AMNIOTIC OR PLACENTAL PREPARATION AND DEVICE FOR OPHTHALMIC USE AS DRESSING TO ENHANCE HEALING

Abstract

A biodegradable lens-shaped patch useful for healing and treatment of ocular conditions is disclosed. The patch is formed from a biodegradable carrier which carries amniotic extract and/or placental extract. The biodegradable carrier may be a collagen material. The lens-shaped patch may be shaped in the form of a conventional contact lens and s applied to a corneal surface to enhance healing of corneal injuries. After a certain period of time, the patch dissolves on its own and it need not be removed from the eye by a clinician. The degradation of the patch is controlled by the degree of cross-linking in the carrier material.

Claims

1-9. (canceled)

10. A lens-shaped patch that is applied to the cornea of an eye for the treatment of diseases and injuries to the cornea of an eye, comprising: a patch formed into the shape of a contact lens, wherein the lens-shaped patch is a uniform mixture of a biodegradable carrier material comprising collagen from a mammalian source and an active ingredient comprising an amniotic extract, a placental extract, or a combination thereof, wherein the lens-shaped patch has a convex exterior surface and a concave interior surface, wherein the interior surface of the lens-shaped patch conforms to the external surface of the cornea and the lens-shaped patch adheres to the cornea; wherein the collagen in the patch is cross-linked; wherein the lens-shaped patch dissolves while on the cornea; and wherein the lens-shaped patch does not contain a low water nonionic polymer, a high-water nonionic polymer, a low-water ionic polymer or a high-water ionic polymer.

11. The lens-shaped patch of claim 10, such that the active ingredient in the lens-shaped patch is in physical contact with the outer surface of the cornea.

12. The lens-shaped patch of claim 10, wherein the disease or injury to the eye is any of: dry eye syndrome, corneal trauma, corneal inflammation, corneal burn injury, or corneal ulcers.

13. The lens-shaped patch according to claim 10, wherein the patch is used to treat human or non-human mammal corneal diseases or injuries.

14-21. (canceled)

22. The lens-shaped patch of claim 10, wherein the patch has a controlled degradation time of between one day and thirty days adjusted by the use of cross-linking with riboflavin as a cross-linking agent in the lens-shaped patch.

23. (canceled)

24. The lens-shaped patch according to claim 10, wherein the patch further comprises a crosslinking additive.

25. The lens-shaped patch according to claim 10, wherein the patch further comprises riboflavin in an amount of 0.3% by weight.

26. The lens-shaped patch of claim 10, wherein the patch has a controlled degradation time wherein the rate of degradation is controlled by the degree of cross-linking, and the degree of cross-linking is controlled with UV irradiation of the lens-shaped patch.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIG. 1 is a side cross-sectional schematic view of a contact lens-shaped patch according to an embodiment of the invention.

[0017] FIG. 2 is a prospective side view of a contact lens-shaped patch according to an embodiment of the invention.

[0018] FIG. 3 is a side perspective view of a contact lens-shaped patch positioned for insertion on an ocular surface according to an embodiment of the invention.

[0019] FIG. 4 is a front schematic view of a lens-shaped patch where the biological curative active ingredient is confined to a peripheral ring.

[0020] FIG. 5 is a graph of mass changes over time for 0.1 mm thick lens-patches containing 15% and 30% placental extract, respectively, and 50:50 PLGA.

[0021] FIG. 6. Is a plot of the in vitro release of protein over 14 days from an inventive lens employing collagen as carrier.

DETAILED DESCRIPTION OF THE INVENTION

[0022] The term amniotic extract herein means any of various preparations derived from amniotic membrane materials, including preparations derived from amniotic membrane, amniotic stroma and amniotic jelly (e.g. membrane particles obtained or purified via a suitable extraction/purification process such as pulverization or homogenization). Placental extracts of any of various sources may be used in different embodiments of this invention. Placenta extract or placenta membrane may be derived from any of various mammalian sources, including human, sheep, or bovine. Sheep placental extract (SPE) is available commercially. For many uses, human placental extract may be less antigenic for use in humans. The term placental extract herein means any of various preparations derived from mammalian, including human, placenta (e.g. placental particles obtained or purified via a suitable extraction/purification process such as pulverization or homogenization). In this invention, amniotic extracts or placental extracts may be used alone or they may be blended. Any of amniotic extract or placental extract, or blend thereof, may be alternatively referred to as the active ingredient herein.

