Purpose: To evaluate whether macular optical coherence tomography angiography (OCTA) can detect altered vessel density (VD) in the superficial and deep vascular plexus in glaucomatous eyes and to compare the diagnostic utility of the individual VD parameters.
Methods: The macular VD of 135 eyes, comprising 85 eyes diagnosed with glaucoma and 50 healthy control eyes, was examined using two OCTA devices (AngioPlex-Zeiss Meditec, Inc., Dublin, CA, USA, and AngioVue-OptoVue, Inc., Fremont, CA, USA). All study participants had neither vascular pathology, diabetes, nor vasoactive medication. The macular VD was measured at two different levels of segmentation (superficial [SL] and deep [DL] retinal vascular plexus) with a 6 × 6-mm macula scan, and VD was correlated with various structural and functional measurements. In order to test the accuracy of differentiation between eyes with and without glaucoma, we calculated the receiver operating characteristic (ROC) curve and the area under the curve (AUC).
Results: Macular VD was significantly lower in both SL and DL in glaucomatous eyes than in healthy eyes (p = SL < 0.0001; DL = 0.009). There was no significant difference in VD between the SL and the DL (p = 6.60 · 10-18). The greatest reduction of VD in glaucomatous eyes was found in the inferior macular sector. There was no correlation of VD with age or refractive error but moderate to high correlation with intraocular pressure, time of initial diagnosis, mean deviation, ganglion cell complex, peripapillary retinal nerve fiber layer thickness, cup to disc ratio, and rim area. Among the 14 individual features of macular VD, whole VD in the SL had the best diagnostic accuracy (77.6%) as measured by the area under the ROC.
Conclusion: OCTA detects glaucomatous damage by measuring the macular vessel density in the superficial and deep retinal vascular plexus. It can be an additional diagnostic tool to detect glaucoma independently of the optic nerve.
Keywords: Blood flow; Glaucoma; Macula; OCT angiography; Vessel density.