MXPA00010751A - Plasma surface treatment of silicone hydrogel contact lenses - Google Patents

Abstract

The present invention provides an optically clear, hydrophilic coating upon the surface of a silicone hydrogel lens by subjecting the surface of the lens to a process comprising plasma treatment, hydration, and heat sterilization that is controlledto result in a silicate-containing film having a mosaic pattern of projecting plates surrounded by fissures when viewing a 50x50 micron square AFM image, wherein the peak-to-valley distances of the fissures are on average between about 100 and 500 angströms and the plate coverage is on average between about 40%to 99%.

Description

SUPERFICIAL TREATMENT WITH PLASMA OF SILICONE HIDROGEL CONTACT LENSES FIELD OF THE INVENTION The present invention relates to the surface treatment of silicone hydrogel contact lenses. In particular, the present invention relates to a method of modifying the surface of a contact lens to increase its wettability and to decrease its susceptibility to depopulation of proteins and lipids during use. The surface treatment results in a surface film or silicate-containing coating having a mosaic configuration of raised plates surrounded by receding spaces or cracks. When viewing an AFM image of 50x50 microns square of the surface, the peak to valley distances of the fissures are on average between approximately 100 and 500 angstrems and the plaque coverage is on average between approximately 40% and 99% BACKGROUND Contact lenses made of silicone-containing materials have been investigated for several years. Such mate- Riales can be subdivided in general into two main classes, namely hydrogels and not hydrogels. The non-hydrogels do not absorb appreciable amounts of water, while the hydrogels can absorb and retain water in a state of equilibrium. Regardless of their water content, both non-hydrogel and hydrogel silicone contact lenses tend to have relatively hydrophobic non-wettable surfaces. Those skilled in the art have long recognized the need to modify the surface of such silicone contact lenses so that they are compatible with the o] o. It is known that increasing the hydrophilicity of the surface of the contact lens improves the wettability of contact lenses. This in turn is associated with greater comfort in the use of contact lenses. In addition, the surface of the lens can affect the susceptibility of the lens to deposition, in particular the deposition of proteins and lipids from the tear fluid during the use of the lens. Accumulated deposition can cause discomfort in the eye or even inflammation. In the case of long-wearing lenses, the surface is especially important, since prolonged use of the lens must be designed for high tiáÜj ^ tt ^; comfort levels over a long period of time, without specifying the daily removal of the lens before sleep. Thus, the regime of use of long-wearing lenses would provide a daily period of time for the eye to recover from any discomfort or other possible adverse effects of the use of the lens. Silicone lenses have been subjected to surface treatment with plasma to improve their surface properties, for example, the surfaces have become more hydrophilic, resistant to deposits, resistant to scratching, or otherwise modified. Examples of plasma surface treatments described above include subjecting the surfaces of the contact lens to a plasma that includes an inert gas or oxygen (see, e.g., U.S. Patent Nos. 4,055,378; 4,122,942; and 4,214. .014); various hydrocarbon monomers (see, for example, U.S. Patent No. 4,143,949); and combinations of oxidizing agents and hydrocarbons such as water and ethanol (see, for example, WO 95/04609 and U.S. Patent No. 4,632,844). U.S. Patent No. 4,312,575 issued to Peyman et al. Describes a process for obtaining a barrier coating on a silicone or polyurethane lens. rt ^ _____ »___________ This is done by subjecting the lens to an electric luminescent discharge (plasma) process performed by first subjecting the lens to a hydrocarbon atmosphere followed by subjecting the lens to oxygen during flow discharge, thereby increasing the hydrophilicity of the lens surface. Although such surface treatments have been described to modify the surface properties of silicone contact lenses, the results have been problematic and of questionable commercial viability, which undoubtedly has contributed to the fact that the contact lens of silicone hydrogel still has to be marketed. For example, U.S. Patent No. 5,080,924 to Kamel et al. States that, although it is known to expose the surface of an object to plasma discharge with oxygen to improve the wettability or hydrophilicity of such a surface, such treatment is only temporary. Although the prior art has attempted to show that it is possible to perform the surface treatment of contact lenses in the non-hydrated state, there has been little or no discussion of the possible effect of the following treatment or manufacturing steps in the surface treatment of the lens and The surface properties of a product have not been exposed or described. fully processed hydrogel lens manufactured for real use. Likewise, little or no information has been published. Thus, it is desired to provide a silicone hydrogel contact lens with an optically clear hydrophilic surface film which will not only exhibit better wettability, but will generally allow the use of a silicone hydrogel contact lens in the human eye over a period of time. extended time. In the case of a silicone hydrogel lens for prolonged use, it would be highly desirable to provide a contact lens with a surface that is also highly permeable to oxygen and water. Such a treated surface lens would be comfortable to wear in actual use and would allow prolonged use of the lens without irritation or other adverse effects to the cornea. It would be desirable if such a treated surface lens were a commercially viable product capable of economic manufacture.

COMPENDIUM OF THE INVENTION The present invention relates to a silicone hydrogel lens with a silicate-containing surface film having a configuration of rust-like plaque surrounded by receding spaces or cracks upon viewing a ____________ ^^^^ AFM image (atomic force microscopy) of 50x50 square micras in which the average distance from peak to valley (or average depth) of the fissures is between approximately 100 and 500 angstroms and the plaque coverage is on average approximately 40% 99% The present invention also relates to a method of modifying the surface of a contact lens to increase its wettability and to increase its resistance to deposit formation during use. The surface film can be made by oxidative treatment with plasma of the lens under suitable conditions of plasma followed by hydration and sterilization in autoclave.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a flow chart of a manufacturing process for making a lens having a lens coating according to the present invention. Figure 2 is a topographic image by atomic force microscopy (AFM) (50x50 microns) showing a plasma-treated lens before further processing by extraction, hydration and sterilization according to the present invention. Figure 3 is a topographic image by microscopy of atomic force (AFM) (50x50 square microns) showing, for comparison, a lens treated with hydrated plasma and sterilized in autoclave (completely processed) after a period of time of only 4 minutes, otherwise processed in a comparative manner with the lens in Figure 3, which shows a relatively smooth surface with barely visible plates and approximately 20 percent surface coverage. Figure 4 is a topographic image by atomic force microscopy (AFM) (50x50 microns) showing a plasma-treated lens according to the present invention that has been extracted with isopropanol and before autoclaving, which presents approximately 50 percent of superficial coverage. Figure 5 is a topographic image by atomic force microscopy (AFM) (50x50 microns) showing a lens treated with hydrated plasma and sterilized in autoclave (fully processed) according to the present invention, after a period of time of 8 minutes per side according to the conditions of example 1, which has approximately 95% surface coverage. All AFM images are from dry samples.

