Abstract
Purpose :
Retinitis pigmentosa (RP) is a progressive retinal degeneration found in 1 in 4000 in the population. Up to 30% of patients exhibit\ X-linked inheritance, which is most severe. A gene mutation encoding for RP GTPase regulator (RPGR) accounts for 75% of X-linked RP. Optical coherence tomography angiography (OCTA) is a novel non-invasive imaging modality to visualize retinal and choroidal circulation. In this study, we compare the OCTA findings in patients with RPGR RP against patients with non-RPGR RP.
Methods :
This retrospective observational study was approved by the Institutional Review Board with adherence to the Declaration of Helsinki. Subjects underwent genotyping and mutational screening to confirm cause of RP. Normal volunteers were included for control. Complete examinations were conducted in all participants. Fundus photography (FP) and autofluorescence (AF) imaging were acquired. Optical coherence tomography (OCT) and OCTA were obtained as well.
Results :
RPGR RP patients had pigmentary changes within fovea and parafoveal regions. AF imaging showed a ring of hyper-AF surrounding a parafoveal region of hypo-AF with the fovea exhibiting normal AF. This was more apparent in patients with advanced RPGR disease. OCT showed significant retinal and choroidal atrophy. Within the parafovea, there was a loss of outer retinal structures and accumulation of hyperreflective subretinal deposits. On OCTA, parafoveal hyperreflectivity within the superficial and deep retina appeared attenuated. In milder cases, patients showed minimal angiographic disruption within the choriocapillaris and choroid; however, in advanced cases there was significant hyporeflectivity. These features were not observed in non-RPGR subjects, who exhibited attenuated outer retinal vascular perfusion and minimal disruption of choroidal perfusion. Macular OCT from non-RPGR-associated RP patients showed extensive outer retinal atrophy but less prominent choroidal atrophy.
Conclusions :
Our results indicate that RPGR RP demonstrates choroidal vascular disruption. This is in contrast to non-RPGR RP, where choroidal vascular attenuation was minimal. This may be related to the effect that accelerated RPE loss has upon OCTA imaging. OCTA may provide important insight to the extent of ocular damage of RPGR RP and allow for improved management and treatment in upcoming gene therapy trials.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.