High resolution adaptive optics imaging analysis of Enhanced S-Cone syndrome with NR2E3 mutation

Abstract

Purpose : Enhanced S-cone syndrome (ESCS) is a rare and unique, slowly progressive autosomal recessive retinal degeneration related to mutation in NR2E3. The histopathological report showed two-fold increased number of Short-wavelength-sensitive cones (S cones) with absence of rods. Also in vivo high-resolution retinal image of ESCS was reported using adaptive optics (AO) scanning laser ophthalmoscopy (Park et al, 2015). However, structural feature in vivo still remains unclear. This study was to characterize the in vivo high-resolution retinal images using spectacle domain optical coherence tomography (SD-OCT) and AO fundus camera of four patients with enhanced S-cone syndrome (ESCS).

Methods : Eight eyes from four cases with ESCS with mutation in NR2E3 (2 males and 2 females, mean age was 52.3 y.o., ranged from 40 to 60 y.o.) underwent ophthalmological examinations including fundus autofluorescence (FAF), SD-OCT （Cirrus 5000TM, Zeiss）and AO fundus camera (rtx1^TM, Imagine eyes, France). Cone density and spacing were measured using 80x80 pixels square images obtained by AO from 1 to 6 degrees temporal and nasal. The results were compared with previously published histological normative data (Curcio et al, 1990) and normal control AO data.

Results : Decimal BCVA of four cases were 20/63 to 20/20. Three cases showed mid-nummular peripheral pigmentary deposition and atrophy in RPE and one case showed subtle pigmentary changes with small hyperpigmented areas within the vascular arcades in FAF. In OCT, multiple disruptions of the interdigitation line and ellipsoid zone was observed in all cases. One eye showed the cysts macular edema. AO images showed some visible photoreceptors at the center of fovea in 7 eyes. At 1 degree from the center of fovea, the cone spacing was 8.77±0.85(μm) and the cone density was (1.59±0.32)×10⁴ (cone/mm²) on average in ESCS. At all eccentricity in the patients with ESCS, the cone spacing were significantly larger and the cone density were significantly lower than that of normative data.

Conclusions : We observed the retinal microstructure on 4 cases with ESCS using AO camera. As all cones were only S-cone in ESCS patients, the cone packing was significantly lower than the normal retina in AO imaging analysis, which related to the OCT findings.

This abstract was presented at the 2019 ARVO Imaging in the Eye Conference, held in Vancouver, Canada, April 26-27, 2019.