Subretinal Drusenoid Deposits and the Loss of Rod Function in Intermediate Age-Related Macular Degeneration

Abstract

Purpose: To compare static rod function obtained with and without photobleach in control and intermediate age-related macular degeneration (iAMD) participants with and without subretinal drusenoid deposits (SDD). Methods: In this cross-sectional study, retinal sensitivities within the central 24° retina were obtained twice using a dark-adapted chromatic perimeter, both with 505- and 625-nm stimuli. Tests were performed after 30 minutes of dark-adaptation either with or without a preceding photobleach. Multimodal imaging was performed to grade AMD and SDD status, and other retinal changes considered being risk factors for progression to late AMD. The sensitivity difference between both stimuli was used to assess rod function. The average point wise sensitivity difference (PWSD) was compared among the study groups. Results: Twenty-nine control subjects and 20 iAMD without SDD and 17 iAMD with SDD cases were recruited. The average PWSD of the SDD group was significantly reduced (more with photobleach) compared with that of the control (P < 0.001) and no-SDD groups (P < 0.001), but only within the central 8°. The average PWSD of the non-SDD group was also reduced compared with the control group but only for measurements with photobleach (P = 0.020). There was no difference in average PWSD between the presence and absence of hyperreflective foci and/or nascent geographic atrophy in iAMD eyes without SDD (P = 0.60) or with SDD (P = 0.12). Conclusions: iAMD eyes with SDD are associated with worse static rod function compared with eyes without SDD. The greatest abnormality in rods is observed within the central 8° and when tested with a preceding photobleach.