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Yaping Joyce Liao, Jeehey Song, Ali Shariati, Dylan Hwang; Gaze Changes During Visual Behavior in Hemianopia. Invest. Ophthalmol. Vis. Sci. 2017;58(8):1328.
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© ARVO (1962-2015); The Authors (2016-present)
Patients with homonymous hemianopia (HH) due to stroke, tumor, and other brain lesions experience difficulties with reading and visually based activities, but exactly why this occurs is not well understood. In this study, we assessed reading and vision disability in patients with acquired hemianopia and performed eye movement recordings to analyze why reading is more difficult.
We recruited 12 patients with homonymous visual field defects and 24 age-matched controls at a single academic institution per approved protocol. We assessed vision disability using the National Eye Institute visual functioning questionnaire (VFQ-25) and 10-item neuro-ophthalmic supplement (NO-10). We measured reading speed using the King-Devick test and meausred reading speed into the blindfield (e.g. reading left to right in patient with right HH). Seven HH patients and 7 controls were recruited to participate in a study with 500-Hz infrared oculography (RED500, SensoMotoric Instruments, Germany) in order to measure fixation and saccade parameters.
Compared with age-matched controls, patients with homonymous visual field defect read 15% slower on the King-Devick rapid number naming test (HH: 59.1 ± 4.5 sec, control: 51.5 ± 2.2 sec, P = 0.12) and had worse vision disability scores. While reading into the blindfield, HH patients read 22% slower compared with controls. Infrared oculography revealed that slower reading into the blind hemifield was because HH patients spent 40% more time in fixation but made similar number of eye movements of similar saccade amplitudes and velocities relative to controls.
Patients with hemifield defect read 22% slower into the blindfield compared with controls. Such difficulty likely accounts for the greater vision disability in activities of daily living. High-speed eye movement recording revealed that slower reading in patients with hemianopia was due to 40% greater time spent in fixation but not due to changes in the saccade paramters such as saccade number, amplitudes, or velocities. Thus, reading difficulties in hemianopia is related to a change in the pattern of gaze as a result of vision loss rather than in the eye movements.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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