Unraveling the differences between Stargardt disease, Central areOlar choroidal dystrophy and geOgraphic atroPhy: the SCOOP study

Abstract

Purpose : Stargardt disease (STGD) and central areolar choroidal dystrophy (CACD) are important mimickers of geographic atrophy (GA). The aim of this study is to report the differences between these 3 conditions using novel imaging modalities and microperimetry (MP).

Methods : Observational, cross-sectional study.
Patients with dry age-related macular degeneration (AMD; 16 eyes), STGD (16 eyes) and CACD (16 eyes) were recruited at a tertiary referral center.
Patients underwent visual acuity (VA), mesopic and scotopic MP (33 stimuli; S-MAIA), high-resolution optical coherence tomography (Hi-Res OCT), fundus autofluorescence (FAF) and OCT angiography (OCTA; PLEX Elite 9000).
Retinal sensitivity (RS) was measured globally, at 0-3° and at 5-7° after excluding areas of retinal pigment epithelium (RPE) atrophy – hyperreflective on infrared images.
Hi-Res OCT images were analyzed for the atrophy type according to CAM reports and status of ellipsoid zone (EZ), external limiting membrane (ELM) and RPE in the surrounding areas. The extension of RPE atrophy was assessed on FAF.
Choriocapillaris (CC) was graded at atrophic areas and at junctional zones on OCTA as absent, rarefied or preserved.

Results : AMD group was older and had higher VA (p<0.05). Eyes with SD and CACD disclosed lower RS under mesopic and red scotopic conditions compared to GA, particularly in the central 0-3° (all p<0.05). No differences were found for what concerns cyan scotopic RS, as AMD eyes had significantly higher cyan-red difference (-7.8+4.8 dB; p<0.001).
Areas of cORA were more frequent in STGD and GA, while cRORA was more prevalent in STGD and CACD (all p<0.05). RPE atrophy was larger in CACD than in GA patients (p=0.03).
At atrophy margins, GA and STGD showed EZ disruption, while CACD eyes had both EZ thickening and focal interruptions. RPE instead appeared separated from Bruch’s membrane (GA), thickened (STGD) or mildly attenuated (CACD).
In SD and CACD, CC was more frequently absent in atrophic areas and rarefied at junctional zone compared with GA (p<0.05).

Conclusions : Our study describes novel imaging and functional characteristics to help differentiating these 3 macular disorders.
Mesopic MP appears a reliable functional endpoint for STGD and CACD. These findings can be of seminal importance as clinical studies on STGD advance and new therapeutic approaches on autosomal dominant dystrophies (CACD) approach.

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