Collagen Corneal Shields
The collagen corneal shield is a newly developed, potentially multipurpose ophthalmic lens, which is made of a natural protein. Collagen, in humans, is one of the most widespread and important proteins found in the body. It is an essential component of joints, skin, and the surface of the eye. Collagen is the major component of the white sclera and the clear cornea, both of which make up the outer coat of the eyeball. Additionally, collagen is an essential element for healing wounds anywhere in the body, including the eye.
Since collagen is a natural, widely available protein involved in the support and protection of vital structures, many researchers have tried to use extraneous collagen to protect the surface of the eye in a variety of disease states. The pioneer in this research is Dr. Svyatoslav Fyodorov of the Soviet Union. Dr. Fyodorov was able to extract collagen from porcine sclera and shape it in the form of a contact lens that can easily be placed on the surface of the eye. Early experience with his collagen “contact lens” showed that it was able to protect the ocular surface and also that it was dissolvable. It seemed that naturally occurring enzymes in the tear film caused the collagen contact lens to dissolve over a period of time.
Bausch & Lomb Pharmaceuticals, a division of Bausch & Lomb, Inc. (an international contact lens and ophthalmic care company) acquired the rights to develop and market these collagen contact lenses, now known as BioCora collagen shields. After much research, Bausch & Lomb has been able to produce the shields in a reproducible manner and in a variety of shapes and thickness. Additionally, of great significance, Bausch & Lomb has been able to slightly alter the biochemical composition of the shields and thereby vary their dissolution rate. Shields have now been produced to dissolve in 6, 12, 24, 48, and 72 hours and even one week.
What are the practical uses of collagen shields?
The most obvious use is for ocular surface lubrication. Again, collagen is a naturally occurring protein that is totally safe for use on and in the body. As these shields dissolve, they become gel-like and eventually liquefy. Early studies have demonstrated that this gel-like dissolution can be very helpful to individuals who do not produce sufficient quantities of tears. (This “dry eye” condition can be quite damaging to the ocular surface.) These patients are often required to place drops of artificial tears into their eyes every 30 or 60 minutes. Early research has shown that the collagen shield can reduce the necessity for this frequent and inconvenient administration of artificial tears. The bioCor collagen shield is currently available to physicians for use among patients with dry eye syndromes.
Other potential uses for the collagen shields are being actively investigated by Bausch & Lomb Pharmaceuticals as well as by several research organizations around the country, including the UIC Eye Center. One of the most exciting areas that has stemmed from these investigations is drug delivery. The collagen shield, it has been found, can serve as a “sponge” to collect medications that are placed in drop form on the surface of the eye and then slowly release them over a period of time as the shield dissolves. A number of laboratory and clinical studies are beginning to show that the drug concentrations released from the collagen shield are high enough to be effectively used in treating a variety of diseases (including infections and inflammation of the ocular surface.) This “time release” of topical medications to the eye has obvious benefits for use in the several potentially blinding diseases that require frequent administration of drop medications. The potential for an ophthalmologist to place a shield with a drug on the surface of a patient’s eye, as opposed to asking the patient to place frequent drops on the eye over long periods of time, is a revolutionary concept. Collagen shields have not yet been formally approved by the Food and Drug Administration for this use.
However, clinical studies have begun or will soon begin to investigate the usefulness and safety of collagen shields for the delivery of medications in several centers around the country, including the UIC Eye Center.
Another potential use for the collagen shields is that of ocular surface protection. In nearly all types of eye surgery, the surface coat (the sclera or the cornea) must be incised to allow access to the interior part of the eye. How this incision heals is of crucial importance to the success of the surgery. A basic necessity for successful healing of either surgical incisions or wounds created by trauma is that the wound must be adequately protected from the external environment as well as from the blinking action of the eyelids. This is why patients who have eye surgery or who have had trauma to the eyes are required to wear a patch in the early phases of healing. In addition to patching therapy, ophthalmologists have used special soft contact lenses (called “bandage” contact lenses) to provide protection to the surface of the eye. These bandage contact lenses are expensive and have been associated with some complications, particularly when they are used over a long period of time. As the collagen shield contains a naturally occurring protein, it would appear to be an ideal alternative to bandage contact lenses for protecting the eye. This area of research is in its infancy and is being conducted primarily here at the UIC Eye Center. Preliminary results have shown that the collagen shield can indeed provide an adequate protective environment to allow healing of surgical and traumatic wounds to the eye.
Another intriguing possibility that we are actively researching at the UIC Eye Center is whether the nature of the shield itself could improve wound bearing. As noted earlier, collagen is an essential part of the natural wound healing process. It is conceivable that the collagen in the shield could be incorporated (as the shield dissolves) into a healing wound on the surface of the eye and have beneficial effects.
The future for collagen shields is highly promising. The characteristics of providing ocular lubrication, protection, and drug delivery and the potential for better and faster wound healing may eventually make these shields a standard part of ophthalmic practice.
The UIC Eye Center is playing an important role in the determination of the effectiveness and safety of BioCor collagen shields in a variety of eye diseases. With the help of Bausch & Lomb Pharmaceuticals, a corneal research laboratory has been created in the Eye and Ear Infirmary of the UIC Eye Center to investigate the wound healing and drug delivery aspects of these shields.