MXPA00000259A - Intracorneal diffractive lens - Google Patents

Abstract

A diffractive ICL made from two different hydrogel materials that are biologically acceptable for long term implantation in the cornea. The first material contains a diffractive surface and has a higher refractive index than the cornea. The second material coats to the diffractive surface of the first material and has a refractive index similar to corneal tissue.

Description

INTRACORNEA LENS, DIFFACTIVA BACKGROUND OF THE INVENTION This invention relates, in general, to the field of intracorneal, optical (SCI) lenses and, more specifically, to optical, diffractive SCIs. The human eye is the simplest terms it works to provide vision by transmitting light through a clear external portion known as the cornea, and focusing the image by means of a crystalline lens on a retina. The quality of the focused image depends on multiple factors including the size and shape of the eye and the transparency of the cornea and the lens. The optical power of the eye is determined by the optical power of the cornea and lens of the lens. In the normal healthy eye, sharp images are formed in the retina (emmetropia). In many eyes the images are formed in the front part of the retina because the eye is abnormally lengthened (axial myopia), or is formed in the posterior part of the retina because the eye is normally short (axial hyperopia). The cornea can also be asymmetric or toric, giving rise to an uncompensated cylindrical refraction error known as corneal astigmatism. In addition, due to the age-related reduction in the accommodation of the lens, the eye can become presbyopic giving rise to the need for a bifocal or multifocal device for correction. In the past, axial myopia, axial hyperopia and the astigmatism corneal generally have been corrected by glasses or contact lenses, but there are several refractive surgical procedures that have been investigated and used since 1949. Barraquer investigated a procedure called keratomileusis that reshaped the cornea using an icrokeratome and a criotorno. This procedure was never widely accepted by surgeons. Another procedure that has obtained wide acceptance is radial and / or transverse incisional keratotomy (RK or AK, respectively). Currently, the use of laser radiation blativas picture to reshape the surface of the cornea (photorefractive keratectomy or PRK) or for photoablation mid-stroma (Laser-Assisted In Situ. Keratomileusis or LASIK) have been approved by the authorities of regulation in the United States and other countries. All of these refractive surgical procedures cause an irreversible modification to the shape of the cornea to effect refractive changes, and if the correct refraction is not achieved by the first procedure should be performed a second procedure or enhancement. In addition, the long-term stability of the correction is variable due to the variability of the biological healing response of the wound between patients. Permanent intracorneal implants made from synthetic materials are also known for the correction of refractive errors of the cornea. For example, U.S. Patent No. 5,123,921 (erblin, et al.) Discloses an intracorneal lens that is implanted within the stroma using an icrokeratome. The lens itself has little refractive power, but changes the refractive power of the cornea by modifying the shape of the anterior surface of the cornea. The microkeratome used to implant this lens is complex and expensive and the lens requires great surgical skill to implant it. Keravision has a series of patents related device intraestrómico ring is used to induce refractive changes in the cornea (see U.S. Patent Nos. 5,505,722, 5,466,260, 5,405,384, 5,323,788, 5,318,047, 5,312, 424, 5,300,118, 5,188,125, 4,766,895, 4,671,276 and 4,452,235). The use of a ring-shaped device prevents implantation of the device within the central optic zone of the cornea, and is implanted in the peripheral groove that is made by a special surgical instrument. The ring itself has no refractive power. Refractive changes are caused by the implanted ring that changes the shape of the anterior surface of the cornea. A variation of the intrastromal ring is known as Gel Injection Adjustable Keratoplasty (GIAK, Adjustable Keratoplasty by Gel Injection) and US Pat. Nos. 5,090,955 are described.

(Simón), 5,372,580 (Simón, et al.) And the publication WIPO No.

