Visual Acuity Provides a More Meaningful Measure of Vision-Related Functioning Than Mesopic Microperimetry in...

Mesopic microperimetry is a promising tool to evaluate retinal function in clinical trials. Although visual function (VF), the ability to perform vision-related tasks, relates strongly to visual acuity (VA) in patients with age-related macular degeneration, the relationship between mesopic microperimetry and VF remains unclear.

A cross-sectional study in patients with age-related macular degeneration was performed. VF was measured by questionnaire using a subset of the National Eye Institute 25-Item Visual Function Questionnaire. The macular integrity assessment microperimeter, was used with a 4-2 staircase strategy with a 10° diameter circular grid containing 37 loci. Three interpretations of the retinal sensitivity data were calculated: the mean of the 37 thresholds (mean sensitivity [MS]), the percent-reduced threshold (PRT), and the log-transformed candela mean (MS cd log). MS, PRT, and MS cd log were tested via stepwise hierarchical linear regression and R2.

We analyzed data from 102 patients (64 females [61%]; mean age, 71.8 ± 11.2 years). VF was explained best by VA (MS; R2 VA = 0.38, MS cd log; R2 VA = 0.38, PRT; R2 VA = 0.39). All retinal sensitivities contributed significantly to total R2. In the MS cd log model (total adjusted R2 = 0.52) the combined contribution of variance explained by VA and MS cd log was 46% (partial adjusted R2 = 0.46).

Mesopic microperimetry is associated with VF but VA provides a more meaningful estimation of this same construct. These results suggest that VA provides stronger evidence of clinical efficacy.

This study relates functional tests to daily vision-related functioning.