DETAILED DESCRIPTION OF THE INVENTION As mentioned above, the present invention relates to a sili-cona hydrogel contact lens having a silicate-containing coating and a method of making it, coating that improves hydrophilicity and lipid resistance / lens proteins. Thus, the silicate-containing coating can be worn in the eye for a prolonged period of time, for more than 24 hours in a row, a lens that could not otherwise be carried comfortably in the eye. The surface treatment of silicone hydrogel lenses is complicated by the fact that, although silicone hydrogel lenses can be treated with plasma in a non-hydrated state, such lenses, unlike their non-hydrogel counterparts, swell afterwards. by solvent extraction and hydration, which can cause the dimensions of the lens to change substantially after coating. In fact, hydration can cause the lens to swell from about 10 to more than about 20 percent or more, depending on the ultimate water content of the lens. In addition to the swelling of the lens during solvent extraction and hydration, it has also been found that the subsequent autoclaving of the hydrated lens, a common way of sterilizing lenses during the fabrication of packaged lenses, substantially affects the surface of the plasma-modified lens. The present invention relates to a surface modified silicone hydrogel lens having a silicate-containing coating that exhibits desirable coating characteristics, even after the lens has been extracted, hydrated, and autoclaved. In particular, a silicone hydrogel contact lens is provided with a silicate-containing coating having a mosaic-like configuration of relatively flat plates surrounded and separated by relatively narrow spaces or fissures where (i) the plates provide a cover surface as an average of between about 40 percent to 99 percent, and (ii) the cracks have a peak-to-valley distance on average of between 100 and 500 angstroms. These coating characteristics of a fully processed lens, after surface treatment, hydration, and sterilization, can be observed and determined by viewing a 50x50 micron square image under atomic force microscopy (AFM) as described in detail below. The invention is applicable to a wide variety of silicone hydrogel contact lens materials. Hydrogels in general are a known class of materials that include hydrolyzed crosslinked polymer systems containing water in a state of equilibrium. The silicone hydrogels generally have a water content greater than about 5 weight percent and more commonly between about 10 to about 80 weight percent. Such materials are usually prepared by polymerizing a mixture containing at least one monomer containing silicone and at least one hydrophilic monomer. Typically, the silicone-containing monomer or the hydrophilic monomer functions as a crosslinking agent (a crosslinking agent being defined as a monomer having multiple polymerizable functionalities) or a separate crosslinking agent may be employed. Silicone-containing monomer units applicable for use in the formation of silicone hydrogels are known in the art and numerous examples are set forth in U.S. Patent Nos. 4,136,250; 4,153,641; 4,740,533; 5,034,461; 5,070,215; 5,260,000; . 310,779; and 5,358,995. Examples of applicable silicon-containing monomer units include bulky polysiloxane alkyl (meth) acrylic monomers. An example of bulky polysiloxane alkyl (meth) acrylic monomers is represented by the following formula I: (I) where: X designates -O- or -NR-; each R1B independently designates hydrogen or methyl; each R19 independently denotes a lower alkyl radical, phenyl radical or a group represented by R? _ '-Si-R, 9' R, 9 ' where each R19, independently denotes a radical fe- nyl or lower alkyl; and h is 1 to 10. Some preferred bulky monomers are methacryloxypropyl tris (trimethylsiloxy) silane or tris (trimethylsiloxy) silylpropyl methacrylate, sometimes referred to as TRIS, and tris (trimethylsiloxy) silylpropyl vinyl carbamate, sometimes referred to as TRIS-VC. Another class of representative silicon-containing monomers includes vinyl carbamate containing silicon or vinyl carbamate monomers such as 1,3-bis [4-vinyloxycarbonyloxy) but-l-yl] tetramethyl-disiloxane; 3- (trimethylsilyl) propyl vinyl carbonate; 3- (vinyloxycarbonyl) propyl [tris (trimethylsiloxy) silane]; 3- [tris (trimethylsilyloxy) silyl] propyl vinyl carbamate; 3- [tris (trimethylsilyloxy) silyl] propyl allyl carbamate; 3- [tris (trimethylsilyloxy) silyl] propyl vinyl carbonate; t-butyldimethyl-siloxyethyl vinyl carbonate; trimethylsilylethyl vinyl carbonate; and trimethylsilylmethyl vinyl carbonate. An example of vinyl carbonate containing silicon or vinyl carbamate monomers is represented by formula II: (II) O (CH2) q. O AND R20 where: Y 'designates -0-, -S- or -NH-; RSl denotes an organic radical containing silicone; R20 denotes hydrogen or methyl; d is l, 2, 3 or 4, - and q is 0 or l. Suitable organic silicone-containing radicals include the following: ____ »ilar ^ .- a - (CH2) n 'Si [(CH2) m.CH3] 3; - (CH2) n. Yes [OSi (CH2 > m.CH3] 3; - (CH2) n- | -S_2-2 0 _-Lt-R21 R22; and where: R? 1 denotes (CH2) P 'O, where p 'is 1 to 6; R 27 denotes an alkyl radical or a fluoroalkyl radical having from 1 to 6 carbon atoms; e is from 1 to 200; n 'is 1, 2, 3 or 4; and m 'is 0, 1, 2, 3, 4 or 5. An example of a particular species within formula II is shown with formula III.