[0023] In an embodiment of this invention, the active ingredients are supported by or associated with a biodegradable carrier, filler or matrix. The biodegradable carrier active ingredient is formable into various shapes and configurations according to different embodiments of the invention. In an embodiment of the invention, the biodegradable carrier is formed into substantially the shape and size of a conventional contact lens. A patch formed by combining active ingredients with a synthetic or natural biodegradable and casting the same into the general shape of a conventional contact lens may be referred to as a lens-shaped patch or patch or lens patch herein. The biodegradable carriers provide structural support for the shape and structural integrity of the lens-shaped patch.

[0024] In an embodiment, a lens-shaped patch for treating diseases and injuries to the cornea is provided, including a biodegradable carrier material and an active ingredient comprising an amniotic extract and/or placental extract, wherein the biodegradable material and amniotic and/or placental extract are combined and formed into the general shape of a contact lens.

[0025] In an embodiment, the base curvature of the lens-shaped patch is similar to or slightly greater than the curvature of the cornea. As such, the inner surface of the patch substantially conforms to the external surface of the cornea and it adheres thereto allowing the patch to remain centered on the cornea.

[0026] In an embodiment of the invention, the inventive lens-shaped patch has a variable thickness and provides no magnification power or vision corrective properties. For example, the patch may have a thickness ranging between 0.040 mm and 0.20 mm and more preferably between 0.04 mm and 0.08 mm. In an embodiment, the lens is approximately 0.05 mm thick. The lens-shaped patch may be made in any of various diameters, preferably in the range of 14-24 mm. In order to conform to a medium-size cornea, the lens patch diameter is most preferably around 14 mm in diameter. The lens patch radius of curvature is within the range of 7.5-9 mm and most preferably a 7.8 mm radius of curvature. For example, FIG. 1 shows a side cross-sectional view of a lens-shaped patch having a diameter of 14 mm and a 7.8 mm radius of curvature. Lens-shaped patch 10 has a substantially convex outer surface 12 and a substantially concave interior surface 14. FIG. 2 shows a perspective view of the lens-shaped patch embodied in FIG. 1. FIG. 3 shows a lens-shaped patch 10 positioned to be inserted over the iris 16 of an eye 18, so that the lens-shaped patch is in physical contact with cornea 17 on the eye. Lens patch 10 is applied with its inner concave surface 14 contacting the cornea. As shown, the lens patch is appropriately sized and shaped to substantially cover the entire surface of the iris 16.

[0027] It will be understood by those of ordinary skill in the art that lens patches of other sizes may be molded to fit other eye geometries. In addition, where a numerical range is provided herein for any parameter, it is understood that all numerical subsets of that numerical range, and all the individual integer values contained therein, are provided as part of the invention.

[0028] For example, in an embodiment of this invention, a lens-shaped patch may be formed with a hole cut in the center of the lens to increase wearer visibility in that region. Alternatively, a small circular region of PLGA or collagen or other biodegradable polymer with no placental or amniotic extract may be placed in the center of the lens to increase wearer visibility. FIG. 4 shows a lens-shaped patch 20 having two regions, an outer peripheral ring region 22, and an inner central region 24. Outer peripheral ring 22 may contain active ingredients, whereas inner central region 24 may not. In one embodiment, inner central region 24 is a cutout. In another embodiment, inner central region 24 is carrier material (e.g. PLGA) without active ingredients. In either embodiment, the active ingredient is confined to the peripheral band 22.

[0029] In an embodiment, the diameter of lens patch 10 is around 14 mm. The diameter of inner central region may be anywhere between 4 mm to 10 mm that allows sufficient light to pass through for reasonable vision.

[0030] In use, the lens-shaped patch is applied to a corneal surface like a contact lens and it need not be implanted or supported by external structures like a supporting ring.

[0031] In an embodiment, the inventive lens-shaped patch need not be removed. Rather, it may be designed to dissolve in place on a cornea into small bio-acceptable components that may either by absorbed by the body or washed out with the eye's natural processes.

