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Editors Selection IGR 11-2

Visual Impairment: Vision loss and reading ability

Comment by David Friedman on:

60354 Severity of Vision Loss Interacts with Word-Specific Features to Impact Out-Loud Reading in Glaucoma, Mathews PM; Rubin GS; McCloskey M et al., Investigative Ophthalmology and Visual Science, 2015; 0:

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Reading is slower and more difficult for individuals with glaucoma. Matthews and colleagues, in an attempt to help develop better methods for reading rehabilitation in glaucoma patients, assessed what text factors led to greater reading difficulty. In order to determine this, the investigators had those with glaucoma and control subjects read standardized text (fifth grade level) out loud. The researchers abstracted voice recordings to identify how long it took to say each word and how long the intervals were between words. Visual acuity and contrast sensitivity (CS) were measured binocularly. Those with glaucoma were on average four years older than controls, but otherwise were similar, and those with glaucoma had an average mean deviation in the better-eye visual field of 8.9 dB. Words that were longer required more time to read and reading longer words also increased the interval before the next word. Similarly, words at the end of a line of text required longer to read and the interval to the next word was also longer.

One simple approach suggested by the authors would be to instruct glaucoma patients to read in landscape mode to reduce the number of line shifts in tekst

Those with glaucoma took longer to say words (both short and long words) and had a longer delay before saying the next word. There was a substantial increase in the delay between ending the last word of a line and starting the first word on the next line. CS was more strongly correlated with reading findings than visual field although both were associated. Using CS as a reflection of glaucoma severity, the length of time needed to read was substantially longer with worsening CS (i.e., they interacted). Those with increasing degrees of loss of CS had even greater difficulty with words that were longer, relatively uncommon, and those at the end of a line of text. Also, mispronunciation or misidentification of words was increasingly common among those with more severe glaucoma. Word length interacted the most strongly with CS and reading speed.

This work required incredible attention to detail and precise measurement and the authors are to be commended. They have made an important contribution to our understanding of the impact of glaucoma on reading and the findings will be useful for those designing systems to improve reading despite loss of CS in glaucoma. One simple approach suggested by the authors would be to instruct glaucoma patients to read in landscape mode to reduce the number of line shifts in text. Other innovations could also be incorporated into reading devices. The authors note that vision loss from glaucoma currently cannot be reversed, but disability from that loss can be reduced.

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