Optical Coherence Tomography Angiography for the Evaluation of Retinal Vasculature in Fabry Disease: Our Experience and Review of Current Knowledge

Abstract

Purpose: Optical coherence tomography angiography (OCTA) is a non-invasive and objective tool for the evaluation of the retinal microvascular changes in Fabry disease (FD). We investigated changes in retinal vasculature in FD patients, and the possible correlation with systemic parameters, by using OCTA, and reviewed the current status of literature. Methods: Thirteen FD patients (eight females, five males, mean age 49.85 ± 14.7 years) were compared with 13 age- and sex-matched healthy controls. OCTA 3 × 3 mm macular scans were performed in all subjects. We evaluated the vessel density and vessel perfusion in distinct macular areas (whole, inner, and outer) of both the superficial capillary plexus (SCP VD and SCP VP) and of the deep capillary plexus (DCP VD and DCP VP). We also evaluated the foveal avascular zone (FAZ) metrics (area, perimeter, and circularity), and correlation between systemic and OCTA parameters. A literature review on the current understanding of OCTA in FD is then presented. Results: FD patients showed significantly lower SCP VD values in the whole area (17.37 ± 2.08 mm^-1 vs. 18.54 ± 1.21 mm^-1; p-value 0.022), as well as in the outer area (17.46 ± 2.10 mm^-1 vs. 19.08 ± 1.14 mm^-1; p-value 0.002), but not in the inner. Even the DCP VD was significantly lower in all the imaged areas: whole (17.75 ± 3.93 mm^-1 vs. 19.71 ± 1.20 mm^-1; p-value 0.024), outer (18.25 ± 4.17 mm^-1 vs. 20.33 ± 1.20 mm^-1; p-value 0.023), and inner (19.54 ± 4.17 mm^-1 vs. 21.96 ± 1.55 mm^-1; p-value 0.011). There were no significant differences in vessel perfusion parameters (both SCP VP and DCP VP ones) and FAZ. No significant correlations were found between the OCTA parameters and systemic parameters (maximal left ventricular wall thickness and glomerular filtration rate) in FD patients. Conclusions: OCTA can be considered as a promising non-invasive tool, which enables a quantitative evaluation of retinal vascular involvement in FD, despite the varying data reported in literature. Our results support the use of OCTA as an objective tool to evaluate retinal vascular abnormalities in FD. The utility of OCTA in FD needs to be validated by longitudinal studies taking into account the overall progression of the disease.

Keywords: Fabry disease; OCTA; optical coherenc tomography angiography; vascular density; vascular perfusion.

Figure 1

Optical coherence tomography angiography (OCTA) 3 × 3 scans. Scan of the superficial capillary plexus in a healthy control (on the left) and in a patient with Fabry disease (on the right).

Figure 2

Early Treatment Diabetic Retinopathy (ETDRS) grid centered on the fovea. (A) Division of the macular area into nine subfields: 1 = center, 2 = inner superior, 3 = inner right, 4 = inner inferior, 5 = inner left, 6 = outer superior, 7 = outer right, 8 = outer inferior, and 9 = outer left. (B) The fovea is defined as the area within the central 1-mm ring of the ETDRS grid. The surrounding ring with an inner diameter of 1 mm and an outer diameter of 3 mm is considered as the inner ring. The ring with an inner diameter of 3 mm and an outer diameter of 6 mm is considered as the outer ring. The whole includes the fovea and the inner and outer rings.

Figure 3

Optical coherence tomography angiography scans (3 × 3 mm) in patients with Fabry disease. Rarefaction of the vascular texture of both the superficial capillary plexus (A,C,E) and the deep capillary plexus (B,D,F) can be observed.

Figure 4

Optical coherence tomography angiography scans (3 × 3 mm) at the superficial capillary plexus in patients with Fabry disease. (A–D) Morphological alterations of the foveal avascular zone with irregular borders and sudden changes in the direction of the vessels with perifoveal loops can be observed.

Figure 5

Retinal vessel density in patients with Fabry disease and normal control group. Vessel density in both the whole superficial capillary plexus (SCP) (A) and the whole deep capillary plexus (DCP) (B) is lower in the group of patients affected by Fabry disease.