WO 96/06584. Instead of a solid device, these publications describe the injection of a biocompatible gel ring around the optic zone of the stroma to effect refractive changes to the cornea by changing the shape of the cornea. These intracranial devices of the prior art all function by changing the shape of the cornea, and the devices themselves have little or no refractive property. As a result, the preparation of a lamellar bed in which these devices are inserted is crucial for the prediction of the refractive result, requiring very precise microkeratomes and other special surgical instruments and a great surgical ability for success. Various intracranial implants having a refractive power are also known. For example, U.S. Patent No. 4,607,617 (Choyce) describes an implant made of polysulfone (refractive index 1633). The high refractive index of the polysulfone in relation to the stromal tissue (1.375) gives rise to an implant that acts as an optical lens that effects a change of refraction for the cornea without depending on a change in the shape of the cornea. This lens was never clinically or commercially acceptable because the polysulfone material is too impermeable to glucose and other metabolites to maintain the corneal tissue prior to implantation. Corneal ulcerations, opacifications and other complications were the clinical result. An implant with which attempts are made to solve the complications of polysulfone implants is described in U.S. Patent No. 4,624,669 (Grendahl). This implant contains a plurality of microfenestrations or micro openings that allow the flow of glucose and other metabolites through the lens. However, in animal studies, microfenestrations were filled with keratocytes that created opacities, giving rise to a scattering of light and unacceptable visual precisions. As a result, this implant was never commercially developed. In an attempt to limit damage to the anterior cornea and prevent inward growth of keratocytes, U.S. Patent No. 5,628,794 (Lindstrom) describes a multifocal, refractive implant of limited diameter (2.5 mm) for the correction of presbyopia, made of a rigid material that has fenestrations, the implant and the fenestrations being coated with a hydrogel material. The inventors are unaware of the clinical data of this lens. This multifocal lens of limited diameter is not clinically acceptable for monofocal correction of myopia or hyperopia in many patients with normal pupil size under normal ambient light conditions. Previous attempts to correct presbyopic vision have generally been limited to glasses and contact lenses. Currently, clinical investigations were initiated for a monofocal hydrogel with low water content (approximately 45%), limited diameter (less than 2.5 mm) incrustation that effectively creates a multifocal cornea. These early clinical investigations, however, have not been stimulated due to compromised distance vision and unacceptable multifocal vision. These lenses are described in U.S. Patent Nos. 5,196,026 and 5,336,261 (Barret et al). Despite these previous attempts to make an adequate corneal implant, there remains a need for a safe and biocompatible intracorneal lens that does not require implantation through a microkeratome and does not depend on the changes in shape induced for the cornea in order to correct the refractive errors of the eye.

BRIEF SUMMARY OF THE INVENTION The present invention improves the prior art by providing an optical, diffractive LIC made of two different hydrogel materials that are biologically acceptable for long-term implantation in the cornea. The first material contains a diffractive surface and has a higher refractive index than the cornea. The second material is bonded to the first material to cover the diffractive surface and has a refractive index similar to the corneal tissue. The adequate permeability of the metabolites through the hydrogels of the diffractive .LIC produces a safe implant for the cornea. Therefore, an object of the present invention is to provide a safe and biocompatible intracorneal lens. Another objective of the present invention is to provide a safe and biocompatible intracorneal lens with a higher optical power. Yet another objective of the present invention is to provide a safe and biocompatible intracorneal lens that does not depend on the changes induced in the shape of the cornea to correct the refractive errors of the eye. Still another object of the present invention is to provide safe and biocompatible intracorneal lenses containing a diffractive surface.

Still another objective of the present invention is to provide safe and biocompatible intracorneal lenses that prevent inward cell growth and unacceptable deposits. These and other objects and advantages of the present invention will be apparent from the following detailed description and the following clauses.

BRIEF DESCRIPTION OF THE DRAWING The drawing is a cross-sectional view of the SCI of the present invention.

DETAILED DESCRIPTION OF THE INVENTION The LIC 10 of the present invention is designed to be implanted within a cornea and, generally, includes the base lens 14 having a diffractive surface 18, this is covered by the cover 16. The base lens 14 preferably It has a diameter of at least 5 millimeters.