[0032] The lens-shaped patch may be translucent or transparent and may be composed of two primary ingredients to create a matrix or similar carrier for carrying curative biological extracts and provide curative ingredients to an ocular surface. The material used as a carrier or matrix may be any of various natural or synthetic biodegradable materials or blends thereof. For instance, in one embodiment of the invention, a lens-shaped patch is formed of placental extract powder that is embedded in or carried on a poly (DL-lactide co-glycolide) copolymer carrier (termed herein PLGA or PLDG). The PLGA copolymer acts as a biodegradable carrier for the active ingredients.

[0033] In an embodiment of the invention, a poly(DL-lactide co-glycolide) copolymer is used as a biodegradable structural carrier material for the lens-shaped patch. Poly(DL-lactide co-glycolide) copolymer is an ester-terminated copolymer of lactide and glycolic acid (PLGA). In an embodiment, the ratio of lactide to glycolic acid is 50:50. Poly(DL-lactide co-glycolide) copolymers with different lactide toglycolide ratios may be used in different embodiments of the invention. Moreover, any of various biodegradable polymers may be used as an alternative to PLGA. For example, poly(DL-lactide-co-caprolactone), methoxy (polyethylene glycol)-b-poly(L-lactide), polylactide, polyglycolide, and other biodegradable polymers known in the art may be used in embodiments of the invention.

[0034] PLGA is commercially available, for example, via LACTEL Absorbable Polymers, Birmingham, Ala. PLGA has been used in medical devices, primarily as sutures or cell growth scaffolds. It should be noted that 50:50 PLGA described above provides an excellent balance of the following material qualities: mechanical modulus at 22 C., mechanical modulus at 37 C., <1 month degradation rate at 37 C. in phosphate buffer, optical transparency, high solubility in common organic solvents, and overall material quality.

[0035] In addition to, or as an alternative to, synthetic carriers, natural biodegradable carrier materials may be used in different embodiments of the invention. For example, collagen obtained from any of various mammalian sources may be utilized in embodiments of the invention as a biodegradable structural material carrier. In an embodiment, collagen from a bovine flexor tendon is employed, which is commercially available. Collagen as the advantages of superior transparency as compared to PLGA polymers, and better oxygen permeability and higher water content. High water content is desirable in this invention and will cause high water transmission and high oxygen permeability.

[0036] The active ingredients may be bleached and finely ground to render them transparent or translucent. For example, placental extract may be bleached with a suitable solution, such as a solution of approximately 10% aqueous hydrogen peroxide for a period of about 24 hours. Thereafter, the water is removed (e.g. via freeze drying, vacuum drying, air drying), and the resultant placental extract is ground to a powder preferably with a particle size of less than 5 microns, or more preferably a particle size of less than 1.0 microns, or less than 0.1 microns. The degree of transparency or translucency may depend on several factors, including the degree of bleaching of extract powder and the particle size.

[0037] Plasticizers and other additives and/or active ingredients may be added in different embodiments of the invention. For example, plasticizers such as triethyl citrate, tributyl acetylacetate, glycerol, or the like may be added.

[0038] In an embodiment of the invention, a lens-shaped patch is formed of approximately 90% PLGA by weight and approximately 10% active ingredients by weight. In another preferred embodiment of the invention, the patch is formed of approximately 80% PLGA by weight and approximately 20% active ingredients by weight. Any of various plasticizers may be added in the range of 1-20% by weight.

[0039] The following are non-exhaustive possible ranges of respective biodegradable carrier, active ingredient and plasticizer: [0040] 10-30% bleached, dried active ingredient, micronized to a particle size of about 5 microns to less than 1.0 microns; [0041] 50-90% 50:50 poly(DL-lactide co-glycolide) block copolymer (PLGA) or other biodegradable polymer(s); [0042] 0-20% other additives such as plasticizers, other active ingredients, etc.

[0043] In other embodiments of the invention, active ingredients may comprise as much as 50% of the lens-shaped patch by weight. In another embodiment, the biodegradable carrier may comprise more than 90% of the lens-shaped patch by weight. The following are non-limiting examples of such ranges: [0044] 1-50% bleached, dried active ingredients, micronized to a particle size of about 5 microns to less than 1.0 microns; [0045] 20-99% 50:50 poly(DL-lactide co-glycolide) copolymer (PLGA) or other biodegradable polymer(s); [0046] 0-30% other additives such as plasticizers, other active ingredients, etc.

