Effect of hypertension on retinal microvasculature in type 2 diabetic patients without diabetic retinopathy by OCTA

Objective To assess the effect of hypertension (HTN) on retinal microvasculature in patients with type 2 diabetes mellitus (T2DM) without diabetic retinopathy (DR) through optical coherence tomography angiography (OCTA). Methods A total of 154 eyes from 154 T2DM patients without DR who were admitted to Departments of Endocrinology and Cardiology, the Affiliated Hospital of Xuzhou Medical University from March 2023 to March 2024 were included. According to the presence of hypertension in these T2DM patients and the severity of hypertension, the patients were categorized into three groups: a T2DM group (n=47), a T2DM with mild to moderate HTN group (n=55), and a T2DM with severe HTN group (n=52). OCTA was used to perform blood flow imaging scans of the macular area, and the changes in various parameters in the macular area of the retina were analyzed among the groups. Results Compared to the T2DM group, the other two groups exhibited decreases in superficial capillary plexus (SCP) density in the parafoveal region of the 6 mm×6 mm macular area across all quadrants (P<0.05), as well as decreases in the temporal and superior SCP density of the perifoveal region (P<0.05). The density of deep capillary plexuse (DCP) in the temporal, superior and nasal side of the parafoveal region and the temporal and superior side of the perifoveal region decreased (P<0.05). Compared to the T2DM with mild to moderate HTN group, the T2DM with severe HTN group showed reduction in SCP density in the parafoveal region of the macular area across all quadrants (P<0.05) and in the temporal and superior SCP density of the perifoveal region (P<0.05), as well as decreases in DCP density in the temporal, superior, and nasal areas of the parafoveal region and the temporal and superior sides of the perifoveal region (P<0.05). Furthermore, compared with the T2DM group, the area and perimeter of foveal avascular zone (FAZ) increased, and FD-300 decreased in the other two groups (P<0.05). The T2DM with severe HTN group showed a larger FAZ area, longer perimeter and a lower FD-300 than the T2DM with mild to moderate HTN group (P<0.05). Conclusions OCTA indicates that T2DM patients without DR who have concomitant hypertension experience more severe microvascular damage in the macular area of the retina, with higher blood pressure leading to greater damage. OCTA has significant clinical value in the examination, diagnosis, and follow-up of T2DM patients with concomitant hypertension.