The base lens 14 is preferably made of a material ("" MI ") having a water content in relatively high equilibrium at about body temperature, preferably 50% or greater, with a refractive index greater than the cornea tissue and preferably greater than 1.40. High water content helps to ensure the flow of glucose and other metabolites through the base lens 14. A MI material with high refractive index in combination with the diffractive surface 18 allows the SCI 10 to be processed relatively thin but still has its own refractive power Although it is desirable that the material used to make the base lens 14 have a water content and a refractive index as high as possible, the increase in the water content of any material with high refractive index necessarily The refractive index of this material will decrease due to the relatively low refractive index of water (1.336) .To effect the desired refractive change for the cornea while maintaining a thin lens in general (less than 150 micras being preferred and 50 micras at 100 micras being more preferred) the diffractive surface 18 is formed in the base lens 14. The diffractive surface 18 increases the power of the SCI 10 without increasing the overall thickness of the SCI 10. The construction of the diffractive surface 18 is well known in the art and is described in U.S. Patent Nos. 5,129,718 (Futhey, et al.), U.S. Patent Nos. 5,076,684 and 5,116,111 (Simpson, et al.), U.S. Patent Nos. 4,162,122, 4,210,391, 4,338,005, 4,340,283, 4,995,714, 4,995,715, 4,881,804, 4,881,805, 5,017,000, 5,054,905, 5,056,908, 5,120,120, 5,121,979, 5,121,980, 5,144,483, 5,117,306 (Cohen) and Patents US Nos. 4,637,697, 4,641,934 and 4,655,565 (Freeman), the total content of which is incorporated herein by reference. Those skilled in the art will understand that LIC 10 can be constructed to correct myopia, hyperopia, presbyopia and / or astigmatism using monofocal or multifocal diffractive optics and overlaying or combining refractive optics when necessary to correct astigmatism. It is possible to use any of a variety of hydrogel materials having the correct physical properties such as MI to form the base lens 14. The MI must have sufficient mechanical strength to allow bending or rolling of the SCI 10; MI must be photo-stable; and the preferred MI has already been proven safe in the industry of • contact lens and / or intraocular lenses. Suitable monomers for MI include aryl methacrylates, (et) arylalkyl acrylates, (et) acrylates of naphthyl, styrene, methylstyrene, N-vinylcarbazole, N, N-dimethylacrylamides, 2-phenylethyl methacrylate, 3-phenylpropyl methacrylate, 4-phenylbutyl methacrylate, 2-methacrylate phenoxyethyl, 3-phenoxypropyl methacrylate, 4-phenoxybutyl methacrylate, beta-naphthyl methacrylate, N-vinylcarbazole, N-vinylpyrrolidone, hydroxyethyl (meth) acrylates, polyethylene glycol (meth) acrylates, (meth) acrylates of polyethylene oxide, 3-methoxy-2-hydroxypropyl- (meth) acrylate, (meth) acrylic acid and dihydroxyalkyl (meth) acrylates. A preferred formulation for MI is: N-vinylpyrrolidone 69% 2-phenylethyl methacrylate 29% Allyl methacrylate (a crosslinker) 1% Lucirin TPO * (an initiator) 1% * diphenyl (2,4,6-trimethylbenzoyl) oxide Phosphine The MI material prepared according to this formulation has a refractive index between 1414 and 1416, a water content between 58% to 60% and a swelling factor of 1.34. The coating 16 is used to cover the diffractive surface 18 of the base lens 14 and to provide a smooth surface to prevent any cell interior growth and resultant opacification along the diffractive surface 18. To reduce the total thickness of the LIC 10, the coating 16 is preferably less than 20 microns thick. The material used to be the coating 16 (M2) preferably has a refractive index close to that of the cornea tissue and a water content in equilibrium at about the body temperature of at least 70%. The M2 must be addable to MI with similar swelling properties so as not to delaminate. The M2 should not form or crack during the rolling or bending of the LIC 10 and, preferably, should heal quickly (for example, in less than 3 minutes). The M2 must be photo-stable and preferably shown to be safe in the contact lens and / or infra-ocular lens industry. A preferred formulation for M2 is: Polyvinylpyrrolidone (PM-10K) (a plasticizer) - 19% Polyethylene glycol 200 (a plasticizer) - 29% Glyceryl methacrylate - 49% Ethylene glycol dimethacrylate (a crosslinker) - 0.5% Darocur 1173 * (an initiator) - 2.5% * 2-hydroxy-2-methyl-l-phenyl-propan-l-one The M2 prepared according to this formulation has a refractive index of 1.376, a water content of approximately 73% and a swelling factor of 1.30. LIC 10 is made using conventional molding techniques well known in the contact lens and intraocular lens art. See, for example, U.S. Patent No. 5,620,720 (Glic, et al.), The entire contents of which is incorporated herein by reference. A mold with a flexible bottom made of, for example, polypropylene, is filled with the material MI. A first upper mold made of, for example, fluoroethylene polypropylene (FEP), and with the base curve of the lens and the diffractive surface 18 is placed on the lower mold containing MI. MI is cured, for example, under blue light (450 nm) with a flow of 14-15 mW / cm2 for one hour.