= £ Saa_H _____________________ g | É (III) Another class of silicon-containing monomers includes polyurethane-polysiloxane ma-chromonomers (sometimes also referred to as prepolymers), which may have hard-soft-hard blocks such as traditional urethane elastomers. They can be finished with a hydrophilic monomer such as HEMA. Examples of such silicone urethanes are described in several publications, including Lai, Yu-Chin, "The Role of Bulky Poly-siloxanylalkyl Methacrylates in Polyurethane-Polysiloxane Hy-drogels", Journal of Applied Polymer Science, vol. 60, 1193-1199 (1996). The published PCT application number WO 96/31792 describes examples of such monomers, which description is incorporated herein by reference in its entirety. Other examples of silicone urethane monomers are represented by formulas IV and V: (IV) E (* D * A * D * G) a * D * A * D * E - or (V) E (* D * G * D * A) a * D * G * D * E '; where: ™ "'' '- *" D denotes an alkyl diradical, a diradical alkyl cycloalkyl, a diradical cycloalkyl, an aryl diradical or a diradical alkylaryl having from 6 to 30 carbon atoms; G denotes an alkyl diradical, a cycloalkyl diradical, a cycloalkyl alkyl diradical, an aryl diradical or a diradical alkylaryl having from 1 to 40 carbon atoms and which may contain ether, thio or amine bonds in the main chain; * denotes a urethane or ureide bond; a is at least 1; A denotes a divalent polymeric radical of formula VI: (VI) where: each Rs independently denotes an alkyl or fluoro-substituted alkyl group having 1 to 10 carbon atoms which may contain ether bonds between carbon atoms; m 'is at least 1; Y - - i go- IMÉ-iTlftirii '____ J¡ _______ p is a number that provides a radical weight of 400 to 10,000; each of E and E 'denotes independently a polymerizable unsaturated organic radical represented by formula VII: R23 F-24 (CH2) "- (X) X- (Z) i- (Ar) y-R25- 1.4 (VII) where: R23 is hydrogen or methyl; R24 is hydrogen, an alkyl radical having 1 to 6 carbon atoms, or a radical -CO-Y-T39 where Y is -0-, -S- or -NH-; R25 is a divalent alkylene radical having from 1 to 10 carbon atoms; R26 is an alkyl radical having from 1 to 12 carbon atoms; X denotes -CO- or -0C0-; 2 denotes -O- or -NH-; Ar denotes an aromatic radical having 6 to 30 carbon atoms; is from 0 to 6; x is O or 1; and it is O or 1; and z is O or 1. A more specific example of a urethane monomer containing silicone is represented by the formula (VIII): (VHI) where m is at least 1 and is preferably 3 or 4, a is at least 1 and preferably is 1, p is a number that provides a radical weight of 400 to 10,000 and is preferably at least 30, R27 is a diradical of a diisocyanate after the extraction of the isocyanate group, such as the diradical diisocyanate of isophorone, and each E "is a group represented by: A preferred silicone hydrogel material includes (in the voluminous monomer mixture which is copolymerized) from 5 to 50 percent, preferably from 10 to 25, by weight of one or more silicone macromonomers, from 5 to 75 percent, preferably from 30 to 60 percent by weight of one or more polysiloxane alkyl (meth) acrylic monomers, and from 10 to 50 percent, preferably from 20 to 40 percent, by weight of a hydrophilic monomer. In general, the silicone macromonomer is a poly (organosiloxane) terminated with an unsaturated group at two or more ends of the molecule. In addition to the end groups in the above structural formulas, U.S. Patent No. 4,153,641 to Deichert et al. Discloses additional unsaturated groups, including acryloxy or methacryloxy. Preferably, the silane macromo-nomer is a vinyl carbonate containing silicon or vinyl carbamate or a polyurethane-polysiloxane having one or more hard-soft-hard blocks and terminated with a hydrophilic monomer. Hydrophilic monomers suitable for use in silicone hydrogels include, for example, unsaturated carboxylic acids, such as methacrylic and acrylic acids.; substituted acrylic alcohols, such as 2-hydroxyethyl-methacrylate and 2- hydroxyethyl acrylate; vinyl lactams, such as N-vinyl pyrrolidone; and acrylamides, such as methacrylamide and N, N-dimethylacrylamide. Other examples are the hydrophilic vinyl carbonate or vinyl carbamate monomers described in U.S. Patent Nos. 5,070,215, and the hydrophilic oxazolone monomers described in U.S. Patent No. 4,910,277. Other suitable hydrophilic monomers will be apparent to those skilled in the art. Preferably, the lens material used in the present invention is not fluorinated or has relatively few fluorine atoms. Although it has been indicated that the fluorination of some monomers used in the formation of silicone hydrogels reduces the accumulation of deposits in contact lenses made from them, highly fluorinated materials can not be used, because of their particular nature. chemical, to produce the silicate-containing coatings according to the present invention. The present invention is also not applicable to siloxane fumarate hydrogel compositions according to U.S. Patent No. 5,420,324. Without wishing to be bound by theory, it is proposed that the surface silicone content of smoked-siloxane lenses is too high for the formation of a sufficiently flexible silicate, so that the silicate surface formed by oxidative plasma treatment is too glass-like, delaminating during the next treatment. The silicon content of the treated surface layer can be a result of the voluminous chemistry of the composition, which includes its hydrophobic and hydrophilic portions, and / or a result of a surface layering phenomenon leading to a relative enrichment of layers with respect to different monomers or elements. Without wishing to be bound by theory, it is estimated that the desired coating, in a fully processed coating according to the present invention, has sufficient silicate content to obtain the desired surface properties, such as wettability and resistance to deposition, and sufficient polymer content. to allow sufficient flexibility during swelling and sufficient interfacial cohesion during heat sterilization to avoid delammation. The relative balance, in the coating, of hydrophobic and hydrophilic portions can also affect the coating resistance to delamination during thermal and hydrodynamic expansion or stress. In general, the Hydrodynamic expansion of hydrogels in water is a function of the type and amount of the hydrophilic polymer content; and the thermal expansion is a function of the silicone polymer content. If the first increases, the second can decrease, or vice versa. Thus, the chemistry of the silicate or film containing coating in the final product is not completely silicate and part of the original material can remain in modified form. However, in general the coating formed by plasma treatment, the original polymeric character of the material is changed to a harder glass-like material. To determine the applicability of the present invention to a particular silicone hydrogel material, the lens can be treated under two groups of very diverse plasma conditions, a first "low and slow" plasma treatment and a second plasma treatment. "hot and fast". If after the steps of plasma treatment, hydration, and heat sterilization (referred to as "complete treatment"), a silicon coating can be obtained, then a certain additional adjustment of the process conditions should be able to achieve a lens coating with surface characteristics according to the present invention expiration In general, a "low and slow" surface treatment tends to be relatively more effective for a lens with a relatively higher silicon content; A "hot and fast" surface treatment is relatively more effective for a lens with a relatively lower silicon content. By "low and slow" surface treatment is meant a relatively shorter time, higher pressure, and lower flow rate, conditions designed to relatively minimize the disruption of covalent bonds while modifying the substrate, thereby leaving more polymer in the Coating interface with the lens material. "Low and slow" exemplary conditions for plasma treatment (in a plasma chamber as used in the following examples) are 100 watts at 0.3 to 0.6 Torr, 1-2 minutes per side, with 100 to 300 ccem (standard cubic centimeters per minute) in an air / water / peroxide atmosphere (air bubbled through an 8% hydrogen peroxide solution in HPLC grade water). By "hot and fast" treatment is meant relatively higher wattage, lower pressure and longer time, conditions designed to relatively maximize surface modification. The "hot and fast" conditions exemplary for plasma treatment are 400 watts at 0.1 to 0.4 Torr, 10 minutes per side, with 200 to 500 ccem in the atmosphere indicated above. The existence of a silicate-containing coating can be evidenced by a recognizable or statistically significant change in surface roughness (RMS), a visual change in the surface morphology evidenced by AFM, such as the formation of superficial plaques, or by a statistically significant difference in XPS data for a lens before treatment compared to a fully processed lens, notably by a difference in oxygen and / or silicon content (which includes the appearance of a silicate peak). A preferred test for the formation of a coating is a change of 1 to 5% in oxygen content, within a confidence level of 95%. As indicated above, if some silicate coating can be formed on the fully processed lens (after hydration and heat sterilization) by "low and slow" treatment conditions or "hot and fast" treatment conditions, then it is possible generally obtain a coating according to the present invention by following adjustments of the process, without undue experimentation, as will be understood by those skilled in the art. It is noted that the formation of a Silicate coating merely after plasma treatment is not the test for applicability, since the subsequent delamination during heat sterilization can be produced in such a way that no coating on the fully processed lens would be evident. Manufacturing of lenses. Contact lenses can be manufactured according to the present invention, employing various conventional techniques, to obtain a shaped article having the desired posterior and anterior lens surfaces. Centrifugal casting methods are disclosed in U.S. Patent Nos. 3,408,429 and 3,660,545; Preferred static casting methods are described in U.S. Patent Nos. 4,113,224 and 4,197,266. The curing of the monomeric mixture is often followed by a machining operation to obtain a contact lens having a desired final configuration. For example, U.S. Patent No. 4,555,732 discloses a process in which an excess of a monomer mixture is cured by centrifugation in a mold to form a shaped article having an anterior lens surface and a relatively thick thickness. big. The back surface of the cured centrifuged article is then cut around to provide a contact lens. which has the back surface and the desired thickness of the lens. In addition, machining operations can follow cutting around the lens surface, for example, edge finishing operations. Figure 1 illustrates a series of steps of the manufacturing process for static casting of lenses, where the first step is the machining (1) by which, based on the design of a given lens, mechanical tools are manufactured by machining operations and polished traditional. These mechanical tools are then used in injection or compression molding to produce a plurality of thermoplastic molds which in turn are used to empty the desired lenses from polystyrene compositions. Thus, a set of mechanical tools can produce a large number of thermoplastic molds. The thermoplastic molds can be arranged after forming a single lens. The metal molds made during machining (1) are then used for anterior molding (2) and subsequent molding (3) to produce, respectively, a front section of the mold to form the desired anterior surface of the lens and a posterior section of the mold to form the desired rear surface of the lens. Then, during the emptying operation (4), a monomer mixture (5) is injected into the anterior section of the mold, and the back section of the mold is pressed down and fixed at a given pressure to form the desired lens shape. The fixed molds can be cured by exposure to UV light or other energy source for some period of time, preferably by transporting the molds through a curing chamber, after which the clamps are removed. After producing a lens having the desired final shape, it is desirable to remove the residual solvent from the lens prior to the edge finishing operations. This is because, typically, an organic diluent is included in the initial monomer mixture to minimize the phase separation of polymerized products produced by polymerization of the monomer mixture and to lower the glass transition temperature of the reactive polymer mixture, which allows a more efficient curing process and ultimately results in a more uniformly polymerized product. Sufficient uniformity of the initial monomer mixture and the polymerized product are of particular interest for silicone hydrogels, primarily due to the inclusion of silicone-containing monomers which may tend to be separated from the hydrophilic comonomer. Suitable organic diluents include, for example, monohydric alcohols, with C 6 -C 10 straight chain aliphatic monohydric alcohols being especially preferred, such as n-hexanol and n-nonanol; diols such as ethylene glycol; polyols such as glycerin; ethers such as diethylene glycol monoethyl ether; ketones such as methyl ethyl ketone; esters such as methyl enanthate; and hydrocarbons such as toluene. Preferably, the organic diluent is sufficiently volatile to facilitate its removal from an article cured by evaporation at or near ambient pressure. Generally, the diluent is included in 5 to 60% by weight of the monomer mixture, with 10 to 50% by weight being especially preferred. The cured lens is then subjected to solvent extraction (6), which can be performed by evaporation at or near ambient pressure or under vacuum. A high temperature can be used to shorten the time necessary to evaporate the diluent. The conditions of time, temperature and pressure for the solvent extraction step will vary depending on factors such as the volatility of the diluent and the specific monomeric components, as can be easily determined by those skilled in the art. According to a preferred embodiment, the temperature used in the extraction step It is preferably at least 50 ° C, for example, 60 to 80 ° C. A series of heating cycles can be used in a linear oven under inert gas or vacuum to optimize the efficiency of solvent extraction. The cured article after the diluent extraction step should contain no more than 20% by weight of diluent, preferably no more than 5% by weight or less. After extraction of the organic diluent, the lens is then subjected to mold extraction and optional machining operations (7) according to the embodiment of Figure 1. The machining step includes, for example, burnishing or polishing an edge and / or surface of the lens. Generally, such machining processes can be performed before or after removing the article from a mold part. Preferably, the lens is removed by drying the mold using vacuum pliers to lift the lens from the mold, after which the lens is transferred by means of mechanical pliers to a second set of vacuum pliers and placed against a rotating polishing surface. the surface or the edges. The lens can then be returned to machine the other side of the lens. After the extraction operations of the mold of machining (7), the lens is subjected to surface treatment (8), preferably by means of RF oxidative treatment with plasma of the lens surface using a gas containing oxygen. The plasma treatment involves passing an electric discharge through a low pressure gas. The electric discharge is usually carried out at radiofrequency (typically, 13.56 MHz), although microwave and other frequencies can be used. This electrical discharge is absorbed by atoms and molecules in their gas state, thus forming a plasma that interacts with the surface of the contact lens. In the prior art, an oxidizing plasma employing, for example, 02 (oxygen gas), water, hydrogen peroxide, air, etc., or mixtures thereof, has been used to attack the surface of the lens, creating radicals and functional groups oxy-dice. It is known that such oxidation makes the surface of a silicone lens more hydrophilic; however, the bulky properties of the silicone materials may remain evident on the surface of the lens or may be evident after a relatively short period of use. For example, when the oxidation is relatively superficial, the silicone chains adjacent to the lens surface are able to migrate and / or rotate, thus exposing hydrophilic groups. fobos to the external surface even in a completely extracted polymer. In addition, an oxidized surface may lose the coating due to delamination during the additional treatment steps, including auto-key sterilization. In contrast, the plasma conditions of the present invention are regulated and fixed to obtain the desired combination of ablation and oxidation of the surface material, based on the careful quality control of the resulting coating. Therefore, a relatively thick coating is achieved, a permanent barrier between the underlying silicone materials and the outer lens surface in the final product. A plasma for the surface modification of the lens is initiated by a low energy discharge. The collisions between free energetic electrons present in the plasma cause the formation of ions, excited molecules, and free radicals. Such species, once formed, can react with themselves in the gas phase as well as with other molecules in ground state. Plasma treatment can be understood as an energy-dependent process involving gas energy molecules. For chemical reactions to take place on the surface of the lens, the required (element or molecule) in terms of charge state and particle energy. Radiofrequency plasmas generally produce a distribution of energetic species. Typically, "particle energy" refers to the measurement of the so-called Boltzman-type energy distribution for energy species. In a low density plasma, the energy distribution of the electrons can be related by the ratio of the electric field strength that holds the plasma to the discharge pressure (E / p). The power density of plasma P is a function of wattage, pressure, gas flow rates, etc., as experts will appreciate. The background information on plasma technology, incorporated herein by reference, includes the following: A. T. Bell, Proc. Intl. Conf. Phenom. Ioniz Gases, "Chemical Reaction in Nonequilibrium-Plasmas", 19-33 (1977); J. M. Tibbitt, R. Jensen, A. T. Bell, M. Shen, Macromolecules, "A Model for the Kinetics of Plasma Polymerization", 3,648-653 (1977); J. M. Tibbitt, M. Shen, A. T. Bell, J. Macromol. Sci. -Chem., "Structural Char-acterization of Plasma-Polymerized Hvdrocarbons", AlO, 1623-1648 (1976); C. P. Ho, H. Yasuda, J. Biomed. Mater. Res., "Ul trathin coating of plasma polymer of methane applied on the surface of silicone contact lenses ", 22, 919-937 (1988), H. Kobayashi, AT Bell, M. Shen, Macromolecules," Plasma Polymerization of Saturated and Unsaturated Hydrocarbons ", 3, 277-283 (1974); Chen, U.S. Patent No. 4,143,949, March 13, 1979, "Process for Putting Hydrophilic Coating on a Hydrophobic Contact Lens"; and H. Yasuda, HC Marsh, Bumgarner MO, N. Morosoff, J. of Appl. Poly Sci., "Polymerization of Organic Compound in an Electroless Glow Discharge. SAW . Acetylene wi th Unusual Comonomers ", 19, 2845-2858 (1975) Based on this previous work in the field of plasma technology, one can understand the effects of changing the pressure and discharge power at the rate of modification of The rate generally decreases as the pressure increases, so that as the pressure increases the value of E / p, the ratio of the electric field strength that keeps the plasma to the gas pressure decreases and produces a decrease in the average energy of the electrons The decrease in the energy of the electrons in turn produces a reduction in the rate coefficient of all the electron-molecule collision processes.Another consequence of the increase in pressure is a decrease in the density of electrons. jjg ^ As long as the pressure remains constant, there must be a linear relationship between electron density and power. In practice, contact lenses receive surface treatment by placing them, in their unhydrated state, into a luminescent electric discharge reaction vessel (e.g., a vacuum chamber). Such reaction tanks are available in the market. The lenses can be supported inside the container in an aluminum tray (which acts as an electrode) or with other support devices designed to regulate the position of the lenses. The use of specialized support devices that allow surface treatment of both sides of a lens are known in the art and can be used in the present invention. The gas used in the plasma treatment includes oxidizing means such as, for example, air, water, peroxide, 02 (oxygen gas), or combinations thereof, at an electric discharge frequency of, for example, 13.56 MHz, suitable - between about 100-1000 watts, preferably from 200 to 800 watts, more preferably from 300 to 500 watts, at a pressure of about 0.1-1.0 Torr. The time of plasma treatment is greater than 4 minutes per side, preferably at least approximately 5 minutes per side, more preferably approximately 6 to 60 minutes per side, most preferably from about 8 to 30 minutes per day for effective but efficient manufacturing. It is preferred to use a relatively "strong" oxidizing plasma in this initial oxidation, for example, room air introduced through a hydrogen peroxide solution of 3 to 30% by weight, preferably 4 to 15%, more preferably 5 to 10%, preferably at a flow rate of 50 to 500 ccem, more preferably 100 to 300 ccem. Such plasma treatment directly results in a relatively thick smooth film that can be approximated to the point where the optical clarity is affected, ie, approximately 1500 angstroms. Preferably, the thickness of the post-plasm coating should be greater than 1000 angstroms, since substantial thickness will be lost during the next treatment. After hydration and sterilization in an autoclave, as will be better explained below, the surface will crack and the thickness can be reduced by more than 50 percent, even up to 90 percent or more, of the initial thickness of the coating.

