Reading performance highlights functional impact of glaucoma

Chicago-Reading speed is reduced in patients with glaucomatous visual field loss and normal visual acuity, and the reduction in performance is directly proportional to the extent of the visual field loss, said Aron Guimaraes, MD.

“Several studies using self-reported measures have shown that patients with glaucoma have difficulty with reading performance, and there are also clinical studies showing reading speed is reduced in glaucoma patients,” said Dr. Guimares, Department of Ophthalmology, State University of Campinas, Brazil. “However, most of the latter investigations included patients with varied visual acuities, making it unclear whether the changes in reading speed were secondary to visual acuity deficit or visual field loss.

“Therefore, we investigated reading performance in patients with glaucoma and 20/20 visual acuity,” he said.

The cross-sectional study included 35 patients with primary open-angle glaucoma and 35 age-matched healthy controls. All participants had 20/20 visual acuity in the tested eye and a minimum of 8 years of schooling. The glaucoma patients and controls were well matched in terms of eye investigated, gender, mean age, and mean education.

Monocular reading performance was assessed using a validated Portuguese version of the Minnesota low vision reading test under a fixed luminance (85 cd/m²) at a distance of 40 cm with appropriate refractive correction.

The results showed the mean maximum reading speed was significantly lower in the glaucoma group compared to the controls, 125 versus 184 words per minute.

In addition mean logMAR critical print size (font size at which the reading speed begins to decrease significantly) was significantly larger for the glaucoma group than for the controls, 0.09 versus –0.01.

In analyses examining relationships between the reading parameters and severity of the visual field defect (mean deviation) among the glaucoma patients, there was a very strong positive correlation between maximum reading speed and mean deviation (r = 0.954; p = 0.01). In addition, there was a strong negative correlation between critical print size and mean deviation.

Dr. Guimares said that the design of future studies may consider evaluating binocular reading performance and whether lighting adjustment enables improved reading performance for patients with glaucoma.