories, Inc. A mixture prepared in accordance with Example 11 was equilibrated to + 0.5 ° C in the viscometer fluid container using a Fisher Scientific refrigerant circulator (Model 9100 series) and monitored with an Omega microprocessor thermometer (Model HH23). The direct reading obtained from the viscometer was multiplied by the appropriate factor for the spindle and speed used and expressed in centipoise. The mixtures that use PEG 2000 have a screw 16 and speed of 6 rpm; the mixtures used by PEG 4500 have a spindle of 16 and a speed of 3 rpm.

WATER CONTENT The water content was measured using Coula atic -F Tritrimeter Model 447, Fieher Scientific. A mixture prepared according to example 11, was injected inside 2 of the reaction vessel using a 1 c syringe. The weight of the sample was 0.4-0.6 grams, with an extraction time of 20 seconds. Direct reading of the content of- Water was expressed as a percentage by weight.

TABLE VI

Claims (2)

1. NOVELTY OF THE INVENTION CLAIMS 1. - A method for producing a contact lens with absorption absorbing ultraviolet light characterized because it comprises the steps of; (a) providing a polymer in the form of a lens having pendant hydroxyl groups thereof and having dispersed therein an ultraviolet absorbing agent substituted with at least one anhydrous group; and (b) exposing said polymer to the basic conditions effective to cause said hydroxyl groups to react with the anhydride groups on said ultraviolet absorption agent, wherein said ultraviolet absorption agent is covalently bound to the polymer.
2. 2. A method according to claim 1, further characterized in that the step a comprises providing a homogeneous monomer solution comprising therein one or more polymerizable monomers that include at least one substi tuted polymerizable hydroxyl monomer, wherein said solution contains dispersed therein said ultraviolet absorption agent, under conditions effective to polymerize said one or more polymerizable monomers without causing said ultraviolet absorption agent to react. 3. - A method according to claim 1, further characterized in that said step (a) comprises providing a polymer in the form of lenses having pendant hydroxyl groups thereof, and contacting the polymer with a solution of said low ultraviolet absorption agent effective conditions for causing said ultraviolet absorption agent to impregnate itself within said polymer. 4. A process according to claim 1, further characterized in that said ultraviolet absorption agent is 3,3 ', 4,4'-benzophenonetetracarboyl dianhydride. 5. A process according to claim 1, further characterized in that said ultraviolet absorption agent is an anhydride derivative of dioctyloxyoxanilide, 2,4,6-tris (2-hydroxy-4-octyloxy phenyl) -1, 3, 5-triazine, 4-tert-but-ylphen-ilsalicylate, dibenzoyl-resorcinol, or 3'-sec-butyl-5'-tert-butyl-2- (2'-hydroxyfen i.Dbenzotriazal) 6.- A compliance procedure 7.- A method according to claim 2, further characterized in that said monomer solution comprises hydroxyalkyl methacrylic acid 7.- A method according to claim 2, further characterized in that said monomer solution comprises hydroxyethylmethacrylate. . 6. - A method according to claim 2, further characterized in that said monomer solution comprises one or more compounds selected from the group consisting of hydroxyethyl, lacrylate, 2,3-dihydroxypropylmethacrylate, hydroxypropylmethacrylate and hydroxypropylurea. . 9 »- A method according to claim 2, further characterized in that said solution of? Onomer comprises hydroxyethyl methacrylate and methacrylic acid. 10. A method according to claim 2, further characterized in that said solution of? The monomer comprises hydroxyethylmethacrylate and methacrylic acid and ethylene glycol dimethacrylate 11. A process according to claim 2, further characterized in that said monomer solution comprises hydroxyethyl methacrylate, ethacrylic acid, ethylene glycol dimethacrylate, and Trimethacrylate trimethylolpropane 12. A process according to claim 2, further characterized in that said monomer solution comprises "-hydroxy-", -dimet and lacetophenone 13.- A method according to claim 2, characterized in addition, because the polymer is formed by the copolymerization of a monomer mixture comprising one or more hydroalkyl esters of acrylic or methacrylic acid. 14. - A method according to claim 2, further characterized in that the polymer is formed by the copolymerization of a monomer mixture comprising hydroxyethyl methacrylate. 