The effects of simulated cataract on reading with normal vision and simulated central scotoma

Abstract

Reading rates are slower for persons with low vision than for normally-sighted persons. This study investigated the change in reading performance and reading eye movements when we simulated the two most common causes of low vision--central field loss and cataract--and their combination (scotoma + cataract). Three subjects read sentences with each of these simulated impairments at five different letter sizes. They required larger letters to read with the cataract or scotoma than they did with normal vision, and larger still to read with scotoma + cataract; the change in eye movements relative to normal vision was similar across conditions. When reading large letters (1.61 degrees), the cataract had almost no effect, while the scotoma and scotoma + cataract reduced reading rate for two of the subjects. The cataract had a greater impact on performance relative to normal vision for these same two subjects, while for the third subject the cataract had a greater impact with the scotoma in place. Cataract extraction tends to be postponed in patients with central field loss because it is not perceived to be beneficial. The findings from this study, as well as others, suggest that patients with central field loss would benefit from cataract extraction.

Binocular Coordination of Saccades During Reading In Strabismic Children

“…Furthermore, Kanonidou et al reported more regressive saccades and longer fixation durations, but similar saccadic amplitudes in strabismic subjects with respect to controls. 8 These findings, together with results from patients with central field loss 9 or from normal subjects with simulated central scotomas, 10 are in line with the hypothesis that a reduced or impaired visual span leads to impaired reading capabilities.…”

Slow reading in children with anisometropic amblyopia is associated with fixation instability and increased saccades

“…The relationship of reading rate and the number of saccades is consistent with previous studies of reading in strabismic amblyopia 2,3,6 and with simulated central scotomas. 20 The increase in saccades during reading in our study may be due to a suppression scotoma associated with anisometropic amblyopia. 21 Central scotomas have been shown to reduce the visual span, and they may cause inaccurate, more frequent saccades during reading.…”

Design of short Spanish sentences for measuring reading performance: Radner-Vissum test

“…If this is not possible, use 2 words with 1 syllable or 1 word with 2 or 3 syllables but no longer than 6 letters. (10) In line 3, the first and last words are 3 syllables and 7 to 8 letters. Of the other 2 words, at least 1 should have 1 or 2 syllables and should not exceed a certain number of letters.…”

“…Considering the increasing relevance of reading performance in clinical routine and research, [9][10][11] international standards should be applied to the evaluation of reading performance. Some of the principles of standardization outlined above have been used to design new reading charts.…”