A study by the Johns Hopkins University's Wilmer Eye Institute found people with glaucoma in both eyes (bilateral) read 29 words per minute slower than those without glaucoma. They also were almost twice as likely to have reading impairment.

Those with glaucoma in one eye (unilateral) had rates about on par with those without the condition, which can cause eye damage and vision loss.

The findings were published in the January issue of Archives of Ophthalmology.

The authors noted that education levels and race may also have played into the lower scores.

"As reading out loud was necessary to measure reading speed, racial differences in speaking rates could account for the difference in the measured reading rate," the authors wrote. "Future work should evaluate reading in subjects with glaucoma under more realistic conditions to further explore if reading impairment is more prevalent than reported herein."

More information

The U.S. National Library of Medicine has more about glaucoma.