To obtain the desired coating, it may be necessary to regulate the process parameters to obtain a combination of ablation and glass formation that results in the desired coating after undergoing additional processing steps. The thickness of the coating is sensitive to the flow velocity of the plasma and the temperature of the chamber. Higher flow rates tend to produce more ablation; lower pressures tend to produce thicker coatings outside the plasma chamber. However, higher temperatures may tend to result in a surface that is less vitreous and less cohesive. Since the coating depends on several variables, the optimal variables to obtain the desired or optimum coating may require some adjustment. If a parameter is adjusted, a compensatory adjustment of one or more other parameters may be appropriate, so that some routine test experiments and iterations thereof may be necessary to achieve the coating according to the present invention. However, such adjustment of process parameters, in light of the present disclosure and the state of the art in plasma treatment, should not involve undue experimentation. As indicated above, relationships General among the parameters of the process are known to the experts, and the technique of plasma treatment has developed a lot in recent years. The following examples set forth the applicant's best mode for forming the coating on a silicone hydrogel lens. After the surface treatment step (8) in the embodiment of Figure 1, the lens can be subjected to extraction (9) to remove residues from the lenses. Generally, in the manufacture of contact lenses, part of the monomer mixture does not polymerize completely. The incompletely polymerized material from the polymerization process may affect optical clarity or may be detrimental to the eye. The residual material may include solvents not completely removed by the above operation of solvent extraction, unreacted monomers of the monomer mixture, oligomers present as by-products of the polymerization process, or even additives that may have migrated from the mold used to form the lens . Conventional methods for extracting such residual materials from the polymerized contact lens material include extraction with an alcohol solution for several hours (for removal of the residual hydrophobic material) separated.

