Drug-dispensing contact lens may help glaucoma patients

Scientists have developed new contact lenses that deliver medication gradually to the eye, an advance that may replace eye drops that are difficult to administer and also improve outcomes for patients who have glaucoma - the leading cause of irreversible blindness.
Researchers showed that the novel contact lens, which uses strategically placed drug polymer film to deliver medication gradually to the eye, is possibly more effective than daily latanoprost eye drops in a pre-clinical model for glaucoma.
"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 Joseph B Ciolino, from the Harvard Medical School in the US.

"The lenses have not only the potential to improve compliance for patients, but also the potential of providing better pressure reduction than the drops," said Ciolino.
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.
Currently, the 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 per cent.

"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, from the Icahn School of Medicine at Mount Sinai.

Contact lenses have been studied as a means of ocular drug delivery for nearly 50 years, yet many such lenses are ineffective because they dispense the drug too quickly.
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 coming out of the lens.

The 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 Daniel S Kohane, from the Boston Children's Hospital.
The effect of this drug eluting contact lens was assessed in four glaucomatous monkeys.
The researchers showed that the contact lens with lower doses of latanoprost delivers the same amount of eye pressure reduction as the eye drop version of the medication.

The lenses delivering higher doses of latanoprost had better pressure reduction than the drops.
The study was published in the journal Ophthalmology.