Changing Contrast Can Help Glaucoma Patients With Reading Speed

Patients with glaucoma had significantly slower reading speeds than those without glaucoma, a report in Ophthalmology Glaucoma shows. However, that reading speed was improved by increasing contrast, according to the study. The researchers also investigated changing the line spacing and font size.

The cross-sectional study looked at 35 patients with but not by increasing line spacing or font size and 32 control patients without glaucoma (mean age 63.0±12.6 years) who had a comprehensive ophthalmological examination and reading speed assessment using the Minnesota Low Vision Reading (MNREAD) test under a range of contrasts (10%, 20%, 30%, 40% and 50%), line spacings (1.0, 1.5, 2.0, 2.5, 3.0 lines), and font sizes (0.8, 0.9, 1.0, 1.1, 1.2 LogMAR). Patients had 15 tests in total. Researches used regression analyses to study the effect of varying test conditions on reading speed (or words per minute (wpm)). 

The glaucoma patients in the study had a visual field mean deviation in the better eye of -6.29±6.35 dB.

Researchers found that reading speeds were significantly slower in patients with glaucoma vs controls for 14 of the 15 MNREAD tests. These results occurred even with no significant differences in age, gender, or education between groups. 

“Increased contrast (from 10 to 50 units) was associated with faster reading speed in glaucoma patients (10.6 wpm increase per 10 unit increase in contrast (95% CI 7.4 to 13.8, P <0.001, R2=0.211). There was no significant improvement in reading speed with increase in font size or line spacing,” according to the investigation.

The study was limited in that contrast sensitivity was not separately investigated and it had a small sample size.

A potential limitation was that the researchers decided to bifurcate education level by high school education completion. “Though a similar bifurcation was used in previous studies examining the impact of glaucoma on quality of life, it is possible that there was some residual confounding based on education level. For example, patients with a university degree may have had faster reading speeds,” they report. 

Another possible limitation was how the order of reading speed tests was the same for everyone in the study, with the most demanding tests first, (ie, low to high contrast, small to large font size, etc).

“This element of study design may have introduced bias due to learning effect or fatigue, and so it would be interesting in future studies to randomize the order to reduce the risk of potential bias,” according to researchers.

Reference

Ikeda MC, Hamada KU, Bando AH, et al. Interventions to improve reading performance in glaucoma. Ophthalmol Glaucoma. April 2, 2021. doi:10.1016/j.ogla.2021.03.013.