Abstract
Purpose :
In geographic atrophy (GA) secondary to age-related macular degeneration (AMD), the optimal approaches to evaluating macular sensitivity over time are unclear. The purpose of this study was to characterize longitudinal changes in macular sensitivity using microperimetry during the 9-month natural history period of a prospective study of GA.
Methods :
Patients with GA secondary to AMD in ≥ 1 eye were enrolled prospectively at the National Institutes of Health, Bethesda, MD (NCT02564978). Participants underwent mesopic microperimetry at baseline, 3 months, and 9 months using a Nidek MP-1 microperimeter. The T-shaped test grid extended 15° temporally, 12° superiorly, and 12° inferiorly (intersection centered on the fovea), comprising 40 testing loci evenly spaced 1° apart. At each testing loci, sensitivity was measured using a Goldmann III stimulus and a 4-2 staircase strategy. The following parameters were assessed at each time point: (i) number of scotomatous loci (S), mean sensitivity in decibels (dB) (ii) of all loci, (iii) of all non-scotomatous loci (NS), and (iv) of only para-scotomatous loci averaged separately within the temporal (TPS), superior (SPS), and inferior (IPS) axes. Rate of change was analyzed by linear regression.
Results :
The study population comprised 30 eyes of 30 patients (mean age 74.1 years). Mean follow-up for microperimetry was 8.2 months. Table 1 summarizes baseline data and rate of change for all parameters. Mean sensitivity ± SE (dB/month) decreased significantly for TPS loci (-0.33 ± 0.11; p=0.002), SPS loci (-0.28 ± 0.09; p=0.004) and IPS loci (-0.40 ± 0.10; p=0.001) during the follow-up period. There were no significant changes in the mean sensitivities of all loci (-0.09 ± 0.10; p=0.37) or NS loci (-0.12 ± 0.10; p=0.21) over time. Additionally, there was no significant change in the number of S loci (-0.02 ± 0.23 loci/month; p=0.94) over time.
Conclusions :
Meaningful changes in macular sensitivity following GA progression can be detected by concentrating testing within para-scotomatous loci, corresponding to GA transitional zones. In contrast, time-dependent functional changes may not be evident when assessing many loci across scotomatous and non-scotomatous areas. Therefore, para-scotomatous sensitivity may serve as a useful functional endpoint for measuring GA progression.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.