Dilation can affect glare measurements in cataract patients

CHICAGO — Dilating pupils can cause overestimation of glare measurements in cataract patients, according to a speaker here.

"Glare is one of the most common problems patients with cataract report to their eye physician," Inci I. Dersu, MD, said at the American Society of Cataract and Refractive Surgery annual meeting.

Dr. Dersu and colleagues reported on 45 cataract patients. They measured one eye of each patient for visual acuity and glare before and after pupil dilation. Glare was measured with a Brightness Acuity Tester (BAT, Marco).

All patients were older than 40 years and had a pre-dilation visual acuity between 20/25 and 20/50. Most patients had a grade 3 cortical cataract, Dr. Dersu said.

The average change in pupil size after dilation was 2.8 mm.

After dilation, visual acuity averaged 72 ETDRS letters, compared with 74 letters before dilation. BAT measurements decreased from a mean of 72 letters to 67 letters after dilation, Dr. Dersu said.

Overall, dilation caused a change in BAT measurement in 53.7% of patients.

However, the change in visual acuity correlated directly with the change in BAT measurement, Dr. Dersu noted.

"The measure of BAT after dilation can be predicted based on the decline in patients' vision after dilation," she said.