People in most need of sight-preserving eyedrops may be the least successful in landing the therapy in their eyes, suggests a new study.

Buildup of internal eye pressure is one of the main causes of the vision damage associated with glaucoma, a potentially blinding disease that affects more than 4 million Americans, according to the Glaucoma Research Foundation. Standard treatment relies on self-administering pressure-lowering eyedrops.

But based on observations of a large number of people with glaucoma, researchers found that more than half struggled to apply these eyedrops properly - including many patients who thought their technique was perfect.

“Getting eyedrops into the eye is not the same as asking a patient to swallow a pill, or use a skin cream,” lead researcher Dr. Amy Hennessy of The Johns Hopkins Bloomberg School of Public Health, in Baltimore, told Reuters Health in an email. “It’s easier said than done.”

After noticing that many of their glaucoma patients were doing a “miserable job” of putting drops in their eyes, frequently launching them onto cheeks and eyelids, Hennessy and her colleagues decided to videotape about 200 glaucoma patients with impaired vision as they gave themselves eyedrops the way they would at home.

Most patients had been using eyedrops for at least 6 months, but when the researchers watched the videos, more than a quarter were unable to get a drop into their eye, they report in the journal Ophthalmology.

And of those that could, only about 40 percent managed to administer just one drop - the prescribed amount - onto the eye without touching the bottle to its surface. The average number of drops instilled was almost one and a half.

The study was partly funded by Alcon, an eyedrop manufacturer. One of the authors is an Alcon employee, and another has consulted for the company.

Applying either too few or too many drops could lead to insufficient treatment and faster progression of glaucoma, explained Hennessy. For example, patients could run out of the medicine before insurance allows them to refill their monthly prescription.

“What was more surprising was that patients also had a poor perception of their abilities to administer drops,” she added. A quarter of the patients who denied ever touching the bottle to the surface of their eye were observed doing just that, putting them at risk of infection.

A few of the video recordings did pleasantly surprise the team, and provided hope that the challenge was not insurmountable. “Some patients who could no longer see the eye chart had developed a system of localizing the drop over their eye,” said Hennessy, “and got it in correctly - every time!”

The researchers also looked to see what kind of factors, including sex and years with glaucoma, might influence successful application of the eyedrops. In the end, only age appeared important: Patients at least 70 years old were 60 percent less likely to apply the drops successfully compared to younger patients.

Hennessy suggests that these findings highlight the need for eye care providers to teach patients the best way to administer the drops, which is usually with a mirror, tilting the head back and placing the drop in the eye while holding down the lower eyelid. Family members and certain devices may also be of help.

“Glaucoma patients are not the only ones using drops - other areas of eye care also rely on drops,” she said. “So this is not a small problem, especially with our aging population.”

SOURCE:  Ophthalmology, online June 25, 2010.