Reading ability and quality of life in stargardt disease

Purpose: To study the reading performance of patients with Stargardt disease (STGD) and the relationship between clinical vision measurements and vision-related quality of life (VRQOL). Methods: We studied both eyes of 16 patients with STGD. Each patient was examined for best-corrected visual acuity (Early Treatment Diabetic Retinopathy Study [ETDRS]), reading ability (MNREAD and REX charts), contrast sensitivity (Pelli-Robson charts), fixation study (MP1 microperimeter), and VRQOL (25-item National Eye Institute Visual Function Questionnaire [NEI VFQ-25]). The correlation pattern among these variables was examined and an exploratory factor analysis was used to investigate dimensionality of both visual function and VRQOL. Results: Mean ETDRS visual acuity was about 20/160 (0.9 logMAR). All studied psychophysical measures were highly or moderately correlated with MNREAD reading speed (p<0.05 level). A similar correlation was found between psychophysical measures and VRQOL, which was higher for MNREAD measures of acuity (r = -0.75) and speed (r = 0.74). Accordingly, exploratory factor analysis suggested that a single latent dimension explained most of the variance of vision psychophysical measures as well as of VRQOL. Conclusions: We propose that reading ability should be assessed in patients with STGD, since we found that both MNREAD reading speed and visual acuity are strong determinants of quality of life. The observed relation between reading ability and VRQOL in STGD suggests that in these patients appropriate low vision rehabilitation can improve both reading performance and consequently VRQOL. Finally, our data support the use of reading speed and visual acuity as important outcome measures for monitoring STGD progression.