Quantitative Optical Coherence Tomography Angiography (OCT-A) Analysis of Macular Vascular Structure and Foveal Avascular Zone in Glaucoma

Abstract

Purpose : The aim of this study is to evaluate quantitative characteristics of the macular vessel density (VD) and the foveal avascular zone (FAZ) in glaucoma using optical coherence tomography angiography (OCT-A).

Methods : 25 eyes with primary open angle glaucoma (POAG) and 12 eyes of healthy participants were enrolled retrospectively. All participants’ functional visual field (Octopus 101, Haag Streit®) and structural OCT Spectral-Domain (Heidelberg-Spectralis®) Retinal Nerve Fiber Layer Thickness (RNFLT) were assessed. OCT-A (Heidelberg-Spectralis®) was performed on a 15x10 degrees macular region centered on the fovea. OCT-A scans were processed in one-step analysis with MATLAB software (script developed by the autores) and automatically graded to define FAZ parameters. The parafoveal VD in the superficial and deep retinal vascular plexus (SVP and DVP) were analyzed by quadrant and circular segmented zones. FAZ parameters included area, axis length, diameter, perimeter, and circularity index (defined as a function of the perimeter and the area of the shape).

Results : FAZ - Major Axis Length (p=0.02), Area (p=0.04), Equivalent Diameter (p=0.04) and Perimeter (p=0.04) were significantly larger in glaucoma than in control group. For SVP and DVP, the average macular total VD were lower in glaucoma patients compared to control group (p<0.01; p<0.01). Additionally, the inner circular region (p=0.04; p<0.01 respectively for SVP and DVP) and all quadrants but North had a lower VD in glaucoma group when compared with control group. Assessment of the total VD successfully predicted RNFLT (p<0.001) and was significantly associated with the probability of having glaucoma (p=0.009).

Conclusions : OCT-A parameters, namely the FAZ morphology and the macular VD, were associated with glaucomatous functional and structural changes. The macular VD showed a considerable diagnostic value. It may be a novel biomarker, representing microvascular network disruption of the macular perfusion in glaucoma.

This is a 2020 ARVO Annual Meeting abstract.

 

Macular OCT-A output after MATLAB processment. Microvascular network disruption in eyes with glaucoma and advanced glaucoma compared with healthy eyes.