[0047] In one embodiment of the invention, the constituents of the lens-shaped patch (e.g. biodegradable polymer, active ingredient and any additives) are associated in a matrix or mixture with no covalent bonding or cross-linking of molecules. In this embodiment, the active ingredient is not chemically bound to the carrier material, active ingredient is not chemically bound to active ingredient, and carrier material is not chemically bound to carrier material.

Controlled Biodegradability

[0048] Depending on the nature of the ocular condition being treated, the treatment time will vary from a few days to several weeks. These treatment durations are determined by experienced clinicians.

[0049] Accordingly, the lens-shaped patches provided herein may be designed to degrade over a specified timeframe. That is, different lens patches may be specifically calibrated to degrade at pre-determined times, ranging from days to several weeks. The degradation time may be as short as one day and extend up to 30 days. In embodiments of this invention, the inventive lens-shaped patches completely dissolve and need not be removed after application. A specific degradation time may be selected, for example, by varying any of the following: the dissolvable polymer, the ratio of polymer to active ingredient, the plasticizer concentration and type, the thickness of lens patches or a combination of the foregoing. Alternatively or additionally, chemical curing processes may be performed, such as, crosslinking by gamma or e-beam sterilization, or a adding a chemical crosslinker.

[0050] The term degradation (or biodegradation) as used herein means the loss of mechanical integrity of the lens-shape patch, followed by the degraded material breaking into small portions that can either be absorbed by the body or slough off the eye in the form of tears.

[0051] An embodiment of a degradable matrix or carrier material for this invention employs poly(DL-lactide-co-glycolide). It has been demonstrated that in 37 C. phosphate buffer, a PLGA film containing 0-30% sheep placental extract (PE) and having a thickness of 0.1 mm exhibited significant softening after approximately 18 days. By 25 days, these same films had broken into fragments and with some mechanical action were easily decomposed. Thus, lens patches of 0.1 mm in thickness should degrade in the eye at 18-25 days. For example, FIG. 5 shows a graph illustrating mass changes over time for 0.1 mm thick lens-patches containing 15% and 30% placental extract, respectively, and 50:50 PLGA. As shown, the mass decreases slightly over the first week, as the PE is leached out of the film and into the buffer solution. The mass then increases with time as the PLGA matrix swells with water as part of the degradation process. Note that this behavior may be modified for other mixtures of biodegradable polymer with the extract.

[0052] The 50:50 PLGA copolymer is known to degrade faster than other copolymers or homopolymers of lactide and glycolide. Water can diffuse through the matrix, and the PLGA degrades by the action of hydrolysis on the esters in the lactide/glycolide chains. This hydrolysis occurs much faster at 37 C. than at 22 C.

[0053] Another embodiment of this invention uses collagen as a carrier material.(9) In an embodiment, a form of collagen that is amenable to forming transparent membranes may be used. An embodiment of such a collagen is bovine flexor tendon collagen.(10) This form of collagen is supplied as a powder that can be dissolved in cold water at pH 2-3, and then blended with additional materials. The collagen can be poured into molds and gelled at 5 C. over several hours to give transparent products that are resorbable when applied onto living tissue. The rate of degradability of collagenous matrices can be controlled by the degree of cross-linking. The more highly cross-linked the material, the slower the degradation. The cross-linking can be a factor of the collagen itself, depending on the tissue source and chemical features of the extraction, or it can be adjusted by the use of an additive such as riboflavin and then UV irradiation, which cross-links the collagen stands and retards the biodegradation. The degradation time can be adjusted to as long as 30 days.

[0054] PLGA matrices have the advantages of scalability, controlled biodegradability based on resin selection, and a proven history of use as implants. However, PLGA may be less transparent and have higher haze, and lower oxygen permeability compared to embodiments with a collagen matrix. PLGA may also be more brittle than collagen lens patches. By contrast collagen carrier materials may have greater transparency than PLGA matrices, collagen may have superior oxygen permeability and a higher water capacity than PLGA, which are both desirable features.

Thickness

[0055] With thinner layers of the PLGA or collagen-based films, the overall degradation rate should be slightly faster since there is more surface area exposed to the 37 degrees C. water and because mechanical failure (tearing through the thickness) will occur more quickly. However, degradation does not necessarily scale 1:1 with thickness because water can saturate into the PLGA within hours of exposure. As stated, the biodegradation rate of a 0.1 mm PLGA patch lens is approximately 18-25 days. A lens patch of approximately 0.05 mm thickness will degrade in approximately 14-21 days. Thus, extending or reducing the degradation period may be achieved by respectively increasing or decreasing the patch lens thickness.

