Spatial Relation between Hyperreflective Foci and Vascular Network in Eyes with Cystoid Macular Edema

Abstract

Purpose : Hyperreflective foci (HF) on OCT images may be associated with retinal inflammatory responses and represent activated microglia or lipoprotein exudation.^a,b Using volume rendering of OCT-reflectance (OCT-R) and OCT-angiography (OCT-A), we evaluated the spatial relation between HF and the neighboring vascular network in eyes with cystoid macular edema.

Methods : Seven patients with cystoid macular edema due to diabetic retinopathy, retinal vein occlusion, or hemangioblastomas were imaged using a clinical SD-OCT system (Avanti RTVue-XR; Optovue). Ten 3x3mm scans centered at the fovea were obtained and averaged. OCT-R (Fig. A) showing the structural features (e.g. HF and cystoid spaces) and OCT-A (Fig. B) showing the perfused vasculature were flattened at the Bruch’s membrane and merged into a single volume using ImageJ (NIH, MD, USA). To better visualize the spatial relation between HF, cystic structures, and vascular network, the merged OCT-R and OCT-A volume was 3-D rendered (Fig. C) using MIPAV (Medical Image Processing, Analysis, and Visualization, NIH, MD, USA).^c

Results : Diffused and/or clustered HF were identified in all patients with cystoid macula edema. Distinct HF were found within the walls of cystic structures and within the cystoid spaces (Fig. C). Relatively weak OCT-A signal underneath the locations with HF aggregation was observed due to shadowing effect. Perivascular HF were identified around both perfused and non-perfused blood vessels.

Conclusions : We demonstrated three-dimensional observation of HF, cystic structures, and vascular network using a merged OCT-R and OCT-A volume. Assessing spatial relation between these structural and examining associated functional abnormalities may provide insight on the pathophysiology of cystoid macular edema and its progression.
^aPMID: 29392317; ^bPMID: 24386645; ^cPMID: 26428608

This is a 2020 ARVO Annual Meeting abstract.