Objective: To examine the relation between low-contrast letter acuity, a new visual function test for multiple sclerosis (MS) trials, and vision-targeted health-related quality of life (HRQOL).
Methods: Patients in this cross-sectional study were part of an ongoing investigation of visual function in MS. Patients were tested binocularly using low-contrast letter acuity and ETDRS visual acuity (VA) charts. The 25-Item National Eye Institute Visual Functioning Questionnaire (NEI-VFQ-25), 10-Item Neuro-Ophthalmic Supplement to the NEI-VFQ-25, Impact of Visual Impairment Scale (IVIS), and Short Form-36 Health Survey (SF-36) were administered.
Results: Among 167 patients, the mean age was 48±10 years, with median Expanded Disability Status Scale 2.0 (range 1.0 to 7.5), and median binocular Snellen acuity equivalent (ETDRS charts) 20/16 (range 20/12.5 to 20/100). Reductions in vision-specific HRQOL were associated with lower (worse) scores for low-contrast letter acuity and VA (p<0.001, linear regression, accounting for age). Two-line differences in visual function were associated, on average, with >4-point (6.7- to 10.9-point) worsening in NEI-VFQ-25 composite, reductions that are considered clinically meaningful. Scores for the 10-Item Neuro-Ophthalmic Supplement to the NEI-VFQ-25 also correlated well with visual function. Associations between reduced low-contrast acuity and worse vision-targeted HRQOL remained significant in models accounting for high-contrast VA, EDSS, and history of acute optic neuritis.
Conclusions: Low-contrast letter acuity scores correlate well with HRQOL in MS. Two-line differences in scores for low-contrast acuity and VA reflect clinically meaningful differences in vision-targeted HRQOL. Low-contrast acuity testing provides information on patient-reported aspects of vision, supporting use of these measures in MS clinical trials.