Needle Treatment for Glaucoma Shows Promise: A Monthly Injection That Might Replace Eye Drops Used Twice Daily
As reported by Ann Lukits of the Wall Street Journal, Pittsburgh scientists led by McGowan Institute for Regenerative Medicine faculty member Steven Little, PhD, chairman of the Department of Chemical and Petroleum Engineering and associate professor and CNG faculty fellow in the Departments of Chemical and Petroleum Engineering, Bioengineering, Immunology, and Ophthalmology, are working to develop new techniques to administer medication for glaucoma patients that replace the usual regimen of twice-daily eye drops, a sometimes unreliable treatment. McGowan Institute for Regenerative Medicine faculty member Joel Schuman, MD, Eye and Ear Foundation professor and chairman of the Department of Ophthalmology, with secondary appointments as professor of bioengineering and of clinical and translational science, and professor at the Center for the Neural Basis of Cognition, a University of Pittsburgh/Carnegie Mellon University collaboration, was a member of the research team as well.
A promising approach, reported in the August issue of Experimental Eye Research, involves a monthly injection of a slow-release drug directly into the eye. The technique, tested on laboratory animals, uses significantly less medication than current treatment and potentially manages the disease better, the researchers said. One injection was comparable to taking eye drops twice a day for 28 days.
Glaucoma, in which eye pressure damages the optic nerve, affects an estimated 2.7 million Americans and puts them at risk for vision loss, according to the National Eye Institute. Treatment usually involves taking eye drops multiple times a day to maintain a healthy eye pressure, but studies have shown as many as 80% of patients forget to take the drops, the researchers said. The drops can also leach into the opposite eye, causing retinal hemorrhages and other complications.
A 28-day pilot study at the University of Pittsburgh tested the injection technique on rabbits with normal eye pressure. One group of animals was injected with a biodegradable, spherical-shaped capsule called a microsphere just below the conjunctiva, or thin membrane covering the white part of the eye. The microsphere contained less than three drops of brimonidine tartrate, a glaucoma medication. Another group was injected with blank microspheres and a third received two brimonidine drops a day in the traditional way.
On average, eye pressure dropped 21.4% in rabbits injected with the slow-release drug and 19.9% in rabbits treated with eye drops. There was no significant change in eye pressure in the animals injected with blank microspheres. The microspheres didn’t irritate other eye tissues and had degraded by day 35, the researchers said.
The Pittsburgh team is testing a topical solution that would enable patients to receive the same month-long treatment without the insertion of a drug-delivery system, said Dr. Little.
To date, the microsphere drug-delivery system hasn’t been tested on humans. Also, the effects of repeated injections aren’t known. More research is necessary before this potential technology may be available to patients.
Abstract (28-day intraocular pressure reduction with a single dose of brimonidine tartrate-loaded microspheres. Fedorchak MV, Conner IP, Medina CA, Wingard JB, Schuman JS, Little SR. Experimental Eye Research, 2014 Aug; 125:210-6.)