What's New in the Future of the Science of Sight? Medicated Contact Lenses to Treat Glaucoma
According to the American Optometric Association, the second leading cause of blindness in the U.S. is glaucoma (cataracts are the leading cause), the term for a group of eye disorders that, over time, destroy the optic nerve. The most common type is called primary open-angle glaucoma. Its onset is gradual, and like an invisible enemy, it invades quietly, building up fluid pressure that damages the fibers of the optic nerve. The initial glaucoma symptom, peripheral (side vision) impairment, arises after the irreversible damage has been done. Left untreated, lost side vision can advance to lost central vision and then to blindness. Everyone over 60 is at risk for glaucoma, especially Mexican-Americans, people with a family history of glaucoma, and African-Americans as early as age 40.
When glaucoma is diagnosed, the standard of care is one or more medications, in the form of eye drops, to prevent further damage. The medications reduce fluid volume in the eye to lower the pressure on the optic nerve. Most of us have used eye drops at some point in life and discovered that they are not user-friendly. Fortunately, at this link, the Glaucoma Research Foundation offers illustrated instructions for using eye drops. For instance, a drop is 0.05 mL, but how much pressure on the small eye drop bottle yields that amount? Why does a well-executed squeeze produce nothing, and then a blink seems to draw a “geyser” of drops to the eyelid? Add to that the painful reality that glaucoma eye drops often cause stinging and burning, the challenges associated with eye drops are thus a medication adherence barrier for many people with glaucoma.
Enter (drum roll, please) the medicated contact lens, which clinical researchers have been refining for five decades. It hasn’t yet received Food and Drug Administration (FDA) approval, but the technology is now one step closer to clinical trials to receive that approval. The last hurdle was finding a way to control the amount of medication released from a contact lens. Kudos to the research team at Massachusetts Eye and Ear, who tested the delivery of glaucoma medication by encasing it in a special film on the periphery of the lens to prevent interference with vision. The experimental film succeeded in providing controlled release of the medication. Interestingly, in tests done on monkeys with glaucoma, lower-than-standard doses of medication via the lenses provided the same amount of pressure reduction as the eye drops at the standard dose. A higher-than-standard dose via the lenses caused even better pressure reduction than the eye drops at the standard dose.
What does this exciting news mean for people with glaucoma? The higher-dose lenses are undergoing further study to confirm results, and the research team is preparing study protocols for clinical trials to establish safety and efficacy in people. In two or more years, pending safety and efficacy results from early clinical trials, the lenses may be accessible to participants in much larger and more geographically widespread studies. Ultimately, following FDA approval after successful clinical trials, manufacturers could make medicated contact lenses with and without corrective refraction. That way they could be used by many more people with glaucoma to save their sight with as few barriers as possible.