Scientists from Massachusetts have created a contact lens that will deliver controlled amounts of medicine directly into the eyes of glaucoma patients continuously for up to a month.
The researchers, from Massachusetts Eye and Ear Infirmary, Harvard Medical School Department of Ophthalmology, Boston Children's Hospital and the Massachusetts Institute of Technology, believe their contact lenses could replace eye drops as a treatment for glaucoma.
The results, published in the journal Biometrics, show that an "early burst of drug release" was followed by sustained release for 1 month. The researchers believe this drug delivery system could also be used to treat other eye conditions.
Traditionally, glaucoma is treated with eye drops, but as Dr. Joseph Ciolino, cornea specialist at Mass. Eye and Ear Infirmary and lead author of the paper, explains:
"In general, eye drops are an inefficient method of drug delivery that has notoriously poor patient adherence. This contact lens design can potentially be used as a treatment for glaucoma and as a platform for other ocular drug delivery applications."
Delivery of drugs by lenses as effective as drops
Researchers have shown that contact lenses laced with medicines are an effective way of treating glaucoma patients.
The Centers for Disease Control and Prevention (CDC) estimates that 2.2 million Americans (resource no longer available at www.cdc.gov) are affected by glaucoma and that this will rise to 7.3 million by 2050.
Damage to the optic nerve leads to progressive, irreversible vision loss and is the second leading cause of blindness. As of yet, there is no cure, but medication can prevent further vision loss in most people.
The Glaucoma Research Foundation states that there are very few symptoms and stresses the importance of regular testing, at least every 2 years.
Latanoprost is one of the most commonly prescribed drugs for treating glaucoma and is usually delivered as eye drops.
The lenses were made by encapsulating polymer films containing the drug into the periphery of a brand of commonly used contact lenses. Tests showed that when using the lenses for a month, the levels of latanoprost in the eye's aqueous humor were comparable to those achieved by daily topical eye drops.
Prof. Daniel Kohane, director of the Laboratory for Biomaterials and Drug Delivery at Boston Children's Hospital, is excited about the prospects for the lenses:
"The lens we have developed is capable of delivering large amounts of drug at substantially constant rates over weeks to months."
And the researchers found that lenses containing thicker drug-polymer films released more of the drug after the initial burst.
By concentrating the polymer films in the periphery of the lens, the center is kept clear so as not to interfere with the patient's vision. Another advantage of the lenses is that they can be made with no refractive power or with the ability to correct near- or far-sightedness.
Dr. Ciolino acknowledges that getting patients to stick to their treatment plan is difficult, as people often forget to apply their drops. He concludes:
"A non-invasive method of sustained ocular drug delivery could help patients adhere to the therapy necessary to maintain vision in diseases like glaucoma, saving millions from preventable blindness."