A recent study examined retinochoroidal microvasculature characteristics in patients with ocular hypertension (OHT) and pre-primary open-angle glaucoma (POAG) and found that localized changes indicate early glaucoma pathogenesis.

The study included 180 subjects (38 OHT, 20 pre-POAG and 122 controls). Each subject underwent an ophthalmic examination that included measurements of the retinal nerve fiber layer, retinal ganglion cell layer, inner nuclear layer and Bruch’s membrane opening-minimum rim width.

The researchers also examined macular vascular characteristics on OCT angiography (OCT-A) in the superficial vascular plexus and in the intermediate and deep capillary plexuses. “Recent studies were done by different OCT-A devices, commonly differentiating the microvasculature in two layers, yet only Spectralis OCT-A [used in this study] offers a subdivision into three microvascular layers in macula scans,” the researchers wrote in their paper. “These three vascular plexuses corresponded well with anatomical structures.” In these three regions, the researchers found a significant interaction between diagnosis and sectorial vessel density.

The age-corrected effect on vessel density data also showed a significant difference between the three microvascular layers and diagnosis. Compared with healthy controls, eyes with OHT and pre-POAG had significantly reduced vessel density in all three vascular layers, but the overall mean vessel density differed significantly for these two patient groups only in the superficial vascular plexus. The researchers reported that their findings reflected those in other recently published studies, despite the fact that those studies used OCT-A devices that discerned only two layers.

Importantly, the researchers noted that one limitation of their study was its restriction to white Europeans; their results are only representative of that group. “As ethnicity was seen to influence retinochoroidal microcirculation, the present data should not be seen as overall data,” they emphasized.

Overall, the researchers concluded that eyes with OHT and pre-POAG exhibit regional reductions of macular vessel density, as seen on sectoral analysis of the vascular plexuses, which may influence the retinochoroidal microcirculation in early glaucoma pathogenesis. “The present data argue for a critical role of ocular blood flow, which is present even earlier than neuronal damage of the optic disc,” they noted in their paper.

Hohberger B, Lucio M, Schlick S, et al. OCT-angiography: regional reduced macula microcirculation in ocular hypertensive and pre-perimetric glaucoma patients. PLoS One. February 11, 2021. [Epub ahead of print].