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Robyn Burton, David P. Crabb, Nick D. Smith, Fiona C. Glen, David F. Garway-Heath; Exploring the Effects of Glaucoma on Reading Speed. Invest. Ophthalmol. Vis. Sci. 2011;52(14):5563.
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Reading is an imperative part of daily life but past research has not fully ascertained the extent to which people with glaucoma have difficulties with reading. This study has the long-term aim of establishing the relationship between reading difficulties and level of glaucomatous impairment.
Thirty glaucomatous patients (mean age: 70 [SD:8] years) with bilateral visual field defects and 27 age-similar visually healthy control subjects (mean age: 67 [SD:8] years) from a recruitment target of 60 in both groups, had reading speeds measured using sets of fixed size, non-scrolling texts on a computer set up that incorporated an eye tracking device. All participants had visual acuity better than 6/9 and underwent standard tests of visual function including Humphrey 24-2 & 10-2 visual fields (VFs) along with other tests for non-sensory confounders, including cognitive ability (Middlesex Elderly Assessment of Mental Status Test [MEAMS]) and general reading ability. Individual average raw reading speeds were calculated from 8 trials (different passages of text) at both 100% and 20% contrast. These interim results focus on one aspect of reading performance: reduction in individual average reading speed due to the decrease in contrast to examine the hypothesis that patients are more affected than controls.
Patients had an average 24-2 VF MD of -6.5 (range: 0.7 to -17.3) dB in the better eye. The overall median reduction in reading speed due to contrast lowering of the text in the patients was 20% but this varied considerably between individuals(IQR: 8-44%). This reduction was significantly worse than that experienced by the controls (median: 11% [IQR: 6-17%]; Mann-Whitney Test P=0.013). Cases and controls were similar in average performance on MEAMS (P=0.94), a modified Burt Reading ability test (P=0.13), and a computer based lexical decision task (P=0.42) and had similar self reported day-to-day reading frequency (P=0.11).
Overall average reduction in reading speed caused by a lowering of letter contrast is significantly more apparent in patients with glaucoma when compared to visually healthy people with similar age and similar cognitive/reading ability.
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