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Elana Rosenberg, Stephen Moster, Reiko Sakai, James Wilson, Gary Cutter, Steven Galetta, Laura Balcer; The King-Devick (K-D) test of rapid eye movements: a bedside correlate of disability and quality of life in multiple sclerosis. Invest. Ophthalmol. Vis. Sci. 2013;54(15):2345.
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© ARVO (1962-2015); The Authors (2016-present)
The King-Devick (K-D) test, a rapid number naming test, captures impaired eye movements and saccades, findings correlated with suboptimal brain function. This test has been used to screen athletes for concussions, with worse time scores in athletes following concussion, consistent with widely distributed visual pathways. We examined the K-D test as a measure of vision and eye movements in multiple sclerosis (MS) and determined the relation of K-D scores to visual function, vision-specific quality of life (QoL), work disability, and history of optic neuritis (ON).
Patients with MS and disease-free controls completed the test at a single visit. Scores represent time needed to read single-digit numbers on 3 test cards. Patients had testing of monocular and binocular low-contrast acuity (2.5%, 1.25%), high-contrast acuity (VA), spectral-domain OCT, NEI-VFQ-25, 10-Item Neuro-Ophthalmic Supplement, and MS Functional Composite.
In the MS cohort (n=81), K-D scores were worse compared to controls (54.7±15.7 vs. 41.2±7.2 seconds, p=0.003, least squares means, adjusting for age). Higher scores in MS were associated with worse scores for vision-specific QoL (p<0.001 for NEI-VFQ-25, p<0.001 for 10-Item Supplement), binocular low-contrast acuity at 2.5%, 1.25% (p<0.001), binocular VA (p=0.003), timed 25-foot walk (p<0.001), 9-hole peg test (p=0.001), and 3-second PASAT3 (p=0.03, linear regression). Patients with history of acute ON (p=0.003) or binocular low-contrast acuities below the control group average (p=0.009 for 2.5%, logistic regression) had worse K-D scores. Correspondingly, monocular vision (p=0.001-0.009) and RNFL thickness (p=0.001) were reduced in eyes of patients with worse K-D (adjusting for age and within-patient, inter-eye correlations). Disabled patients (receiving disability pension) did worse on the K-D test compared to those working full-time, accounting for age (p<0.001).
The K-D test captures visual dysfunction, vision-specific quality of life and neurologic impairment in MS. Scores reflect work disability as well as structural changes as measured by OCT. History of ON and abnormal binocular acuities were associated with worse scores, suggesting that the K-D captures both afferent and efferent components of vision. The K-D test should be considered for future MS trials as a rapid global visual performance measure.
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