Distinguishing between Better and Worse Visual Acuity by Studying the Correlation with Quality of Life in Neovascular Age-Related Macular Degeneration

Abstract

To determine whether there is a level of visual acuity (VA) in neovascular age-related macular degeneration (nAMD) above which the correlation of VA with disease-related quality of life (QoL) is significantly greater than below this level. An observational, cross-sectional study. A total of 184 patients with nAMD aged at least 50 years were included in the study. In face-to-face interviews, we assessed QoL with the Macular Disease-Dependent Quality of Life (MacDQoL) questionnaire. We measured VA with standardized Radner reading charts. We used regression splines analysis with a single hinge point, with the MacDQoL score as the dependent variable and VA as the independent variable. The x-coordinate (VA) of the hinge point was varied and tested with each iteration. A second method of regression splines analysis was also performed, without a preset hinge point. The primary outcome measure is the cutoff point at or below which VA is associated with significantly less change in QoL than above this cutoff. The linear coefficients below and above the cutoff are defined as change in MacDQoL score per logarithm of the minimum angle of resolution (logMAR) unit of change in VA. With Snellen equivalent VA 0.05 (1.3 logMAR) or worse, the linear coefficient was 0.15. With VA better than 0.05, the linear coefficient was 2.40 (P value of the difference: 0.009). When VA is above 0.05, there is a stronger and significant relation between VA and QoL. At or below this level, the relation between VA and QoL approaches zero. With better VA, a difference in VA implies a significant difference in QoL. With poorer VA, a difference in VA is unlikely to imply a difference in QoL. Therefore, in treating nAMD, the aim should be to keep Snellen VA above 0.05 to have an impact on QoL. If it is certain that the best-corrected VA below 0.05 is permanent, these findings imply there may be less, if any, benefit to continue further treatment. This is to be evaluated on a case-by-case basis.