Polymer contact lens better delivers controlled doses of ocular medications
A team of researchers at Massachusetts Eye and Ear (a Harvard Medical School Teaching Hospital) and Boston Children's Hospital (both in Boston, MA) has designed a contact lens that delivers medication gradually to the eye, which could improve outcomes for patients with conditions requiring treatment with eye drops, which are often imprecise and difficult to self-administer. The lens, which uses a strategically placed drug polymer film to deliver medication gradually to the eye, is possibly more effective than daily latanoprost eye drops in a preclinical model for glaucoma (the leading cause of irreversible blindness in the world).
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"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," says Joseph B. Ciolino, MD, an ophthalmologist at Massachusetts Eye and Ear, an Assistant Professor of Ophthalmology at Harvard Medical School, and first author of the paper describing the work. "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."
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%.
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. The study authors designed the contact lens to allow for a more controlled drug release. The researchers had previously shown in a 2014 study that the lens is capable of delivering medication continuously for one month.
The novel contact lens contains a thin film of drug-encapsulated polymers in the periphery. The drug-polymer film slows the drug coming out of the lens. Because the drug film is on the periphery, the center of the lens is clear, allowing for normal visual acuity, breathability, and hydration. The lenses can be made with no refractive power or with the ability to correct the refractive error in nearsighted or farsighted eyes. "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," says senior author Daniel S. Kohane, MD, Ph.D., director of the Laboratory for Biomaterials and Drug Delivery at Boston Children's Hospital.
In a study supported by a grant from the Boston Children's Hospital Technology and Innovation Development Office, 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. Further study is needed to confirm the finding in the higher-dose lenses.
The researchers are currently designing clinical trials to determine safety and efficacy of the lenses in humans.
Full details of the work appear in the journal Ophthalmology; for more information, please visit http://dx.doi.org/10.1016/j.ophtha.2016.06.038.