Correlations between progression markers in rod-cone dystrophy due to mutations in RHO, PDE6A, or PDE6B.

Abstract

Purpose : Using accurate and robust markers to evaluate the course of rod-cone dystrophy, also known as Retinitis Pigmentosa (RP), remains pivotal for a better understanding of the disease and for the evaluation of new treatments. Using the data collected in the PHENOROD 1 study (NCT03975543), we analyzed the correlation between structural and functional parameters.

Methods : Data was extracted from 110 medical records (between 2007 and 2019) of patients followed at the National reference center for rare diseases of Quinze-Vingts Hospital (Paris, France). The evidence of mutations in RHO, PDE6A, or PDE6B, at least 2 visits, and no other condition impacting vision than RP were the inclusion criteria for this study. Intra-ocular pressure, best-corrected visual acuity (BCVA), color vision alteration on the panel D-15, static and kinetic visual field, the preservation of the hyper reflective outer retinal bands on spectral-domain optical coherence tomography (SD-OCT), and the size of the ring of increased short-wavelength fundus autofluorescence (SWAF) were analyzed. Correlations between all parameters were evaluated using linear regressions and Pearson correlation coefficient.

Results : The strongest correlation was observed between the SD-OCT and the static Visual Field results. The length of preserved External Limiting Membrane (ELM) was positively correlated on both eyes to the foveal sensitivity at 30° (r=0.93). Positive but weaker correlations were also found between the preserved horizontal ellipsoid zone width and the foveal sensitivity at 10° (r=0.71). However, BCVA measures were poorly correlated with other functional markers such as static or kinetic visual field (respectively r=0.37 and r=0.53 for BCVA (LogMAR) vs the kinetic VF diameter using the II1e isopter or the static VF foveal sensitivity at 30°. This weak correlation was also observed when using structural markers from the SD-OCT and SWAF (r=0.21 and r=0.37 for respectively the correlation of BCVA (LogMAR) / EZ length and BCVA (LogMAR) / horizontal inner diameter of the hyper autofluorescent ring.

Conclusions : Strong correlations were observed between functional and structural parameters evaluated on patients with RP. These results could help defining new composite markers to evaluate the disease severity. They are also of interest when evaluating the efficacy of new therapies for treating patients with a slow disease progression.

This is a 2021 ARVO Annual Meeting abstract.