Joanna Cosgrove06.14.10
Consumers turn to vitamin E to treat a variety of internal and external conditions. Now researchers have developed a new and novel use for it—vitamin E impregnated contact lenses—as a weapon in the fight against glaucoma, a leading cause of blindness that stems from optic nerve damage.
In a presentation at a meeting of the American Chemical Society, head researcher Anuj Chauhan, PhD, an associate professor at the University of Florida, explained to attendees that nanosized aggregates of vitamin E, when loaded onto specially medicated contact lenses, can help extend the duration of glaucoma medicine released onto the eye almost 100 times longer than possible with current commercial lenses.
Eye drops that relieve the abnormal build-up of pressure inside the eye that occurs in glaucoma, are a mainstay treatment, however tears can carry the drug away within about two to five minutes of putting drops in the eye without the medicine even reaching the targeted tissue. “Traditional methods such as eye drops lead to drug wastage, potential side effects, low compliance and burst delivery of drug,” he said. “This approach will ensure that drug is delivered at a slow rate for extended periods leading to less wastage and side effects, and higher compliance.
“Much of the medicine gets absorbed into the bloodstream, which carries it throughout the body where it could cause side effects,” he added. “Only about one to five percent of drugs in eye drops actually reach the cornea of the eye.”
The extended-release delivery lens with vitamin E developed by Dr. Chauhan and his colleagues hinges on invisible clusters, or aggregates, of vitamin E molecules that form what Chauhan describes as “transport barriers” that slow down the elusion of the glaucoma medication from the lens into the eye. The drug released from the lens into the eye stays in the tears far longer than the two to five minutes with eye drops, leading to more effective therapy.
Dr. Chauhan described the vitamin structures as beneficial “nanobricks.” “The drug molecules can’t go through the vitamin E. They must go around it,” he said. “Because the nanobricks are so much bigger than the drug molecules—we believe about a few hundred times bigger—the molecules get diverted and must travel a longer path. This increases the duration of the drug release from the lenses.”
Another benefit of vitamin E incorporation is that vitamin E is known to be an antioxidant, whose slow release from lenses could also help in prevention of ophthalmic diseases like cataract and glaucoma.
Furthermore, vitamin E blocks UV radiation, leading to reduced ocular damage from the UV light. “Our research has shown that vitamin E can be loaded into the lenses without any reduction in transparency,” he said. “The drug release durations from vitamin E loaded lenses are about 100 times longer than from commercial lenses for several ophthalmic drugs, including the glaucoma drug timolol, the anti-inflammatory drug dexamethasone, and the anti-viral drug flucanozole. Thus, vitamin E loaded lenses could be highly effective in synergistic prevention and treatment of ophthalmic diseases through extended delivery of the desired drugs and the nutraceutical vitamin E.”
Dr. Chauhan said that about 20% vitamin E by weight must be infused into the lens in order to deliver the observed benefit, and the lenses are completely transparent even with vitamin E loadings as high as 70%.
He said the lenses could be designed for continuous wear for up to a month, and in addition to treating glaucoma, the contacts could help other eye conditions, such as cataract and dry eye.
“Vitamin E is a proven nutraceutical that in small amounts is good for the eye because of its antioxidant properties,” he said. “Also, vitamin E presence in the contact lenses blocks UV radiation, leading to increased protection against the UV light. We believe it could be helpful in disease treatment and in prevention as well.”
Dr. Chauhan said animal studies in beagle dogs are ongoing to explore glaucoma treatment through vitamin E laden contact lenses. He also said that clinical trials of the new lenses could begin within a year to two years, with possible commercialization in about five years.
