Abstract
Purpose :
Dark cones have been reported and may be an early sign of retinal disease progression in childhood-onset Stargardt disease [Song et al. JAMA Ophthalmol. 2015; 133(10)]. The aim was to compare outer-retinal structure across multiple retinal locations to identify early structural changes in adult-onset ABCA4 Stargardt disease utilizing multi-modal imaging
Methods :
Seven adult patients (3 males; 29–69 y) with genetically-diagnosed adult-onset Stargardt disease and 15 healthy controls (7 males; 23–74 y) were imaged with confocal and non-confocal Adaptive Optics Scanning Light Ophthalmoscopy (AOSLO), optical coherence tomography (SD-OCT), fundus infrared (FIR) and autofluorescence (FAF). After correcting for retinal magnification, montages of AOSLO images were aligned with FIR, FAF and OCT scans to explore changes in retinal structure across imaging modalities. Retinal layer-thicknesses were extracted from semi-automatically segmented OCT images at regions with clinically normal appearance on FIR and FAF and intact outer retinal layers on OCT, peripheral to the atrophic area. Retinal thickness (RT) and outer retinal layer thickness (ORL) at 2.5 mm nasal to the foveal center and at retinal locations with dark cones as seen on confocal AOSLO, but with otherwise clinically normal appearance, were compared with the same regions in controls
Results :
Patients had visual acuity of -0.02–0.98 logMAR. Foveal structure, as seen on OCT and non-confocal AOSLO, was highly variable. A contiguous cone inner-segment mosaic was seen in the foveal center in three patients, while foveal atrophy or a few remnant foveal cones were observed in four patients. Six of these had intact retinal layers in the region 2.5 mm nasal to the foveal center, but with thinner RT and ORL than in controls (RT: 259±39 µm vs. 306±15 µm, p < 0.001; ORL: 102±37 µm vs. 133±6 µm, p = 0.003). Dark gaps of non-waveguiding cones were seen on confocal AOSLO in six regions with clinically normal FIR, FAF and OCT appearance in three patients. Non-confocal AOSLO revealed an intact cone inner-segment mosaic. Thinner RT and ORL than controls (z-scores < -2) were only observed in two of the analyzed regions
Conclusions :
The results indicate that dark cones may be a first sign of progression in adult-onset Stargardt disease as these are observed in locations with otherwise normal appearance and outer-retinal thickness
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.