Functional Vision Assessment Over 4 Years in USH2A Using the Veteran Affairs Low-Vision Visual Functioning Questionnaire

PURPOSE. The purpose of this study was to evaluate the validity of the Veterans Affairs Low Vision Visual Functioning Questionnaire (VALVVFQ-48) functional vision scores (FVS) in patients with USH2A-associated retinal degeneration. In addition, to correlate the change in the VALVVFQ-48 FVS with the change in visual function (VF) measurements. METHODS. The VALVVFQ-48 was administered verbally to participants ≥18 years of age at baseline, and after 2 and 4 years. Associations among changes in FVS and changes in VF measures were assessed using the Spearman correlation coefficients. Mixed effects regression models with a random intercept were used to estimate annual rates of change of FVS and their responsiveness to change in VF measurements. RESULTS. All domain scores (except visual motor) showed significant decline over 4 years. Changes in the VALVVFQ-48 domain scores were negligibly to strongly correlated with changes in clinical measures of vision function over 4 years (|r| = 0.02 to 0.61). All domains showed evidence of responsiveness to changes in some VF measures, particularly the visual field. Participants with improvement and worsening in FVS beyond the coefficient of repeatability (CoR) ranged between 17% and 46% across all domains. Ceiling effects at baseline precluded accurate calculation of change over time in 19% to 36% of participants in 3 domains. CONCLUSIONS. The VALVVFQ-48 may not be a sensitive measure for evaluating longitudinal outcomes in all persons with USH2A-associated retinal degeneration.