Perturbation of photoreceptor optical characteristics in the early stage of subretinal drusenoid deposits development revealed by adaptive optics imaging

Abstract

Purpose : Subretinal drusenoid deposits (SDD) are extracellular lesions in the subretinal space that have been shown to confer and increased risk for progression to late AMD. Although high-resolution adaptive optics scanning laser ophthalmoscopy (AOSLO) have demonstrated impaired cone photoreceptor reflectivity related to SDD progression, early changes in cone optical properties remain incompletely understood. This study evaluates cone reflectivity during the phase in which SDD were not evident or indeterminate on optical coherence tomography (OCT) using AOSLO.

Methods : Six eyes of 4 patients with intermediate AMD and predominantly SDD underwent multimodal imaging including AOSLO 3-4 times over 3.5 years. Individual SDD were identified by multimodal imaging and graded using an OCT-based 3-stage system at each time point. We evaluated the cross-sectional retinal structure and cone reflectivity at the location in which new SDD developed during the course of follow-up by OCT B-scans and AOSLO.

Results : We identified 32 locations where new dot-form SDD developed during the follow-up period. In the prior assessments at these locations, OCT did not show overt or definitive deposits (stage ≥ 1) between the ellipsoid zone and retinal pigment epithelium complex. However, AOSLO revealed that cones manifested reduced reflectivity in 84% of these regions. The mean time for these sites to develop stages 1, 2, and 3 SDD were 8.9, 13.9, and 25.6 months, respectively.

Conclusions : High-resolution adaptive optics confocal imaging allows for the evaluation of cone photoreceptor optical property alterations associated with SDD development at a phase when these lesions are still not evident on OCT. Our study indicates that cones may demonstrate a reduction in reflectivity 8.9 months before SDDs appear, providing new insight into SDD pathogenesis.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.

 

Figure 1. Reduction of cone photoreceptor reflectivity at the early development stage of subretinal drusenoid deposits (SDD). Although OCT showed indiscernible extracellular material at the baseline between the EZ and the RPE, AOSLO revealed that cone photoreceptors became hyporeflective. At the 7-month visit, a stage-1 SDD appeared and progressed to stage-3 at the 25-month visit.