We investigate whether ocular and person-based characteristics are associated with dark adaptation (DA) measured using the AdaptRx™ device (Apeliotus Technologies, Atlanta, GA).
116 participants >50 years with a range in age-related macular degeneration (AMD) severity.
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.
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/m 2 (a decrease of 3 log units), or until a maximum test duration of 40 minutes was reached.
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.
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 (R 2=0.56) with the presence of RPD conferring the largest parameter estimate.