A contact lens that delivers medication gradually to the eye could improve outcomes for patients with conditions requiring treatment with eye drops, which are often imprecise and difficult to self-administer.

A team of researchers has shown that a novel contact lens-based system using a strategically placed drug polymer film to deliver medication gradually to the eye, is at least as effective (and possibly more so) as daily "latanoprost" eye drops in a pre-clinical model for glaucoma.

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Glaucoma is the leading cause of irreversible blindness in the world. While there is no cure for glaucoma, ocular medications aim to lower pressure in the eye with the goal of preventing vision loss.

Researchers designed a novel contact lens that contains a thin film of drug-encapsulated polymers in the periphery. The drug-polymer film slows the drug's release into the lens.

Because the drug film is on the periphery, the center of the lens remains clear. This feature allows for normal visual acuity, breathability and hydration. Lenses can be made with no refractive power or with the ability to correct the refractive error in nearsighted or farsighted eyes.

"Instead of taking a contact lens and allowing it to absorb a drug and release it quickly, our lens uses a polymer film to house the drug, and the film has a large ratio of surface area to volume, allowing the drug to release more slowly," said senior author Daniel S. Kohane, M.D., Ph.D., director of the Laboratory for Biomaterials and Drug Delivery at Boston Children's Hospital.

Contact lenses have been studied as a means of ocular drug delivery for nearly 50 years. Many such lenses are ineffective because they dispense the drug too quickly, however.

Reserchers designed the contact lens to allow for a more controlled drug release. They had previously shown in a 2014 study the lens is capable of delivering medication continuously for one month.

"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," said first author Joseph B. Ciolino, M.D., an ophthalmologist at Massachusetts Eye and Ear and an Assistant Professor of Ophthalmology at Harvard Medical School.

"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."

Currently, medications are delivered as eye drops, which sometimes cause stinging and burning, can be difficult to self-administer and are subsequently associated with poor patient compliance, with some studies suggesting that compliance is as low as 50 percent.

"This promising delivery system removes the burden of administration from the patient and ensures consistent delivery of medication to the eye, eliminating the ongoing concern of patient compliance with dosing," said Janet B. Serle, M.D., a glaucoma specialist at Icahn School of Medicine at Mount Sinai.

Tagscontact lens, drug polymer film, glaucoma, Daniel S. Kohane, Boston Children's Hospital