Purpose: To determine the relationship between structural and functional changes over time in the progression of geographic atrophy (GA) as assessed by defect-mapping microperimetry, an approach optimized to characterize the spatial extent of deep visual sensitivity losses.
Methods: A total of 57 eyes from 50 participants underwent defect-mapping microperimetry testing of the central 8° radius (with a 10-dB stimuli presented once each at 208 locations) over a median of five visits, scheduled at 3-monthly intervals. GA lesion(s) on fundus autofluorescence in the corresponding region tested on microperimetry at each visit were manually annotated.
Results: At a global level, change of GA extent in the central 8° radius explained a large proportion of the variance in the change in the proportion of locations missed (nonresponse) on defect-mapping microperimetry (R2 = 0.52). Locally, test locations that were entirely outside or within GA lesion(s) had a 0.3% (P = 0.305) and 2.3% (P < 0.001) probability of worsening between the two visits, respectively. In contrast, test locations with a 0% to 25%, 25% to 50%, 50% to 75%, or 75% to 100% change in the extent of GA overlapping between visits had a 4.1%, 12.0%, 17.5%, and 37.9% probability of worsening, respectively (all P < 0.001).
Conclusions: This study confirms that longitudinal changes in GA extent are associated with functional changes on defect-mapping microperimetry, both on a global and local level. These findings highlight the expected functional relevance of GA progression, and demonstrates the potential effectiveness of this microperimetry testing strategy for capturing visual function decline associated with GA progression.