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Reading performance worse in all stages of glaucoma, study finds
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Patients with glaucoma, even at the early stage, read slowly and with more errors as compared with normal subjects, according to a study.
At the University of Turin, Italy, a group of 80 patients with early-stage or moderate primary open-angle glaucoma and 60 healthy controls were tested for reading performance with the Radner Reading Charts.
Although visual acuity did not differ significantly between the two groups, glaucoma patients read more slowly and with more errors. Reading speed was reduced by a mean of 27 words per minute as compared with healthy subjects, and the critical print size was larger than the print for controls. Average reading speed linearly decreased with reduction of visual field and reading acuity.
Decreased reading ability at the early stages of glaucoma may be correlated with decreased contrast sensitivity due to the loss of retinal ganglion cells, which occurs earlier than any detectable loss of visual field, the authors noted. Disruption of the magnocellular visual pathway, which is involved in maintaining eye fixation and directing saccadic eye movements, may also require a higher amount of attention and a longer time to focus on a target and identify letters.
In addition to being essential for everyday life, reading is also a surrogate measure for other activities of daily life, such as walking, stair climbing, face recognition and driving.
“Thus, reading performances could be a good indicator of the patient's quality of life, which has recently become a primary goal of the effectiveness of glaucoma treatment,” the authors wrote.
“Futures studies should focus on factors affecting reading speed in glaucoma to develop reading rehabilitation for these patients,” they concluded. – by Michela Cimberle
Disclosure: The authors reported no relevant financial disclosures.
Perspective
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Mark Eltis, OD, FAAO
While we tend to think of primary open angle glaucoma as a generally slow-moving process, it can have important consequences early on. Functional ability can be significantly affected despite the patient not having field loss or easily detectable optic nerve damage. Even early glaucoma has a detrimental effect on the magnocellular visual pathway, which controls eye fixation and saccadic eye movements.
This study invites us to alter our perspective of glaucoma as a disease of peripheral vision loss. Reading, aside from being a critical skill, can also improve quality of life. Studies report that up to 50% of retinal ganglion cells are already dead when a visual field defect is detectable. Clearly, this should serve as motivation for employing any techniques and technology at our disposal to expedite detection and diagnosis. We must also not dismiss nonspecific complaints of patients with daily tasks that we don’t conventionally associate with preperimetric glaucoma. Reading charts such as the Radner Reading Chart may serve to detect, classify and grade visual impairment for our patients. Finally, a greater emphasis should be placed on vision rehabilitation assessment and treatment for glaucoma sufferers in practice at every stage of this insidious disease.
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