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Slow Reading in Glaucoma: Is it due to the Shrinking Visual Span in Central Vision?
MiYoung Kwon1, Rong Liu1, Bhavika N Patel1
1Department of Ophthalmology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States.
Investigative Ophthalmology & Visual Science
|November 14, 2017
Summary
Glaucoma patients read slower due to a reduced visual span, the number of letters recognized at once. This shrinkage in visual span is the primary factor affecting reading speed in individuals with glaucoma.
Area of Science:
- Ophthalmology
- Neuroscience
- Human Physiology
Background:
- Glaucoma is a leading global cause of irreversible blindness.
- It is characterized by progressive damage to retinal ganglion cells.
- Patients with glaucoma often experience difficulties with tasks like reading.
Purpose of the Study:
- To investigate the factors contributing to slower reading speeds in glaucoma patients.
- To identify the most significant predictor of reading speed in individuals with glaucoma.
Main Methods:
- The study included 17 primary open-angle glaucoma patients and 21 healthy controls.
- Measurements included binocular visual acuity, contrast sensitivity, stereoacuity, visual field mean deviation, and visual span.
- Oral reading speed was assessed using short text blocks.
Main Results:
- Glaucoma patients exhibited significantly slower reading speeds (19% slower) and smaller visual spans (11 bits smaller) than controls, even after accounting for age.
- While visual acuity was largely preserved, patients showed deficits in contrast sensitivity, stereoacuity, and visual field.
- Multiple regression analysis identified visual span as the best predictor of reading speed in glaucoma.
Conclusions:
- Slower reading speed in glaucoma is strongly associated with a reduced visual span.
- These findings reinforce the critical role of visual span in limiting reading speed for glaucoma patients.
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