Extraction guide with water (for extraction of the residual hydrophilic material). Thus, part of the alcohol extraction solution remains in the polymer network of the contact lens polymerized material, and should be removed from the lens material before the lens can be safely and comfortably carried in the eye. Extraction of the alcohol from the lens can be achieved by using water heated for several hours. The extraction should be as complete as possible, since the incomplete removal of the residual lens material can adversely contribute to the useful life of the lens. In addition, such residues can impact lens performance and comfort by interfering with the optical clarity or the desired uniform hydrophilicity of the lens surface. It is important that the selected extraction solution does not adversely affect the optical clarity of the lens in any way. For optical clarity, the level of clarity observed when the lens is visually inspected is subjectively understood. After extraction (9), the lens is subjected to hydration (10) in which the lens is completely hydrated with water, buffered saline, or the like. When the lens is completely hydrated in the end (where the lens can typically expand from 10 to about 20 percent or more), the coating remains intact and attached to the lens, providing a durable hydrophilic coating that has been found to be resistant to delamination. After hydration (10), the lens can undergo cosmetic inspection (11) where expert inspectors inspect contact lenses for clarity and absence of defects such as holes, particles, bubbles, cuts, cracks. The inspection is preferably done at a 10X magnification. After the lens has passed the cosmetic inspection steps (11), the lens is ready for packaging (12), in a vial, bubble wrap, or other container to hold the lens in a sterile condition for the consumer. Finally, the packaged lens is subjected to sterilization (13), sterilization which can be carried out in a conventional autoclave, preferably under a sterilization cycle with air pressure, sometimes called an air-steam mixing cycle, as -The experts will. Preferably the autoclave sterilization is carried out at 100 ° C to 200 ° C for a period of 10 to 120 minutes. After sterilization, the dimension of ___ The sterilized lenses can be checked before storage. After the steps of hydration and sterilization, the silicate-containing coating produced by plasma treatment has been modified to its final form, in which the coating has a mosaic configuration of protruding plates surrounded by receding cracks, similar in appearance to islands. little spaced surrounded by rivers. When viewing an image of 50x50 microns square by atomic force microscopy, the distances from peak to valley (or depth) of cracks is on average between approximately 100 and 500 angstroms, and the plate coverage (or surface coverage) is on average between approximately 40% and 99%. It can be considered that the depth of the fissures is a measurement of the "coating thickness", where the fissures expose the underlying hydrogel material under the glass-like coating, containing silicate. Preferably, the peak to valley distances of the fissures is on average between 150 and 200 angstroms and preferably the plate coverage is on average about 50% to 99 percent, more preferably 60 to 99%. By the term "as average" is meant an average of the measurements of controlled batches of lenses taken during commercial manufacture, based on average measurements of each lens in the optical zone. Preferably, the average for each lens is calculated based on the evaluation of three 50x50 micron square images per side of each lens, as in the following examples. By the term "controlled manufacture" or "controlled process" is meant that the manufactured product is consistently produced and subjected to quality control so that the average values are within a pre-selected band, or within a pre-selected band of specifications, with respect to the depth of the fissures and the coverage of plates. In terms of consistency, preferably at least 70%, more preferably at least 80%, most preferably at least 90% of the manufactured lenses, with a confidence level of 95%, should meet the indicated bands of coating thickness and coverage of plates. Preferably, the average value, for the surface coverage and the thickness of the coating, of the manufactured lenses should be within the indicated bands within a confidence level of 90%, more preferably within a confidence level of 95% . Example 1 _________ This example describes a representative silicone hydrogel lens material used in the following examples. The formulation of the material is shown in Table 1 below. Table 1 The above designations indicate the following materials: TRIS-VC Tris (trimethylsiloxy) siliipropyl vmilo carbamate NVP N-vmil pyrrolidone it has been previously described in U.S. Patent No. 5,534,604. VINAL N-vinyloxycarbonyl alanine Darocur Darocur-1173, a UV initiator Color agent 1,4-bis [4- (2-methacryloxyethyl) phenylamino] anthraquinone Example 2 This example illustrates a process for surface modification of a contact lens according to present invention. Hydrogel silicone lenses made from the formulation of Example 1 above were molded by casting polypropylene molds. Under an inert nitrogen atmosphere, 45 μl of the formulation was injected onto a clean concave half of a polypropylene mold and covered with the complementary convex half of the polypropylene mold. The mold halves were compressed at a pressure of 4921 g / cm2 (70 pounds per square inch) and the mixture cured for approximately 15 minutes in the presence of UV light (6-11 mW / cm2 measured with a Spectronic UV meter). The mold was exposed to UV light for approximately 5 additional minutes. The upper half of the mold was removed and the lenses were kept at 60 ° C for 3 hours in a forced air oven. to extract n-hexanol. After, the lens edges were polished to a ball for 10 seconds at 2300 rpm with a force of 60 g. The lenses were then treated with plasma as follows: the lenses were placed concave side up on an aluminum-coated tray and the tray was placed in a plasma treatment chamber. The atmosphere was produced by passing air at 400 ccem to the chamber through a peroxide solution at 8%, giving rise to a gaseous mixture of air / H20 / H203. The lenses were treated with plasma for a period of 8 minutes (350 watts, 0.5 Torr). The chamber was then filled at ambient pressure. The tray was removed after the camera, the lenses were turned over, and the procedure for treating the other side of the lenses with plasma was repeated. Lenses were analyzed directly from the plasma chamber and after the complete treatment. The complete treatment included, after plasma treatment, extraction, hydration and sterilization in an autoclave. In the extraction, isopropanol was used at room temperature for 4 hours (commercial manufacture is preferred a minimum of 48 hours followed by extraction in water at approximately 85 ° C for 4 hours). The lenses were then immersed in solu- saline buffered for hydration. The autoclave sterilization was performed with the lenses, inside vials, immersed in an aqueous solution of packaging. The plasma chamber was a DC DC RFGD camera manufactured by Branson GaSonics Division (model 7104). This camera was a flat cold equilibrium configuration that had a maximum power of 500 watts. All lenses were pre-puffed at 0.01 Torr before any plasma treatment of the residual air in the chamber. This process reduced the relative treatment level of the polymer by controlling the gas pressure. All lenses of this study were analyzed as received. The pre-plasma and post-plasma lenses were analyzed dry. The fully processed lenses were removed from the vials and scrubbed in HPLC grade water in a static mode for a minimum of 15 minutes. The back of three lenses and the front of three lenses of the pre-plasma, post-plasma, and fully processed lenses of each batch were analyzed by X-ray photoelectron spectroscopy (XPS). The XPS data was acquired by a Physical Electronics [PHL] Model 5600 spectrometer. To collect the data, the instrument's aluminum anode was operated at 300 watts, 15 k, and 20 mA. The Al Ka line was the source of monochromatic excitation using a toroidal lens system. The X-ray monochromator used a 7 mm filament to focus the X-ray source that increases the need for charge dissipation by using a neutralizer. The base pressure of the instrument was 2.0 x 10-10 Torr whereas during operation it was 1.0 x 10-9 Torr. A semi-spherical energy analyzer measures the kinetic energy of electrons. The practical sampling depth of the instrument, with respect to carbon, at a sampling angle of 45, is approximately 74 angstroms. The charge of all the elements was corrected to the CHX peak of carbon bond energy of 285.0 eV. Each of the specimens modified by plasma was analyzed by XPS using a low resolution analysis spectrum [0-1100 eV] to identify the elements present on the surface of the sample. The high resolution spectra were performed on the elements detected from the low resolution scans. The elemental composition was determined from the high resolution spectra. The atomic composition was calculated from the zones under the photoelectron peaks after sensitizing the zones with the transmit function of the instrument and atomic cross sections for the orbital of interest. Since XPS does not detect the presence of hydrogen or helium, these elements will not be included in any calculation of the atomic percentages. The data on the atomic composition are shown in table 2.

