Drug-eluting contact lenses may be the way of the future for the delivery of certain eye medications, according to two researchers involved in developing the lenses.
In this month’s issue of Expert Review of Ophthalmology, Harvard Medical School researchers Joseph B. Ciolino, MD, and Daniel S. Kohane, MD, PhD, discussed some of the advantages and challenges of developing these lenses.
It’s estimated that 90 percent of eye medicines are delivered to the eye in the form of eye drops. But many people have difficulty properly applying eye drops to their eyes, and less than 10 percent of the medicine in eye drops is absorbed by the eye, according to research cited by Drs. Ciolino and Kohane.
Other studies have shown that poor compliance with prescribed eye drop medications is a significant problem in the management of chronic eye diseases, such as glaucoma and ocular hypertension.
Drug-eluting contacts could improve patient compliance with their glaucoma treatment, and a sustained release of medications may prove more effective than the short bursts of the same drugs when they are administered via eye drops, the researchers say.
However, challenges to creating drug-eluting contacts include:
- The drug contained in the contact lens must not compromise the optical quality of the lens.
- The drug must not reduce the biocompatibility of the lens. (In other words, the drug must not make the lens more difficult to wear or increase the risk of eye problems such as a corneal ulcer from wearing contacts.)
- Extended release of the drug cannot be toxic to the cornea.
- The drug should not affect the physical characteristics of the lens, including its thickness and oxygen permeability.
Other design challenges include determining how much of the drug the contact lens should contain and how long the release should last.
Also, drug-eluting contacts could complicate contact lens care. Ideally, the lenses should release their drug load only when they are on the eye, not during cleaning or storage. (It’s possible that developing drug-eluting daily disposable contacts may solve this potential problem.)
Finally, it will be important to determine the cost-effectiveness of drug-eluting contacts compared with conventional treatment of glaucoma and other problems with eye drop medications.
Despite these challenges, the researchers say drug-eluting contact lenses offer the possibility of better compliance with prolonged treatment of chronic eye diseases and relief of certain eye symptoms from a single application, giving eye doctors a new and more effective means to treat ocular diseases and conditions.
[Ed. note: To date, drug-eluting contact lenses are not FDA-approved for use in the United States.]