Multimodal Fundus Imaging in Best Vitelliform Macular Dystrophy

Abstract

Purpose: : To describe the morphological macular features in patients with Best Vitelliform Macular Dystrophy (BVMD) undergoing simultaneous multimodal fundus imaging and compare with those of normal subjects, contributing to the diagnosis and better understanding of disease mechanisms. Previous interpretations based upon histopathology, optical coherence tomography (OCT) or functional tests are somewhat discordant in fundamental issues.

Methods: : Comparative study including 7 patients with BVMD (14 eyes) and 7 age-matched healthy subjects (14 eyes). All participants were submitted to complete ophthalmological examination, fundus photography and standardized multimodal fundus imaging protocol including spectral OCT (SOCT) combined with near-infrared reflectance and blue-light fundus autofluorescence (bFAF).

Results: : In 2 eyes in the "subclinical" stage, SOCT revealed thickening of the middle highly reflective layer (HRL) localized between the photoreceptors’ inner/outer segments junction (inner HRL) and RPE/Bruch’s membrane reflective complex (outer HRL) throughout the macula. In one eye in the "vitelliform" stage, a homogeneous hyper-reflective material on SOCT was observed between the middle HRL and outer HRL; this material presented increased fluorescence on bFAF. The outer nuclear layer (ONL) was thinned in the central macula and subretinal fluid was not identified in these earlier disease stages. In patients of "pseudohypopion" (2 eyes), "vitelliruptive" (8 eyes) and "atrophic" (1 eye) stages, SOCT revealed a variety of changes in the middle and inner HRLs and thinning of ONL. These changes were found to be associated with the level of visual acuity observed. Thickening of the middle HRL was observed beyond the limits of the clinically evident macular lesion in all eyes.

Conclusions: : Multimodal fundus imaging demonstrated thickening of the reflective layer corresponding to the photoreceptors’ outer segments throughout the macula with no subretinal fluid accumulation as the earliest detectable feature in BVMD. Changes detected in the photoreceptors’ reflective layers (middle and inner HRLs) and ONL thinning seemed to be progressive with direct implications for the level of visual acuity impairment observed on disease evolution.

Keywords: imaging/image analysis: clinical • retina • degenerations/dystrophies