Active Ingredient Content

[0056] Control of degradation rates may also be affected by altering the concentration of active ingredients. For example, in a lens-shaped patch where amniotic and/or placental extract contents are below 40% by weight (40% by volume), most active ingredient particles will be dispersed and isolated within the biodegradable matrix. In this situation, the degradation rate will be slightly decreased as the active ingredient level goes from 0-40%, since the dissolution of active ingredients into the surrounding water-based region will lead to cavities in the PLGA matrix which will slightly increase degradation rates. However, this acceleration in degradation rate will be small, since the PLGA matrix will remain continuous.

[0057] For active ingredient contents above 50% by weight (50% by volume), the active ingredient particles will start to bridge the PLGA matrix, and dissolution of the PE particles will lead to the PLGA matrix to rapidly break down. It may be expected that if 50% or greater PE particles are added, degradation rates of the PE-PLGA film will be very fast, on the order of <1 week.

[0058] i. Plasticizer Content:

[0059] Yet another method mechanism of altering degradation rates is through the use of plasticizers. That is, when plasticizers such as triethyl citrate, tributyl acetylacetate, glycerol, etc. are added to the PLGA/active ingredient matrix, the degradation could be significantly accelerated. For example, the 50:50 PLGA has a glass transition temperature of 45-50 C. [LACTEL product literature], which is still above the 37 C. use temperature. Addition of a plasticizer will suppress the glass transition temperature to close to or below 37 C., leading to the PLGA being significantly softened and a much faster degradation time. With plasticizer at 1-20% by weight, a 0.1 mm thick PLGA film will degrade at 37 C. in phosphate buffer in 1-7 days. Thus, adding varying concentrations of plasticizers will accordingly allow for producing lens patches of varying degradation rates.

[0060] ii. Crosslinking

[0061] Many biomedical polymers are sterilized with gamma radiation or e-beam sterilization techniques. In addition to preventing future microbial or viral growth, this sterilization has the effect of partially crosslinking the polymer. This method may be used on the PLGA/active ingredient matrix described herein in order to decrease the rate of degradation. That is, crosslinking by gamma or e-beam will make the PLGA material more resistant to degradation and, as such, it may be extend the degradation time by up to 2-3 times depending on the total radiation level imposed by the gamma radiation or e-beam exposure. However, the dosage of gamma radiation or e-beam used for this purpose must be adjusted to maintain the biological activity of the active ingredients.

[0062] Additionally or alternatively, a chemical crosslinker could be used in a similar fashion. There are many biologically compatible, bi- and tri-functional chemical crosslinkers that are commercially available. These may include organic molecules terminated with azides, amines, bromides, maleimides, isocyanates, sulfides, and esters.

[0063] It will be understood by those of ordinary skill in the art that other additives and active ingredients may be used in different embodiments of the invention. For example, bioactive ingredients (pharmaceuticals or natural ingredients) that are known in the art to assist with healing and limit irritation may be included in addition to the placental or amniotic active ingredients. Biocompatible dyes may also be added to increase the visibility of the lens when being handled, prior to insertion in the eye. Finally, other biocompatible polymers that have a different biodegradation rate than the primary biocompatible polymer may be added.

[0064] In one embodiment of the invention, placental extract is encapsulated in biodegradable polymer microcapsules (made of similar biodegradable polymer as discussed above), and then incorporated into an alternate polymer matrix. For example, these microcapsules could be placed in a traditional contact lens hydrogel and the release of placental extract would be dependent on biodegradation of the microcapsule walls, rather than biodegradation of the full bandage lens.

[0065] It will be understood that the patch lens may be formed of different thicknesses and/or geometries in different embodiments of the invention. For example, lenses may be between 0.02 mm and 0.2 mm thick.

[0066] In some embodiments of the invention, the lens may incorporate varying thickness to provide a magnification power. Additionally, the lens radius of curvature may be changed to provide more or less centering force on the underlying cornea. The lens diameter may also be varied to fit different corneal sizes or to cover more of the sclera.

