Reduced Macular Vessel Density and Capillary Perfusion in Glaucoma Detected Using OCT Angiography

To evaluate retinal vasculature changes in primary open-angle glaucoma (POAG) and whether the functional visual loss correlates with parameters obtained using optical coherence tomography angiography (OCTA).

OCT and OCTA images were collected from 116 POAG eyes and 40 normal eyes in a prospective, cross-sectional observational study. Glaucomatous eyes were further divided into three groups according to a Glaucoma Staging System. Measurements of macular vessel density, ganglion cell complex (GCC), and disk retinal nerve fiber layer (RNFL) thickness were compared among groups.

The macular vessel density, GCC, and RNFL are significantly reduced in POAG compared to normal eyes that also corresponds to the severity of glaucoma (Kruskal-Wallis test with Dunnett's correction; p < 0.0001). Visual field mean deviation correlates significantly with macular vessel density (p = 0.0028, r = 0.3), GCC (p < 0.0001, r = 0.6), and RNFL (p = 0.008, r = 0.36) in POAG. There are significant correlations between GCC and RNFL (p < 0.0001, r = 0.76) as well as macular vessel density (p < 0.0001, r = 0.48). Increased age also correlates with reduced macular vessel density in both normal (p = 0.0002, r = 0.49) and glaucomatous eyes (p < 0.0001, r = 0.48), but a greater proportionate reduction of vessel density is seen in glaucomatous eyes.

Reduced macular vessel density occurs in POAG despite of age-related changes, which also correlates with reductions in RNFL and GCC measurements. OCTA can detect microstructural defects and offers potential to facilitate diagnosis of glaucoma.