Macular Vessel Density and Foveal Avascular Zone Metrics Using Optical Coherence Tomography Angiography in Fabry Disease. Long Term Follow Up

Abstract

Purpose : To investigate the long-term changes in macular microvasculature and explore a reliable retinal biomarker of Fabry Disease (FD).

Methods : Retrospective-prospective study of 26 eyes with FD (13 patients, 9 treated, 4 untreated) followed up to 48 months (mean 24, range 8-48). OCT Angiography (OCT-A) images (2.9x2.9 mm) were obtained using Heidelberg Spectralis II (Heidelberg, Germany). All OCT-A scans were analyzed using EA-Tool (Version 1.0), which was coded in MATLAB (The MathWorks, Inc., R2017b). Macular Vessel Density (MVD) was measured in three layers: Superficial Vascular Plexus (SVP), Intermediate Capillary Plexus (ICP), and Deep Capillary Plexus (DCP) in circular sectors (c1, c2, and c3). The Foveal Avascular Zone (FAZ) area (mm²), horizontal and vertical diameters were manually measured in full-thickness scan, SVP, ICP and DCP.

Results : MVD decreased over time in SVP and ICP in c2 and c3 and in all sectors in DCP in FD patients (p<0.04). MVD reduction was predominantly seen in treated FD patients. FAZ full-thickness scan area and horizontal diameters increased at follow up in FD patients compared to baseline (p<0.03). FAZ at follow-up was larger in full-thickness scans and ICP in untreated vs. treated FD patients (p<0.03). Correlation analysis showed a moderate negative correlation between MVD in the inner most circle of SVP and DCP and FAZ in treated FD patients (|r|>-0.6). Extended results of MVD and FAZ follow up in all and treated vs. untreated patients are presented in Fig. 1 und Fig. 2.

Conclusions : This is the first long term follow-up OCT-A study in FD patients. MVD decreased in peripheral circle and deeper layers in follow-up in FD patients. Meanwhile FAZ increased at follow-up in the FD group. These changes over time are most likely linked to the vascular remodeling during the course of the disease. The reduction of MVD was predominantly seen in treated FD patients. This could be a result of enzymatic replacement therapy and could be potentially used as a reliable biomarker for monitoring the treatment of the disease. A baseline examination of MVD und FAZ before treatment initiation is meaningful. Larger studies are needed to establish the use of MVD und FAZ as biomarkers for treatment monitoring.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.