Cysts across areas with preserved outer retinal layers challenge cone detection with adaptive optics ophthalmoscopy in retinitis pigmentosa

Abstract

Purpose : To observe features of interest such as cysts in retinitis pigmentosa (RP) with high resolution imaging and quantify cone density in RP.

Methods : A 33-patient subset (17 female, age 50 +/- 13 years old) of a cohort of RP recruited to a multi-centric natural history study, who had undergone standard clinical imaging including OCT (Spectralis, Heidelberg), were imaged over 1-3 visits spanning a two-year period with an adaptive optics camera (PSI Corp, Andover MA) combining confocal/multi-offset scanning laser ophthalmoscope (AO-SLO) and optical coherence tomography (AO-OCT).

Results : The presence of retinal cysts complicated cone quantification from AOSLO images. In multi-offset AOSLO, we observed patients with only cones visible (29%), only cysts (16%), a mix of both not overlaid (23%) or a mix of both overlaid (29%) where cysts caused a lensing effect which could falsify cone counts. Overall, cones were therefore only quantifiable in 52% of patients. Multi-offset AOSLO detected cysts in 68% of subjects while clinical OCT detected them in 60% of subjects. Cystic changes were consistently seen only in zones where the cones still were present. Cysts were located in the inner nuclear layer, as determined from clinical OCT and AOOCT. Multi-offset AOSLO presented the best contrast of cyst borders, permitting quantification of their sizes (between 280 and 5830 µm2).

Conclusions : Overlying cysts prevented quantification of underlying cone density. Studies assessing cone density as a biomarker of progression should take into account cyst presence, e.g by quantifying only in zones of visible cones. Multi-offset AOSLO is best suited to assess the effect of various treatments on both cyst size and underlying cone structure.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.