[0067] The inventive lens-shaped patches may be used to maintain the ocular surface health and to promote healing after injury due to inflammation, infection, trauma or surgery. Because the patch contains naturally active ingredients, and it degrades into bio-absorbable molecules, it is an ideal alternative to bandage contact lenses for protecting the eye.

[0068] Inventive lens-shaped patches also may be designed as a drug delivery system. For example, the lens patch may be impregnated or otherwise provided with drugs such as antibiotics, vitamins or other medicines that are to be applied to the eye. The drugs, as such, are delivered directly to a site where they are needed. As mentioned above, the timing of drug delivery may be manipulated by choosing a patch having a desired degradation rate.

Therapeutic Utility

[0069] The amniotic extract and placental extracts employed in this invention reduce inflammation, reduce fibrovascular ingrowth, and facilitate epithelialization. These activities will have a healing effect for diseases and injuries to the cornea. This invention provides a method of treating an ocular condition, including providing a lens-shaped patch formed of biodegradable carrier material and an active ingredient comprising an amniotic extract and/or placental extract, where the lens-shaped patch has a substantially convex exterior surface and a substantially concave interior surface. The lens-shaped patch is applied to a patient's cornea, so that the interior surface of the lens-shaped patch contacts the cornea. The lens-shaped patch may be allowed to dissolve while on the patient's cornea.

[0070] The inventive lens-shaped patch may be used to therapeutically treat damaged or diseased cornea, limbus and surrounding conjunctiva, in addition to other wounds and conditions. For example, the patch may be used to promote healing after injury due to inflammation, infection, trauma or surgery and/or to treat dry eye or other ocular conditions. Any treatment and/or benefit imparted to a patient's cornea, limbus and/or surrounding conjunctiva is alternatively termed treatment of an ocular condition herein.

[0071] The following are non-limiting examples of methods of ocular treatment using the inventive lens-shaped patch:

Treatment of Dry Eye Syndrome

[0072] The inventive lens-shaped patch may be inserted into a patient's eye to treat ocular surface disorders associated with dry eye condition. With the patch so fitted in the eye, it will provide protection and enhance healing of ocular surface. Depending on the desired treatment duration, the patch will dissolve over time and eventually liquefy to provide additional lubrication to the healed ocular surface. The use of the lens-shaped patch may be repeated as needed to protect and maintain ocular surface health. This will provide a sustained level of treatment and may positively impact the quality of life.

Treatment of Ocular Surface Trauma Caused by Chemical or Thermal Injury (Burns)

[0073] The inventive lens-shaped patch has the potential to enhance healing of the damaged ocular surface. After copious irrigation of the injured surface and removing of any residual chemical particles, the patch will be applied to the ocular surface as a bandage contact lens. Other conventional treatment can be applied while the patch in place. And the size of the patch can be changed depends on the affected surface area. Multiple applications of a rapidly degraded lens can be applied during the acute phase. Slower degrading lens-shaped patches can be used thereafter. As the acute phase of this condition is extremely short, early intervention usually decreases the risk of blindness.

Treatment of Non-Healing Corneal Ulceration

[0074] The lens-shaped patch may be inserted into a patient's eye to as an adjunct in treating superficial corneal ulcers secondary to trauma, infection, disease of after surgery. Treatment of the underlying cause is recommended.

Post-Refractive Treatment

[0075] Postoperative complications after refractive surgery include pain, epithelial defect, and/or haze. The inventive lens patch may present an effective solution to solve these critical problems when inserted post photorefractive keratectomy (PRK).

[0076] The inventive method further includes the steps of determining a timeframe required for proper healing and/or treatment of an ocular condition (heal rate) and selecting a lens-shaped patch that has an expected degradation timeframe (degradation rate) that is the same as or greater than the expected heal rate. Once the determination of a heal rate is made, a clinician inserts a lens patch having a matching degradation rate or a patch having a degradation rate that is greater than the heal rate into the eye of a patient. The patient is then free to go home wearing the patch, which will dissolve on its own, potential averting the need to return to the doctor for removal, and also dispensing with the need for maintaining rings required in prior art systems.

[0077] The inventive device and method is also of utility for treating corneal injuries to non-human mammals, including pets and livestock. For example, the method can be used to treat ocular injuries and ocular diseases in dogs, cats, horses, cattle, sheep, pigs, etc.

EXAMPLES

[0078] In embodiments of the invention, the inventive lens patches are formed as described below.

