A software for quantification of vessel density in glaucoma: An OCT-Angiography study

To assess the capillary vessel density in the peripapillary region of glaucoma patients in comparison to controls using automated software.

We performed an observational, cross-sectional case-control study with 72 eyes of glaucoma patients (with strict selection criteria) and 30 age-matched healthy controls. We used an optical coherence tomography angiography device (Triton, Topcon) with scans of 4.5×4.5mm centered on the optic nerve head, excluding images of poor quality. Since this device does not quantify vessel density, we wrote software (with Visual Studio©) that allowed us to remove large blood vessels and quantify the capillary density in the peripapillary region. We tested the ability of OCT-A to differentiate glaucoma from controls using the receiver operating characteristic curve (ROC). We also verified whether VD was correlated with visual field mean deviation.

VD was significantly lower in glaucoma than in controls, notably the whole-image VD of 72.45±7.45% in glaucoma and 77.87±3.77% in controls (P<0.001). VD values were correlated with visual fields (Spearman correlation of 0.33; P 0.0017). ROC was moderate (color VD of 0.629±0.143), but better than that of the visual field (0.229±0.077) or the retinal nerve fiber layer thickness assessed by OCT (0.326±0.064).

This software is useful for quantifying vessel density at the optic disc, peripapillary and capillary levels and for documenting glaucomatous changes in vascularization. OCT-A might be useful in diagnosis of glaucoma.