TABLE 2 ? ----___-_-_______ l Each experiment consisted in verifying 6 lenses of the sample lot of 50 to 100 lenses. The study spectra for the pre-plasma lenses of experiments 1 to 3 contain photoelectronic peaks indicative of oxygen, nitrogen, carbon and silicon. The silicon peak position 2p3 / 2 (102.4 Ev) indicates that the silicon detected on the surface originated from silicone derivatives. The study spectra for the post-plasma lenses of experiments 1 to 3 contain photoelectronic peaks indicative of oxygen, nitrogen, carbon, silicon and fluorine. Fluoride is a byproduct of plasma ablation of Teflon beads that support the trays used to hold the lenses. The photoelectronic peak position of silicon 2p3 / 2 (103.7 Ev) indicates that the silicon detected on the surface originated at * a¿ »g ^^^ mi- - BÉÉÉáSai _____. from silicates, verifying the presence of a coating. As evidenced, slight differences in elemental analysis for different experiments may be due to slight variations in plasma treatment parameters, the position in the chamber, or as a result of inherent surface properties of the lenses of this particular lot. In addition, atomic force microscopy (AFM) was used to study the morphology of the surfaces of the contact lens. AFM operates by measuring nano-scale forces (10-9N) between a sharp probe and atoms on the lens surface. The probe is mounted on a cantilevered substrate. The deflection of the cantilever, measured by a laser detection system, is treated to generate height information. While height information is collected, the probe is scanned in the x-y plane to generate a three-dimensional topographic image of the lens surface. In the optical zone of each lens, three images were sampled on both sides of the lens.

