Optical coherence tomography angiography value for detection of early retinal microvascular changes in systemic hypertension

Abstract

Purpose The aim of this study was to assess the macula and optic disc vessel density (VD) and perfusion and the anatomical alterations at the fovea and optic nerve in chronic treated hypertension (HTN) patients who exhibited no signs of hypertensive retinopathy using optical coherence tomography angiography (OCTA). Patients and methods This is a prospective case–control study that included 37 participants. They were subdivided into two groups: the hypertensive group that included 22 patients (mean age=51.9±5.9 years), with no clinically evident signs of hypertensive retinopathy, and the control group that included 15 individuals (mean age=48.8±3.7 years) with no known history of HTN or other chronic systemic diseases. OCTA scans covering a 6.0×6.0 mm area for the macula and a 4.5×4.5 mm region for the optic nerve head were performed to evaluate the VD, the foveal avascular zone area, macular thickness, and retinal nerve fiber layer (RNFL) thickness. The correlation of the VD measurements with the RNFL thickness was evaluated. Results The hypertensive patients exhibited a significantly lower overall mean macular VD (45.8±6.0) compared to the control group (48.5±2.9, P=0.017). In addition, they exhibited a significantly lower superficial VD in the superior hemifield (46.4±5.3 and 48.6±2.9, respectively, P=0.030). On the other hand, the deep vascular density in the superior hemifield showed no significant difference between the two groups. In addition, the hypertensive patients were found to have a significantly lower average RNFL thickness (103.2±17.8 μm) compared to the control group (117.1±14.1 μm, P=0.001), with specific statistically significant reductions in the superior (P=0.002) and inferior (P=0.004) sectors. Although the central ganglion cell-inner plexiform layer thickness did not reach statistically significant difference between the two groups (HTN: 50.7±12.0 μm vs. control: 55.7±8.8 μm, P=0.055), the hypertensive group exhibited statistically significant reductions in the ganglion cell-inner plexiform layer thickness in the superior (P<0.001), inferior (P=0.002), nasal (P=0.003), and temporal (P=0.001) sectors compared to the controls. There was no statistically significant difference in the size of the foveal avascular zone between the two groups. Conclusion OCTA revealed subclinical alterations in the retinal microvasculature parameters among the hypertensive patients without clinical signs of hypertensive retinopathy, in comparison to normotensive individuals.