BOSTON, Aug. 29 (UPI) -- After 50 years of trying, researchers may have found an effective way to use contact lenses to deliver drugs for conditions treated with eye drops.
Glaucoma patients may soon be able to treat the condition using a lens that slowly releases medication to the eye, with some tests with monkeys suggesting the treatment method could be more effective than the standard eye drops, researchers at Harvard Medical School report in a new study.
The leading cause of irreversible blindness, glaucoma has no cure but doctors attempt to slow its development by prescribing drops for patients. The drops, however, often cause stinging and burning, and may be difficult for some patients to use, if they try to use them at all.
"If we can address the problem of compliance, we may help patients adhere to the therapy necessary to maintain vision in diseases like glaucoma, saving millions from preventable blindness," Dr. Joseph Ciolino, an ophthalmologist at Massachusetts Eye and Ear and an assistant professor at Harvard, said in a press release. "This study also raises the possibility that we may have an option for glaucoma that's more effective than what we have today."
Using a novel design, researchers created a contact lens with a thin film of drug-encapsulated polymers around its edges. The polymer film slows release of the drug -- previous attempts at a drug-eluting lens released medications far too fast -- while remaining on the side of the lens so its center remains clear for vision.
For the study, published in the journal Ophthalmology, researchers tested the lenses in four cynomolgus monkeys with glaucoma in one eye.
During the course of nine weeks, the researchers treated the monkeys with one week of wearing a low-dose contact lens, five days of latanoprost drops and one week of wearing a high-dose contact lens, with three weeks of no treatment between each type of drug delivery.
The low-dose contact lens, which contains lower doses of latanoprost than the eye drops, reduced pressure in the monkeys' eyes at about the same rate as the drops, and lenses with higher doses of the drug had higher pressure reduction than both the low-dose lens and the drops.
The researchers say studies to confirm results with the higher-dose lenses need to be conducted, and that they are also planning clinical trials to test the safety and efficacy of the lenses in humans.
"We found that a lower-dose contact lens delivered the same amount of pressure reduction as the latanoprost drops, and a higher-dose lens, interestingly enough, had better pressure reduction than the drops in our small study," Ciolino said. "Based on our preliminary data, the lenses have not only the potential to improve compliance for patients, but also the potential of providing better pressure reduction than the drops."