The fraction of the lens surface that is covered with the coating is termed "plate coverage" or "surface coverage". This measurement is sometimes made easily by looking at a histogram of the surface heights. However, when the coating is too thin (< 10 nm), the Coverage can not be obtained from the histogram. When this occurs, the AFM image in question is compared to previous AFM images whose exact coverage is known. When this visual method is used, the coverage is estimated and is correct within ± 10%. Figure 2 is a topographic image by atomic force microscopy (AFM) showing a lens treated with plasma before further processing by hydration and sterilization in autoclave. The image shows a len-te coating with a smooth surface (100% surface coverage) that looks very similar to the surface before the plasma treatment. This is because most plasma coatings adapt to the original surface. As is evident, the surface is not perfectly smooth. The surfaces have some fine multidirectional stripes due to the machining marks. Figure 3, for comparison with a lens surface according to the present invention, is an atomic force microscopy photograph (AFM) showing a plasma treated lens in autoclave (fully processed) after a period of time of treatment with plasma of only 4 minutes per side, although otherwise comparable to the conditions process clones of this example. The thickness of the coating is only 4 +/- 2 nm thick, with only about 20% coverage. The coloring in the image shows different heights on the surface. The lighter areas correspond to the high characteristics, while the dark areas correspond to the lowered characteristics. In the image of Figure 3, it is evident that the coating has cracked and delaminated, exposing the surface of the lens, thereby showing a relatively smooth surface with barely visible plates. Figure 4 is an atomic force microscopy (AFM) image of a lens treated with plasma after extraction with isopropanol. The thickness of the lens is approximately 100 nm (which will be reduced during autoclave sterilization), and the surface coverage is approximately 50 percent. Since the AFM images are in the dry state, the surface coverage of the extracted and fully processed lenses are comparable. Figure 5 is a topographic image by atomic force microscopy (AFM) (50x50 microns square) showing a lens treated with hydrated plasma and sterilized in autoclave (completely processed according to the present invention). for a period of time of 8 minutes, showing different plates with excellent surface coverage The thickness of the coating is approximately 10 +/- 2 nm thick (100 angstroms) with approximately 95 percent surface coverage The average depth of the fissures in the coating (also called the "coating thickness") were measured directly using AFM software. The thickness of 3-5 islands (arbitrarily selected) in each image is measured and averaged to obtain a general coating thickness for each image. Preferably, RMS roughness of the fully processed lens is less than about 50 nm, more preferably from about 2 to about 25 nm, most preferably 5 to 20 nm This comparison shows that, in addition to other parameters such as pressure or air flow, the time period of plasma treatment is a significant control parameter during plasma treatment for obte The desired coating was compared. Comparative Example 3 Silicon hydrogel lenses were treated with plasma of the formulation of Example 1 above over a period of time of 4 minutes per side and used in a clinical study. Due to the variance of the surface topography of the lenses, some batches showed a smooth surface without evidence of plates when they were inspected using surface image formation by atomic force microscopy (AFM), in which an image of 50x50 square micras of a typical area of the lens equal to 1.5 x 10B square micras. Thirteen lots, representing a complete range of surfaces, were examined and classified as "transitional mosaic" (later "mosaic") and "transitional to smooth" (later "smooth"). Approximately 42 percent of the lenses exhibited a smooth surface. By the term "smooth" with respect to the lens is meant a lens surface that does not have the silicate plates surrounded by valleys or fissures, similar to spaced-apart islands surrounded by rivers. Smooth lenses also included lenses with a surface coverage of less than 30 percent and a valley depth of less than approximately 50 angstroms. Mosaic lenses were those that showed more than 30 percent coverage and a valley depth greater than 50 angstroms. To correlate surface characteristics with clinical performance, the lenses used in the clinical study were classified by the degree of deposition based on information provided by physicians who participated in the study. The grade levels were from 0 to 4 corresponding to increasing levels of deposition by split lamp analysis. For grades 0 and 1, where the number of patients was high, the lenses were separated so that in the middle of the degree the lipids could be checked and in the rest the protein. Since the number of lenses in grades 2, 3 and 4 was much lower, these lenses were cut in half (using a scalpel and gloves) so that in each lens the protein and the lipid could be checked. The data generated in these lenses was duplicated to represent the deposition in the complete lens. The lenses were then taken for 3 months with enzyme cleaning at the end of a week of use and then disinfected with ReNu MPS solution overnight. In some cases, the lens was replaced before 3 months due to the specified reasons. In the other cases, the lens was worn throughout the study. After 3 months, all the lenses were transported (in a dry state) and stored in a refrigerator on arrival. To correlate more surface characteristics with the deposition properties (composition), protein and lipid analyzes of the deposits were performed. The protein analysis was done using the analytical colo-rimétpco BCA (Sigma) method. The method employs protein-induced reduction of Cu (II) to Cu (I). A purple complex (A ^, = 562 nm) is then formed after the addition of bi-cmconinic acid (BCA) to the reduced copper. It is shown that the intensity of the complex is directly proportional in the protein concentration band from 5 μg / ml to 2000 μg / ml. After incubation at 37 ° C, the rate of color development slows down sufficiently to be able to make large amounts of samples in a single pass. The standard protein solution was BSA with a standard concentration band of 0 -200 μg. The analytical protocol was as follows: 1) In the preparation of the standards, an unused lens is removed from a vial, dried in the air and then placed in a plastic centrifuge tube together with standard BSA solution. Also used lenses (also air-dried) are placed in centrifugal tubes. A mixture of BCA / copper (II) sulfate solution is then added to the dried lenses. 2) Then the tubes are placed in a water bath 37 ° C for 15 minutes. After incubation, the purple complex develops. 4) Samples and standards are read at 562 nm. 5) After it is determined the protein concentration from a standard graph of absorbance as a function of concentration (μg). 6) The reported protein results represent the total amount of bound protein. Gas chromatography (GC) is the method by which the total concentration of lipids was determined. Tri-palminytin (C16) was used as the pattern based on the previous GC passes of C12-C22 chain length lipids that showed similar retention times. The standard solution was 1 mg / ml of tripalmitin in methylene chloride where the concentration band for the standards was 0-100 μg. The analytical protocol consisted of the following steps: 1) BF3 / MeOH 1) Hexane extraction Dirty lens > Heat 60 ° C - > Inject to GC and 2) CH2C12 2) Extract solvent The same protocol was used as before for the patterns where an unused lens is placed in a glass test tube with the standard solution. For the rest, the protocol was as follows: 1) When hexane is added to the lens (with heat), the lens will dissolve and eventually precipitate to the bottom of the tube. Two phases will be formed. The lower layer is cloudy (MeOH layer) and the upper layer (hexane layer) is clear. The hexane layer is extracted. The extraction of samples and standards is done twice. The fact that the lens dissolves during this procedure allows to determine the total amount of lipids both on the surface and potentially embedded in the lens matrix. 2) A stream of N2 is used to blow the hexane from the tubes. The samples and standards are then resuspended in 50 μl of hexane. 3) Hexane is passed through the GC (2 μl) to ensure that ridges with appropriate retention times come out. 4) Then an amount of 2 μl of each tube is injected to the GC. The syringe was wiped 10-14 times with hexane between each pass. The retention time of the lipids corresponds to the chain length. They exit Cß- C12, C12, C14 and C16-Cls at increasing intervals. The GC is a Capilary CG 30ft HPR1 column attached to a detector FID (mass), so that you can read the mass corresponding to the crests (in μg). 5) The standard tripalmitin curve shows the peak zone as a function of the amount of lipids (μg). Based on the classification scale of the physician, 86% of the patients participating in the study were classified in grades 0-2, reflecting minimal to null surface deposits. The average protein concentration between these grades was 34.2 μg and the average amount of lipids was 17.5 μg. The detailed results of protein and lipid analysis in the study are shown in Table 3 below: TABLE 3 * The numbers in bold represent the total number of patients with said degree of deposition. The band of protein and lipid concentrations observed demonstrates the individual variability in levels of deposition as well as the variability in the physician's assessment of the degree of deposition. In general, protein levels between all grades remain relatively constant (-35-40 μg) with the exception of grade 0 where the number is a little lower (25 μg). However, the deposition of lipids increases consistently with the degree, indicating that heavy contaminants appear to be deposited as an average more in the lipids than the protein. Of the 24 patients who were classified as grade 3 and 4, 5 deposition had experienced discomfort. No correlation was observed between the age (time of use) of the lens and the degree of deposition. The following table shows the distribution of the lots between the degrees of deposition demonstrating the relative susceptibility of the lenses of the particular lots to the deposition. TABLE 4 Correlating the lens surface with the deposition, the results were as follows: TABLE 5 * These lots were those that were observed in the field as lots with less humidification and / or heavy deposits. These results show that for plasma treated lenses that represent "mosaic" surface characteristics similar to those in Figure 3 of Example 2 above, the percentage of lenses with a deposit rating greater than 2 was 8%, while for lenses also treated with plasma that did not show the "mosaic" surface characteristics of Figure 2 (for example, like the lens shown in Figure 4), the percentage of lenses with a deposit rating greater than 2 was 14%, which shows a statistically significant superiority for the mosaic configuration. Example 4 To show the change in lens wetting properties according to the present invention, measurements were made _1. "_. of the contact angle of an untreated lens (before plasma treatment), a plasma-treated lens (immediately after plasma treatment) and after full processing (which includes hydration and heat sterilization). The contact angle was measured as follows. A platinum (Pt) wire was used to minimize contamination. The Pt wire was passed through a flame on a Bunsen burner until the wire reached a dull red (orange) glow, to ensure that the water (PHLC quality) used in the test was exposed to a clean, fresh, free metal surface. of contamination. Approximately 2 micro-liters of water were transferred from its bottle to the yarn, a process that consisted of dumping the bottle so that the maximum amount of yarn was under the liquid. The water in the yarn was transferred, without dragging along the surface, to a lens made of the material of example 1. Once transferred, a contact angle goniometer NRL-100 Rhamé-Hart was used to measure the contact angle. The baseline was established by regulating the stage height until the baseline was passed between the bottom of the drop and its own reflection. After finding the baseline, the contact angle formed by the drop on the right and on the left was measured. HE added another drop of water to the first drop, and then the contact angles were re-calculated for the left and right sides. The four measurements were averaged. Using this measurement, the lens surface before the treatment exhibited a water contact angle of approximately 90 dynes / cm. After the plasma treatment, the contact angle of the water was 0 dynes / cm. After heat sterilization, the fully processed lens exhibited a contact angle of 72.4 +/- 2 dynes / cm. All measurements were made in dry lenses. Many other modifications and variations of the present invention are possible in the light of the ideas herein. Therefore, it is understood that, within the scope of the claims, the present invention may be practiced in a manner other than that specifically described herein.

