© 2022 MJH Life Sciences and Optometry Times. All rights reserved.

© 2022 MJH Life Sciences™ and Optometry Times. All rights reserved.

Clinical trials evaluate corneal staining changes in patients.

“Editor’s note: The following article includes results based on a manuscript, published in Clinical and Experimental Optometry, viewable here. During the last decade, research and development of ophthalmic drugs have produced exciting new mechanisms of delivery—such as sustained-delivery implants and mucus-penetrating nanoparticles—that improve drug performance, minimize side effects, and reduce concerns about patient compliance with eye drop regimens.

Contact lenses have been singled out as a promising mechanism, with investigations of drug-eluting lenses for infection, dry eye disease (DED), glaucoma, and allergies now underway.1

The first drug-eluting contact lens was approved by the FDA earlier this year (Acuvue Theravision with Ketotifen [Johnson & Johnson Vision]), an etafilcon A daily disposable that delivers the antihistamine ketotifen commonly used in allergy eye drops.

The efficacy of the contact lens was comparable to that of eye drops.2 Because this is a new drug delivery modality, in the course of the clinical studies for this lens, my colleagues and I compiled additional data to evaluate how the lens affects corneal epithelium integrity over the course of long-term daily wear (12 weeks).

We analyzed 2 clinical trials with identical multisite, randomized, controlled designs and more than 500 patients in total. The results, published recently in Clinical and Experimental Optometry, painted a promising picture for patients, practitioners, and the future of this modality.3

Chronic use of eye drop medications is known to cause conjunctivitis medicamentosa—eyes that are red, irritated, and burning after continued exposure to the drop’s ingredients, most notably the preservative.4

The discomfort not only affects patients’ daily activities and quality of life, but also discourages continued compliance with eye drops because patients don’t want to add more drops to already irritated eyes.5

When patients have this condition, corneal staining often reveals compromised integrity of corneal epithelial cells, signaling that treatment must be adjusted to help the eye heal and prevent further damage.

Avoiding harsh chemicals in eyes susceptible to irritation, like those compromised by allergies, is particularly important to minimize conjunctivitis medicamentosa.

Frequent dosing is often necessary because eye drops have low bioavailability—just 5%-10% of the drug is available to the ocular surface6—and are quickly washed out by blinking and tearing.

Drug-eluting contact lenses offer multiple benefits that can eliminate some of the challenges associated with eye drops, including:

Medication is incorporated into the lenses during the manufacturing process, which also includes a sterilization step in an autoclave. They therefore require no preservative, such as BAK, which degrades junctions between corneal epithelial cells. Each lens provides a sterile dose of medication.

A drug-eluting contact lens delivers medication over several hours, so it has a much higher residence time on the ocular surface compared to eye drops, which quickly wash away. The diffusion-based release profile of a contact lens allows it to provide consistent dosing, rather than the frequent dosing required with some eye drops.

When medication is combined with vision correction in a comfortable etafilcon A daily disposable contact lens, patients don’t have to think about their medication schedule. This is a particularly promising advantage for patients who have trouble adhering to their schedule.

A drug-eluting contact lens may solve some of the problems associated with eye drop medications, but for eye care professionals, the next logical question is, “What is the effect on the ocular surface of wearing a medicated lens every day?”

My colleagues and I analyzed data from 2 identical clinical safety trials that lasted 12 weeks and enrolled a total of 560 contact lens wearers. The test lens was worn by 374 patients, and a placebo lens by 186 patients.

Corneal staining with fluorescein was performed at baseline and then at 1, 4, 8, and 12 weeks of lens wear. At all visits, there was no statistical difference in staining between the drug-eluting lens group and the placebo group (95.86% and 95.88% Grade 0, respectively, at 12 weeks). All staining was mild or trace.

After 4 weeks of wear, patients in both groups exhibited less corneal staining on average compared to baseline. This noteworthy shift may be attributable to patients changing from their regular contact lenses to the new material (etafilcon A, which has a high water content7) and/or wear schedule (daily disposable, which removes lens cleaning solutions from the equation). Compliance with study lens wear was similar in both groups (about 92%).

In summary, in well-controlled, double-masked clinical trials with a large sample size, we can very confidently conclude that this antihistamine-releasing contact lens does not significantly impact corneal epithelial integrity.

Eyes wearing this drug-eluting contact lens should not look any different than eyes wearing a nonmedicated contact lens—an essential factor in the seamless integration into a practice of this modality.

Nothing about the lens fitting process or on-eye evaluation is different. Patients simply need a little more education about the lenses, and then they can get the vision they expect with additional help for ocular allergies.

Evidence that the addition of antihistamine did not increase corneal epithelial damage relative to standard contact lenses is encouraging as we look ahead to more applications of the drug-eluting modality.

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