Progression of Retinitis Pigmentosa on Multimodal Imaging: The PREP-1 Study

Abstract

Purpose : It is important to quantify the rate of progression of retinitis pigmentosa (RP) for various tests to determine if they can be suitable outcome measures for clinical trials. We performed a retrospective longitudinal study to measure the rate of progression using spectral-domain optical coherence tomography (SD-OCT), fundus autofluorescence (FAF) and microperimetry (MP) in a large cohort of RP patients.

Methods : Health records from RP patients at the Wilmer Eye Institute over the last 10 years were identified. Demographics, characteristics and visual acuity (VA) were recorded, and each modality was graded at baseline and every annual follow-up. SD-OCT was graded for the width of ellipsoid zone (EZ), FAF was graded for the diameter (RD) and area (RA) of the hyperautofluorescent ring (if present), and MP was graded for mean (MS), central (CS) and paracentral sensitivity (PS). Spearman’s rank correlation coefficient was used to measure correlation between parameters at baseline. Mixed effects models were used to estimate the progression of each parameter, adjusted for disease duration.

Results : A total of 205 eyes from 106 patients (mean ± SD age: 50 ± 19 years; males: 51%) were included the study, 68% of whom had been diagnosed within 10 years prior to baseline. SD-OCT was available for 205 eyes with a median (range) follow-up of 2 (1-5) years, FAF for 172 eyes with a follow-up of 2 (1-5) years, and MP for 66 eyes with a follow-up of 1 (1-4) years. A hyperautofluorescent ring was present in 67% of eyes. VA was only correlated with functional measures (MS and CS; r= 0.372 and 0.394 respectively; p= 0.01 for both). However, except for PS, all test parameters were strongly correlated with each other (r: 0.673 - 0.991; p<0.001 for all). The annual rates of change for each parameter were as follows: VA, -2.3 letters (p<0.001); EZ, -151um (p<0.001); RD, -132um (p<0.001); RA, -0.4mm² (p<0.001); MS, -0.3 dB (p<0.001); CS, -0.7 dB (p<0.001); PS, -0.4 dB (p<0.001). Only anatomic measures (EZ, RD and RA) had a rate of change that exceeded known limits of test-retest variability.

Conclusions : Structural and functional measures are well correlated in RP and combining them can provide a high degree of sensitivity and reliability in measuring disease progression within the course of a year. Therefore, SD-OCT, FAF, and MP may provide useful and reproducible outcome measures for future clinical trials to detect progression of RP.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.