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ABSTRACT
High- and low-contrast visual acuity (HCVA, LCVA) are potential quantitative markers of neurological dysfunction in amyotrophic lateral sclerosis (ALS). The complex nature and duration of gold standard (GS) protocols precludes widespread use in neurology settings. This study compares simplified to GS visual acuity (VA) protocols. Monocular HCVA and LCVA were measured in ALS (n = 10) and control (n = 4) subjects using six protocols, varying by two chart and three refraction methods. Intraclass correlation coefficients between simplified and GS protocols ranged from 0.83 to 0.98 (HCVA, excellent agreement) and 0.56 to 0.75 (LCVA, moderate agreement). Differences between LCVA and GS protocols exceeded test-retest reliability. Simplified HCVA protocols using LCD (liquid crystal display) tablet charts and/or pinhole correction produced valid measurements. None of the modified LCVA testing protocols produced valid measurements.
Declaration of interest
The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the article.
Funding
This work was supported by National Institutes of Health grants K12 EY 02147 and K23 EY 024345 and Research to Prevent Blindness Unrestricted awards to University of Illinois at Chicago Department of Ophthalmology and Visual Sciences and Stanford Department of Ophthalmology. King-Devick testing software was provided free of charge by the manufacturer. No funding agency was involved in the conceptualisation, design, implementation, or analysis of this study.