Dark Adaptometry As a Functional Outcome Measure in Age-Related Macular Degeneration

Abstract

 

Purpose

 

Patients with early and intermediate stages of age-related macular degeneration typically do not demonstrate visual acuity loss. However, other aspects of visual function are affected early in the disease as AMD patients often self-report night vision impairment arising from defects in rod-mediated dark adaptation and scotopic visual sensitivity. The purpose of this study is to investigate whether performance on dark adaptometry (DA) testing, as measured using the AdaptRxTM device (Apeliotus Technologies, Atlanta, GA), correlates with AMD severity.

 

Methods

 

107 patients over 50 years of age (mean age 73.9±9.5 years) were recruited from a single center for this cross-sectional, observational study. Participants were categorized based on severity of AMD into one of four categories: Group 0 with no large drusen in either eye (n = 45), Group 1 with large drusen in only one eye (n = 9), Group 2 with large drusen in both eyes (n = 32), and Group 3 with large drusen in one eye and advanced AMD in the other eye (n = 21). Dark adaptometry using the AdaptRxTM (Apeliotus Technologies, Atlanta, GA) was performed in one study eye (eye with large drusen in Group 1 and eye without advanced AMD in Group 3) in each participant at baseline and week 1. Mean rod intercept times were compared between groups using Kruskal-Wallis and Wilcoxon rank-sum testing. Test repeatability was determined using limits of 95% agreement between baseline and week 1 values.

 

Results

 

The mean rod intercepts demonstrated a correlation with increased severity of AMD with groups 2 and 3 rod intercept times reaching statistical significance when compared to group 0 (p<0.01) (see Figure). Seventeen patients out of the total exceeded the 40 minute test time ceiling and were conservatively assigned a 40 minute rod intercept time. Limits of agreement analysis between baseline and week 1 rod-intercept times on the subset of 76 patients with both time points showed a mean difference of 0.34 +/- 3.09.

 

Conclusions

 

Dark adaptometry may reveal defects in rod-mediated dark adaptation in eyes with non-advanced AMD and increase with severity of AMD. Further prospective investigation is underway to determine the relationship of AMD progression to rod intercept time.

 

 

Keywords: 412 age-related macular degeneration