15. A method according to claim 3, further characterized in that the polymer is formed by the copolymerization of a monomer mixture comprising hydroxyethyl acrylate, 2,3-dihydroxypropyl methacrylate, hydroxypropyl methacrylate, and hydroxypropyl methacrylate. 16. A process according to claim 3, further characterized in that the polymer is formed by the copolymerization of a monomer mixture comprising hydroxyethyl methacrylate and methacrylic acid. 17. A process according to claim 3, further characterized in that the polymer is formed by the copolymerization of a monomer mixture comprising hydro? Ethyl methacrylate, methacrylic acid and ethylene glycol dimethacrylate. 16. A process according to claim 3, further characterized in that the polymer is formed by the copolymerization of a monomer mixture comprising hydroxyethylmethacrylate, methacrylic acid, ethylene glycol dimethacrylate and trimethylolpropane trimethacrylate. 19. A process according to claim 3, further characterized in that the polymer is formed by the copolymerization of a mixture of onomer comprising "-hydro? I-", a-d imeti lacetophenon. 20. A process according to claim 2, further characterized in that the monomer solution includes a diluent displaceable with water. 21. A process according to claim 2, further characterized in that said monomer solution includes boric acid ester. 22. - A method according to claim 2, further characterized in that said monomer solution comprises one or more compounds selected from the group consisting of polyethylene glycol acrylate and methacrylate diéteres in which the molecular weight of polyethylene glycol is 100 to 6,000, the diesters of acrylate and methacrylate of bisphenol A diols ethoxylated in one or each of the diol ends with one to 20 ethoxy units, aliphatic alcohol acrylates of 0 ^ -0 ^ and methacrylates, methacrylates of alcohol C? ~ CA, perfluoro and alcohol acrylates perf luoro. 23. A method according to claim 2, further characterized in that said monomer solution comprises one or more compounds selected from the group consisting of PEG 4500, bisphenol A diolsi ethoxylates with a total of 10 moles of ethylene, onome il ether, and dodecanol, whose compounds have been blocked at the end with isocyanate ethyl methacrylate, "methacrylic anhydride or methacrylic boride. 24. A method according to claim 3, further characterized in that said solution of? The monomer includes an inert diluent displaceable with water. 25. A method according to claim 3, characterized in that said solution of? monomer includes an ester of boric acid. 26. A process according to claim 3, further characterized in that said monomer solution comprises one or more compounds selected from the group consisting of diesters of acrylate and polyethylene glycol methacrylate wherein the molecular weight of the polyethylene glycol is 100 to 6,000, the esters of acrylate and methacrylate of bisphenol A diols etholated at one or each end diol with 1 to 20 ethoxy units, acrylates and aliphatic alcohol methacrylates dC? alcohol methacrylates Cx-C¿. perfluoro and alcohol acrylates Cx ~ C? perfluoro. 27. A method according to claim 3, further characterized in that the monomer solution comprises one or more compounds selected from the group consisting of PEG 4500, bisphenol A diols, ethoxylated with a total of 10 moles of ethylene oxide , monomethyl ether, PEG 350 and dodecanol, and the compounds have been blocked at the end with ethyl isocyanate methacrylate, methacrylic anhydride or methacrylic chloride. METHOD FOR PREPARING CONTACT LENSES THAT ABSORB ULTRAVIOLET RADIATION SUMMARY OF THE INVENTION A method for producing a contact lens that absorbs ultraviolet radiation from a polymer in the form of a lens having pendant hydroxyl groups thereof and having an ultraviolet absorbing agent substituted with at least one anhydride group is disclosed therein. Are you exposed to basic conditions so that? the hydroxyl groups react cc.i the anhydride groups on the ultraviolet absorption agent; as a result the ultraviolet absorption agent binds to the polymer to formation of a covalent ester linkage. RM / mvs * cgt * ieah *