Retinal vessel density and retinal thickness as measured using optical coherence tomography angiography in open angle glaucoma

Objective

To investigate the discriminant function of optical coherence tomography angiography (OCTA) in the diagnosis of primary open angle glaucoma (POAG) and to evaluate the correlation between vessel density, as measured by OCTA, and visual field mean defect (MD) in patients with POAG.

Methods

A case control study was designed.Ninety-five eyes of 54 patients with POAG and ninety-six eyes of 48 healthy subjects in Changsha Aier Eye Hospital were included in this study.The vessel density in the radial peripapillary capillary (RPC) network, the macular vessel density, the ganglion cell complex (GCC) layer thickness, the macular thickness, and the retinal nerve fiber layer thickness were tested for correlation with MD.The aera under the receiver operating characteristic (ROC) curves (AUC), as well as sensitivities at fixed vessel density specificities in the RPC network, and macular regions were analyzed.ROC regression was used to evaluate the effect of covariates on the diagnostic abilities.The study protocol was approved by the Ethics Committee of Changsha Aier Eye Hospital.Written informed consent was obtained from all subjects prior to entering the study cohort.

Results

Compared with the normal control group, the macular area and vessel density in the RPC network were significantly decreased in the POAG group (P<0.001). Also in the POAG group, except for the capillary density inside the disc, all other measurements including the density of superficial capillaries in the macula, the density of deep capillaries in the macula, the density of RPC layers around the optic disc, the average capillary density of the optic disc RPC layer, the capillary density of the optic disc RPC layer (above, below, nasal, and temporal), the thickness of the retinal nerve fiber layer, the thickness of the whole macular layer, and the thickness of the GCC layer of the macula area were positively correlated with the MD value (r=0.586, 0.352, 0.610, 0.592, 0.598, 0.589, 0.445, 0.587, 0.578, 0.530, 0.609; all at P<0.01). The AUCs of vessel densities ranged from 0.623 to 0.927.The highest diagnostic efficiency was the RPC vessel density (whole image), the AUC value was 0.927.

Conclusions

The OCTA parameters have a high diagnostic ability for POAG, except for the capillary density of inside the disc, all other vascular parameters are positively correlated with the MD value.

Optical coherence tomography angiography; Primary open angle glaucoma; Vessel density; Radial peripapillary capillaries; Retinal ganglion cell; Retinal nerve fiber