Correlation of Macular Vessel Density and Foveal Avascular Zone Metrics in Optical Coherence Tomography Angiography with laboratory and ocular findings in Fabry Patients

Abstract

Purpose : To evaluate macular microvascular changes in patients with Fabry disease (FD) using OCT-A and to correlate with laboratory and ocular findings.

Methods : A total of 76 eyes (38 patients) and 40 eyes of 20 healthy controls were enrolled in this retrospective-prospective study. Macular Vessel Density (MVD) and Foveal Avascular Zone (FAZ) were calculated in 2.9 x 2.9 mm OCT-A images (Heidelberg Spectralis II, Heidelberg, Germany). 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). All scans were analyzed using the EA-Tool (Version 1.0), which was coded in MATLAB (The MathWorks Inc, R2017b). FAZ area (mm²), horizontal and vertical diameters were manually measured in full-thickness scan, SVP, ICP and DCP.

Results : In FD group FAZ was increased in horizontal, vertical SVP and all DCP measurements vs. controls (p<0.05). MVD was higher in all sectors except DCP c1 in FD group vs. controls (p<0.05). MVD of the SVP, ICP and DCP in c1 and SVP and DCP in c2 showed moderate to strong negative correlation with FAZ. MVD in patients with reduced GLA Enzyme activity was decreased in DCP c1 vs. patients with normal enzyme activity. MVD in patients with elevated lysoGb3 activity was increased in DCP full-thickness, c2 and c3, ICP full-thickness and c3 vs. normal lysoGb3 activity. LysoGb3 activity was increased in patients with cornea verticillata (CV) compared with patients without CV (p<0.05). MVD in patients with CV was increased in all ICP and DCP sectors (p<0.02). There was no difference in MVD in patients with and without tortuositas vasorum. Extended results are presented in Fig. 1 and Fig. 2.

Conclusions : FAZ and MVD are increased at first examination in FD patients. Enlargement of FAZ could be a result of an underlying microvascular dysfunction in FD. Increased MVD in FD could be a result of vasodilation caused by an increased endothelium-mediated vascular reactivity due to accumulation of the glycosphingolipids in the vascular endothelium. Cornea verticillata and increased lysoGB3 activity seem to be associated with impaired microvasculature in FD.

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

 

Figure 1. FAZ and MVD in FD group vs. controls

 

Figure 2. Correlation of clinical data and MVD