Example 1. Sheep Placental Extract-PLGA Lens-Shaped Patch

[0079] PLGA is dissolved in a suitable solvent (e.g. a blend of 95% acetone and 5% N,N-dimethylacetamide), and bleached sheep placental extract (SPE) (20% by weight compared to the PLGA) is added to this mixture and it is wet ball milled until the mixture is transparent. This mixture is then cast onto a smooth, low energy surface (e.g., Teflon-coated glass) to produce a film of PLGA+SPE with a dry film thickness of 0.040-0.050 mm. The film is then carefully dried, first under room temperature air, and then under vacuum, until it is stiff and durable. The film is then thermoformed at 70 C. into the bandage lens-shaped patch and demolded at 0 C. A concave or convex thermoforming mold may be used. After thermoforming, the bandage lens is trimmed or punched to the appropriate diameter. This solvent casting and molding process leads to a highly uniform, high optical transparency product.

[0080] In another embodiment, patch lenses may be produced by compounding the SPE powder and PLGA at elevated temperatures, followed by hot pressing sheets, and finally, followed by thermoforming to lens shapes. Alternatively, extract powder and PLGA are compounded at elevated temperatures, followed by compression molding to lens shapes. In another alternative, extract powder and PLGA are injection molded at elevated temperatures into a lens cavity.

Example 2. Bovine Collagen-SPE Lens Shaped Patch

[0081] A patch comprising 72.7% bovine flexor tendon collagen, 22% water, 5% SPE, and 0.3% riboflavin, was formed by first homogenizing and dissolving lyophilized collagen into a viscous mostly clear suspension in cold 1% acetic acid. The collagen was concentrated to 4% solids (by weight in the solution) at 40-50 C. under vacuum, and filtered through a 25 m polypropylene filter. SPE was homogenized in water at pH 9.0 with 0.1% poloxamer 407 (a hydrophilic nonionic surfactant), filtered subsequently through 25 m, 1 m and 0.2 m hydrophilic filters. The SPE content was assayed at about 4.5% solids by thermogravimetric analysis as brownish, clear liquid. Protein content was separately verified to be 2.4% per a Pierce BCA protein assay.

[0082] The collagen mixture, SPE mixture, and riboflavin were blended together in a ratio of 100:33:0.2 solids content, the pH was adjusted as needed, and the mixture was poured into two-sided polypropylene molds and refrigerated at 5 C. until gelled, approximately 1 hour, One side of the mold was removed, and the patches were then dried at room temperature for 24 hours. The water content of these patches was approximately 22% as measured by thermogravimetric analysis. The patches were irradiated under a low intensity UV-A lamp for 30 minutes to cross-link the collagen and riboflavin.

[0083] FIG. 6 shows a plot of protein release from the inventive lens of this example. Fourier Transform Infrared Spectroscopy (FTIR) was performed on dried solids from sheep placenta extract solution. Pierce BCA Protein Assay was performed on sheep placenta extract solution. Original liquid (4.5% solids) was determined to contain 2.4% protein. Based on batch sheets for lens fabrication, each 0.1 mm thick 8.4 mm15 mm lens (total mass 29 mg) is calculated to contain 0.81 mg sheep placenta protein and 27.5 mg collagen (which is itself mostly protein). Protein assay over 14 days is plotted in FIG. 6, and shows significant release of protein into solution on day 1, followed by a plateau as time approaches 14 days in PBS buffer at 37 C. There was significant release of protein into solution on day 1, followed by a plateau as time approaches 14 days. At 14 days, 15.7 mg of protein was released from a lens (n=3, average of all data points). Since this exceeds the original quantity of 0.81 mg of SPE, these results suggest that both sheep placenta and collagen protein has been released into the buffer solution. The lens was not completely dissolved at 14 days, suggesting that in clinical practice, this lens would continue to provide a protective and therapeutic effect even at the 14 day point.

[0084] The patch of this example has a water content of 22% when dried and ready for use. In vitro, this lens had a water content of 77% when soaked in phosphate buffered saline for 1 hour, and 66% when soaked in phosphate buffered saline for 24 hours.

[0085] For storage, this lens can be frozen or dried to <10% water content.

[0086] It should be understood that the preferred embodiment was described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly legally and equitably entitled.

REFERENCES

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