Multimodal Imaging in Best Vitelliform Macular Dystrophy

Abstract

Purpose : To assess RPE integrity within and outside the vitelliform lesion by analysis of short wavelength (SW-AF) and near-infrared fundus autofluorescence (NIR-AF) quantitative analysis and spectral domain optical coherence tomography (SD-OCT).

Methods : Fourteen patients heterozygous for BEST1 were recruited. Each patient had a complete ophthalmologic evaluation and the images were acquired. Best Vitelliform Macular Dystrophy (BVMD) patients were staged according to OCT findings. Quantitative autofluorescence (qAF) imaging was performed using SW-AF images generated by Spectralis HRA+OCT (Heidelberg Engineering, Germany) equipped with an internal fluorescent reference. Mean gray levels were determined in eight concentric segments at an eccentricity of approximately 7 to 9° from the fovea and the outer contour of the high AF signal was used as the outer limits of the lesion. An HRA2 (Heidelberg Engineering, Germany) (787 nm; sensitivity of 96) was used to capture NIR-AF images that were saved in the non-normalized mode. ImageJ (Microsoft Java 1.1.4) was used to quantify the NIR-AF image. SD-OCT images were also acquired with the Spectralis HRA+OCT.

Results : We analyzed 28 eyes from 14 patients with BVMD. One patient was excluded from the quantitative analysis because lesion size and position precluded measurements outside the lesion. SW-AF images within the lesion varied with the stage of disease from normal in pre-clinical to a mottled pattern in vitelliruptive stage. NIR-AF imaging revealed an area of reduced fluorescence in pre-vitelliform stage while in vitelliruptive stage puncta of elevated signal were present. In both SW and NIR-AF images the atrophic stage had reduced signal. Importantly, non-lesion qAF was within the 95% confidence intervals for healthy eyes, independent of the stage of the disease. Similarly, the NIR-AF intensity measurements outside lesion were comparable to the control eyes. SD-OCT scans revealed a fluid-filled detachment between the interdigitation zone (IZ) and the hyperreflectivity band attributable to RPE/Bruch’s membrane.

Conclusions : Mutations in BEST1 are not associated with increased levels of SW-AF outside the vitelliform lesion. The high levels of SW-AF within the vitelliform lesion likely reflect the inability of RPE to phagocytose shed outer segment membrane due to the fluid-filled separation between RPE and photoreceptor cells together with progression photoreceptor cell impairment.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.