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Angela Oh, Tiffany Chen, Ali Shariati, Naz Jehangir, Rosa Yu, Caroline Yu, Carmel Mercado, Yaping Joyce Liao; Ocular motor abnormalities during saccadic reading in different neuro-ophthalmic diseases. Invest. Ophthalmol. Vis. Sci. 2018;59(9):2175.
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Neuro-ophthalmic conditions like stroke, cancer, trauma, and neurodegeneration often lead to vision field loss, eye movement abnormality, or both, resulting in difficulties with common daily visual functions such as saccadic reading. In this study, we investigate reading difficulties in four different groups of neuro-ophthalmic patients using a simple rapid number reading test and infrared oculography for eye movement recording.
We performed a case control study to assess reading and visual disability at a single institution in controls and patients with different neuro-ophthalmic diseases. Subjects read 120 regularly-spaced single digit numbers to assess basic ocular motor abilities necessary for left-to-right saccadic reading without semantic context. Some underwent 500-Hz binocular 2D infrared oculography (SMI) in order to quantify their saccade and fixation parameters during number reading.
5 groups of over 200 subjects (126 controls, 18 hemianopia, 12 down-beating nystagmus, 57 Parkinson’s disease, 10 cerebellar ataxia) completed regularly-spaced single digit number reading on a book while their reading time was recorded. Patients with cerebellar ataxia read the slowest, 56% slower than controls (p = 0.001), followed by down-beating nystagmus (35%, p < 0.0001), hemianopia (27%, p = 0.005), and Parkinson’s disease (25%, p < 0.0001). Additional infrared oculography of 70 subjects revealed different patterns of impaired saccadic reading. Patients with hemianopia exhibited striking spatial bias toward their visual field defect. In contrast, patients with eye movement abnormality due to down-beating nystagmus and cerebellar ataxia did not exhibit any spatial bias but made significantly greater number of saccades and fixations (DBN, p = 0.002; ataxia, p < 0.05), with smaller saccade amplitudes (p ≤ 0.01), slower saccade velocities (p < 0.05), and greater fixation dispersion (p < 0.05). Patients with Parkinson’s disease also exhibited no spatial bias and had significantly increased number of saccades and fixations (p < 0.05). However, they had normal saccade amplitudes, velocities, and fixation dispersion.
Single digit number reading test is an easy way to assess reading difficulties in the clinical setting, and eye movement recording reveals a variety of ways that saccadic reading can be slowed in different neurological conditions.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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