Drug-dispensing contact lens passes early tests

A contact lens is shown in Somerville, Massachusetts June 10, 2008.

NEW YORK (Reuters Health) - A contact lens that gradually dispenses a steady stream of medication to the eye could ease treatment for glaucoma and other eye ailments if it advances through animal and human testing, according to new research.

For people who need eye drops for conditions such as glaucoma -- damage to the nerve that connects the eye to the brain -- using them several times a day is burdensome and inefficient. Due to natural blinking and tearing, typically only a little bit of the medication is absorbed by the eye. The drug-dispensing contact lens may boost convenience and effectiveness, say authors of the study.

Laboratory tests show that the drug-dispensing contact lens "can release really large amounts of drug for very long periods of time at a very steady rate," Dr. Daniel Kohane, director of the Laboratory for Biomaterials and Drug Delivery at Children's Hospital Boston, noted in a telephone interview with Reuters Health.

Kohane collaborated with Dr. Joseph Ciolino of the Massachusetts Eye and Ear Infirmary and colleagues at the Department of Chemical Engineering at the Massachusetts Institute of Technology to develop the drug-dispensing contact lens.

Although other groups have developed drug-releasing contact lenses, none have been able to achieve a constant, steady stream of medication at high enough levels to be therapeutic, the researchers note in the journal Investigative Ophthalmology and Visual Science. Prior contact lenses "have released very small amounts of drug for long periods of time or a lot of drug for not a long time," Kohane said.

In the lab tests, contact lens Kohane's team developed dispensed appropriate levels of ciprofloxacin -- an antibiotic used in eye drops -- for 30 days and in some tests for as long as 100 days. "We're talking really large levels of the drug, for example, enough antibiotic to still be effective for that long," Kohane said.

The drug-dispensing contact lenses are the size and thickness of commercially available contact lenses. The researchers have begun testing them in animals and hope to begin human testing soon.

Drug-dispensing contact lenses "could be used with almost any drug that could be applied to the eye, particularly the front of the eye, and for a range of conditions such as glaucoma, allergic conjunctivitis, dry eye, infections, pain, and things like that," Kohane noted.

SOURCE: Investigative Ophthalmology and Visual Science, July 2009.