Abstract
Purpose: :
One of the most common complaints of glaucoma patients is difficulty reading. However, only individiuals with severe bilateral glaucoma have slower reading speeds when tested using standardized short passages of text. Here, we test the hypothesis that difficulty reading in glaucoma primarily manifests when reading over prolonged durations.
Methods: :
Glaucoma patients with bilateral visual field loss and control subjects without significant visual field loss (as defined by standard automated perimetry) completed two tests of reading. Out-loud reading was evaluated using a short International Reading Speed Text (IREST) passage, while prolonged silent reading was evaluated over 30 minutes using a standardized passage with reading speed calculated from the timing of page turns.
Results: :
Seventy-four subjects completed the study procedures, including 38 subjects with glaucoma and 36 control subjects. Glaucoma subjects did not differ from control subjects with regards to age, race, gender or level of education (p > 0.1 for all). Out loud reading was slower in glaucoma subjects as compared to controls (150 vs. 164 wpm, p=0.02), as was silent reading speed over the full 30 minute reading interval (191 vs. 217 wpm, p=0.1). In multivariable models adjusting for age, race, and education, out loud reading was 1.6 wpm slower for each 1 dB worsening in the better-eye visual field mean deviation (p < 0.001, 95% CI = 0.9 - 2.4), while reading speed over the 30 minute silent reading period was 3.8 wpm slower per dB of better-eye visual field worsening (p=0.001, 95% CI = 1.6 - 5.9). During the 30 minute silent reading period, reading speed increased by 28 wpm/hour in the median control subject, and decreased by 33 wpm/hour in the median glaucoma subject (p=0.07). In multivariable logistic regression models, reading speed was more likely to slow down by at least 30 wpm/hour of reading among glaucoma subjects as compared to control subjects (OR = 3.5, p=0.02, 95% CI = 1.2 to 10.3).
Conclusions: :
Glaucoma patients fatigue when reading over long durations, as evidenced by the high frequency with which reading speed slows down over prolonged reading, and the greater impact of visual field loss on prolonged reading speed as compared to reading speed over short durations. Discussions with patients regarding difficulty reading and interventions to improve reading ability in glaucoma should focus on prolonged reading tasks.
Keywords: reading • quality of life • visual fields