Novel microscopic foveal pit pathology in multiple sclerosis revealed with adaptive optics ophthalmoscopy

Abstract

Purpose : Multiple sclerosis (MS) is characterized by inflammation and axonal degeneration, affecting retinal ganglion cells and their axons, as well as retina microvasculature. However, these changes do not fully account for the visual function deficits reported by multi-focal electroretinogram (Landau, et al. IOVS 2018; 59(1):549-60). In this study we report the presence and appearance of novel microscopic structures in the foveal avascular zone (FAZ) that may contribute to visual dysfunction in MS.

Methods : One eye without history of optic neuritis in each of 7 female subjects with stable multiple sclerosis (4 relapsing-remitting, 3 secondary progressive, age 56±15 yrs) underwent standard clinical examination, followed by adaptive optics scanning light ophthalmoscopy (AOSLO). Simultaneous reflectance AOSLO confocal and non-confocal split-detection image sequences of the fovea were acquired using 790 nm light. Registered images were averaged and tiled to cover the FAZ, where the Feret’s diameter and area of manually segmented structures were recorded.

Results : Abnormal hyper-reflective structures (Fig. 1) were observed at the bottom of the foveal pit within the FAZ in both confocal and non-confocal split-detection images of 5 subjects. Their diameter ranged from 9.6 to 94.7 µm and area ranged from 48 to 3416 µm². The structures had a raised, textured appearance, with visible sub-structures within them. These structures appeared to cast a shadow at the corresponding location over the photoreceptor mosaic. Additionally, foveal punctate reflectivity, previously seen in normal and diseased retinas (Scoles, et al. IOVS 2014; 55(7):4015-29), was observed in the confocal images of 3 eyes. Unlike the larger structures, these seem to be largely absent in the corresponding split-detection images, and do not appear to cast shadows on the photoreceptor mosaic.

Conclusions : Previously unreported microscopic features, not detectable with clinical examination, were observed in the foveal pit of 5 out of 7 MS subjects. Monitoring these structures may be useful as a biomarker for evaluating ocular disease progression in MS.

This is a 2020 ARVO Annual Meeting abstract.

 

Reflectance confocal (A,B) and split-detection (C) AOSLO images of the foveal pit bottom (B,C) and photoreceptor mosaic (A) at the corresponding retinal location showing novel structures (arrows) in a multiple sclerosis subject.