Claims (24)

Claims

1. A method to treat the surface of a silicone hydrogel contact lens by controlled manufacture including the following steps: (a) plasma treat the lens with an oxygen containing atmosphere for more than 4 minutes per side, at one watt-je from 100 to 1000 watts and a pressure of 0.1 to 1.0 Torr, to produce a silicate-containing coating, (b) to hydrate the lens by immersing the lens in an aqueous solution, so that the amount of water absorbed by the lens is at least five weight percent of the lens material, (c) subjecting the hydrated lens to heat sterilization, whereby the heat sterilized lens has a silicate-containing coating characterized by a mosaic configuration of protruding, surrounded plaques by receding cracks when viewing an AFM image of 50x50 microns squared, where the depth of the fissures is on average between approximately 100 and 500 angstroms and the plaque cover is like average between approximately 40 and 99 percent.

2. The method of claim 1, wherein the plasma treatment in step (a) is 300 to 500 watts for a period of 6 to 60 minutes per side.

3. The method of claim 1, wherein the plasma treatment in step (a) is for a period of 8 to 30 minutes per side.

4. The method of claim 1, wherein step (b) inflates the lens from 5 to 25 percent.

5. The method of claim 1, wherein the autoclave sterilization is from 100 ° C to 200 ° C for a period of 10 to 120 minutes.

6. The method of claim 1, wherein the depth of the fissures is on average between about 150 and 200 angstrdms.

7. The method of claim 1, wherein the plate coverage is on average between about 60 and 80 hundred.

8. The method of claim 1, wherein at least 80 percent of the lens in a commercially manufactured batch is within said bands for depth of fissures and plate coverage.

9. The method of claim 8, wherein at least 90 percent of the lenses are within said bands.

10. The method of claim 1, wherein the silicone hydrogel includes in a volumetric formula of 5 to 50 weight percent of one or more silicone macromonomers, from 5 to 75 weight percent of one or more polysiloxanilalkyl (meth) monomers ) acrylics, and from 10 to 50 weight percent of a hydrophilic monomer.

11. The method of claim 10, wherein the silane macromonomer is a poly (organosiloxane) terminated with a more saturated group at two or more ends.

12. The method of claim 10, wherein the macromo- ____ t¡ __________________ É__fe? ________ ^^^ ftf £ X ^^^^^^^^^^^ Silane number is a vinyl carbonate containing silicon or vinyl carbamate or a polyurethane-polysiloxane having one or several hard-soft-hard blocks and finished with a hydrophilic monomer.

13. The method of claim 1, wherein the polysiloxane alkyl (meth) acrylic monomers are methacryloxypropyl tris (trimethylsiloxy) silane.

14. The method of claim 1, wherein the hydrophilic monomer is selected from the group consisting of unsaturated carboxylic acids, substituted acrylic alcohols, vinyl lactams, acrylamides, vinyl carbonate or vinyl carbamate, oxazolone monomers, and mixtures thereof.

15. The method of claim 14, wherein the hydrophilic monomer is selected from the group consisting of methacrylic and acrylic acids, 2-hydroxy-ethyl methacrylate and 2-hydroxyethyl acrylate, N-vinyl pyrrolidone, methacrylamide, N, N-dimethylacrylamide, and their mixtures

16. A silicone hydrogel contact lens includes going on a hydrophilic surface having a silicate-containing surface coating characterized by a mosaic configuration of protruding plates surrounded by receding cracks upon viewing an AFM image of 50x50 microns square, where, as a result of a controlled manufacturing process, the average depth of the fissures are on average between approximately 100 and 500 angstroms and the plaque cover is on average between approximately 40 and 99 percent.

17. The contact lens of claim 16, wherein the depth of the fissures is on average between 150 and 200 angstroms.

18. The contact lens of claim 16, wherein the plate coverage is on average between about 60 and 99 percent.

19. The contact lens of claim 16, wherein the silicone hydrogel includes from 30 to 60 weight percent of one or more silicone macromonomers, from 1 to 35 weight percent of one or more polysiloxane alkyl monomers (meth) acrylics, and from 20 to 40 weight percent of a hydrophilic monomer.

20. The contact lens of claim 16, wherein the silane macromonomer is a poly (organosiloxane) terminated with an unsaturated group at two or more ends.

21. The contact lens of claim 16, wherein the silane macromonomer is a vinyl carbonate containing silicon or vinyl carbamate or a polyurethane-polysiloxane having one or more hard-soft-hard blocks and finished with a hydrophilic monomer.

22. The contact lens of claim 16, wherein the polysiloxane alkyl (meth) acrylic monomers are methacryloxypropyl tris (trimethylsiloxy) silane.

23. The contact lens of claim 16, wherein the hydrophilic monomer is selected from the group consisting of unsaturated carboxylic acids, substituted acrylic alcohols, vinyl lactams, acrylamides, vinyl carbonate or vinyl carbamate, oxazolone monomers, and mixtures thereof. ____ ¡_1 ____ É ____________ Í _____

24. The contact lens of claim 16, wherein the hydrophilic monomer is selected from the group consisting of methacrylic and acrylic acids, 2-hydroxyethyl methacrylate and 2-hydroxyethylacrylate, N-vinyl pi-rrolidone, methacrylamide, N, Nd ? methylacrylamide, and its mixtures.