Otherwise, MI can be cured by replacing Lucirin TPO with 1% t-butylperoxy (2-ethylhexanoate) the thermal initiator and thermally curing at 80 ° C for one hour followed by a post-cure period of one hour at 100 ° C. C. The first upper mold is removed and the material M2 is placed on the diffractive surface 18 of the newly formed base lens 14.

A second upper mold, also made from FEP and with the same base curve as the first upper mold but without diffractive surface 18 is placed on the lower mold. Pressure is applied to the upper mold (approximately 100 pounds / inch2) and the mold unit is exposed to ultraviolet light. { 366 nm) with a flow of 60-300mW / cm2 for 3 minutes. The second upper mold is then removed and the LIC 10 together with the lower mold is placed in heptane at 65-75 ° C for several hours to extract the unpolymerized monomers. The LIC 10 is removed from the lower mold, allowed to air dry for several minutes and hydrated for at least two hours in distilled, hot water. This description is given for purposes of illustration and exemplification. It will be apparent to those skilled in the art that changes and modifications can be made to the invention described above without departing from its spirit or scope.

Claims (20)

1. An intracorneal lens, consisting of: a) a base lens made from a first hydrogel material and with a refractive index greater than the refractive index of the cornea tissue; b) a diffractive surface formed on the base lens; and c) a coating covering the diffractive surface, the coating made of a second hydrogel material with a refractive index that is less than the refractive index of the first material.

2. The intracorneal lens of claim 1, wherein the first material has a refractive index of at least 1.4.

3. The intracorneal lens of claim 1, wherein the second material has a refractive index of about 1.37.

4. The intracorneal lens of claim 1, wherein the first material has a water content of at least 50%.

5. The intracorneal lens of claim 1, wherein the second material has a water content of at least 70%. The intracorneal lens of claim 2, wherein the first material has a water content of at least 50%. The intracorneal lens of claim 3, wherein the second material has a water content of at least 70%. The intracorneal lens of claim 1, wherein the first material consists of N-vinylpyrrolidone and 2-phenylethyl methacrylate. 9. The intracorneal lens of claim 1, wherein the second material consists of glyceryl methacrylate. The intracorneal lens of claim 1, wherein the base lens has a diameter of at least 5 millimeters. 11. The intracorneal lens of claim 1, wherein the base lens is a monofocal optic. 12. The intracorneal lens of claim 1, wherein the base lens is a multifocal optic. 13. An intracorneal lens, consisting of: a) a base lens made of a first hydrogel material and with a refractive index greater than 1.40; b) a diffractive surface formed on the base lens; and c) a coating covering the diffractive surface, the coating made of a second hydrogel material with a refractive index that is less than 1.40. The intracorneal lens of claim 13, wherein the first material has a water content of at least 50%. 15. The intracorneal lens of claim 13, wherein the second material has a water content of at least 70%. 1

6. The intracorneal lens of claim 13, wherein the first material consists of N-vinylpyrrolidone and 2-phenylethyl methacrylate. 1

7. The intracorneal lens of claim 13, wherein the second material consists of glyceryl methacrylate. 1

8. The intracorneal lens of claim 13, wherein the base lens has a diameter of at least 5 millimeters. 1

9. The intracorneal lens of claim 13, wherein the base lens is a monofocal optic. 20. The intracorneal lens of claim 13, wherein the base lens is a multifocal optic.