Abstract
Purpose :
Progression rates of PRPH2-associated retinal dystrophy have not been described. We used structural and functional outcome measures to establish disease progression rates in best-corrected visual acuity (BCVA), total lesion size (TLS), dark autofluorescence (DAF) area, total macular volume (TMV) and mean macular sensitivity (MMS).
Methods :
In this retrospective case series, patients with confirmed heterozygous pathogenic PRPH2 variants, 6 monthly serial BCVA, ultra-widefield (UWF) fundus autofluorescence (FAF), optical coherence tomography and MAIA microperimetry with at least 1 year of follow up were included. Linear regression was performed for each eye of each subject to determine the rate of change. Changes in TMV and MMS were compared to a cohort of normal controls.
Results :
A total of 12 patients (mean baseline age=55, F:M=4:8) from 10 unrelated families were followed for a mean (SD, range) of 4.7 (2.1, 1.0-8.5) years. The overall mean (SD) BCVA decline was 0.91 (1.86, OD) and 2.93 (5.34, OS) letters/year with no significant interocular difference (p=0.28). Mean (SD) effective radius expansion rates in TLS and DAF were 0.16 (0.13) and 0.10 (0.08) mm/year and 0.15 (0.14) and 0.11 (0.05) mm/year in OD and OS respectively. Mean (SD) TMV decline was 0.079 (0.053, OD) and 0.071 (0.047, OS) mm3/year with no significant interocular difference (p=0.25). Healthy controls (N=42, mean age=51) showed a mean decline of 0.006 mm3/year. Overall MMS change was +0.38 (OD) and -0.72 (OS) dB/year. Four patients showed a bilateral MSS decline of 1.90 (OD) and 1.31 (OS) dB/year. Five patients showed a bilateral MSS increase of 0.61 (OD) and 0.49 (OS) dB/year attributed to learning effects. Healthy controls (N=41, mean age=51) showed a mean (SD) MSS decline of 0.02 dB/year.
Conclusions :
Patients with PRPH2-associated retinal dystrophy showed slow expansion rates in UWF-FAF derived TLS and DAF area. OCT-derived TMV may serve as an important quantitative outcome measure for future therapeutic clinical trials. Functional outcome measures however warrant further investigation given their large variability and significant learning effects.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.