Impairments in Dark Adaptation Are Associated with Age-Related Macular Degeneration Severity and Reticular Pseudodrusen

Abstract

Purpose We investigate whether ocular and person-based characteristics are associated with dark adaptation (DA) measured using the AdaptRx™ device (Apeliotus Technologies, Atlanta, GA). Design Cross-sectional, single-center, observational study. Participants 116 participants >50 years with a range in age-related macular degeneration (AMD) severity. Methods Participants underwent best-corrected visual acuity (BCVA) testing, ophthalmoscopic examination and multimodal imaging. Presence of reticular pseudodrusen (RPD) was assessed by masked grading of fundus images and confirmed with OCT. Eyes were also graded for AMD features (drusen, pigmentary changes, late AMD) to generate a person-based AMD severity groups. One eye was designated the study eye for DA testing using the AdaptRx™ device. Nonparametric statistical testing was performed on all comparisons. Main Outcome Measure The primary outcome of this study was the rod-intercept time (RIT) which is defined as the time for a participant's visual sensitivity to recover to a stimulus intensity of 5 × 10−3 cd/m2 (a decrease of 3 log units), or until a maximum test duration of 40 minutes was reached. Results A total of 116 study eyes in 116 participants (mean age=75.4±9.4 years, 58% female) were analyzed. Increased RIT was significantly associated with increasing age (r=0.34, p=0.0002), decreasing BCVA (r=−0.54, p<0.0001), pseudophakia (p=0.03), decreasing subfoveal choroidal thickness (r=−0.27, p=0.003). Study eyes with RPD (15/116, 13%) had a significantly greater mean RIT compared to eyes without RPD in any AMD severity group (p<0.02 for all comparisons) with 80% reaching the DA test ceiling. Conclusion Impairments in DA increase with age, worse visual acuity, presence of RPD, AMD severity and decreased subfoveal choroidal thickness. Analysis of covariance found the multivariable model that best fit our data included age, AMD group, and presence of RPD (R2=0.56) with the presence of RPD conferring the largest parameter estimate.

Longitudinal Changes in Retinotopic Rod Function in Intermediate Age-Related Macular Degeneration

“…3,13,14 While we found a significant delay in RIT at follow-up, the exact magnitude of the increased RIT in eyes with RPD could not be estimated in our study because many of the test points were already severely abnormal and failed to reach the rod criterion level within the 20 minutes after an approximate 30% bleach. Nevertheless, iAMD eyes with RPD consistently had a greater proportion of test points with longer RIT or test points that failed to reach the criterion level compared to iAMD without RPD.…”

“…1 The cause of this symptom appears to be associated with the impairment or loss of rod photoreceptors, as studies assessing rod function using dark adaptation show that rod-mediated dark adaptation (DA) parameters are markedly abnormal in eyes with early stages of AMD. [2][3][4][5] In addition, histologic studies demonstrated a decline in rod density in AMD eyes. 6,7 Studies have also shown that the magnitude of rod dysfunction increases with increasing AMD severity.…”

“…6,7 Studies have also shown that the magnitude of rod dysfunction increases with increasing AMD severity. [2][3][4]8 Hence, rod function may have a potential role in monitoring AMD progression.…”

“…Moreover, recent studies have shown that iAMD eyes with reticular pseudodrusen (RPD) exhibit greater DA impairment and are at increased risk of progression to late AMD than iAMD eyes without RPD. 3,9 Hence, there is also a particular interest in exploring longitudinal and retinotopic changes in iAMD eyes with RPD. We have recently reported in a cross-sectional study the retinotopic variation in rod function in subjects with iAMD, with the use of a dark-adapted chromatic perimeter (DACP; Medmont, Melbourne, Australia).…”

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

“…Although this study examined static rod function, our findings are in agreement with those reported in previous studies where rod recovery was assessed. 19,26,27 In addition, we have further shown that static rod function of iAMD cases without SDD was indistinguishable from control cases when tested without photobleach. A difference in static rod function between iAMD without SDD and control group was only observed when tested with preceding photobleach.…”