Neuronal and vascular segregation reveals the impact of systemic hypertension on peripapillary RNFL thickness in diabetic patients without diabetic retinopathy

Abstract

AbstractPurpose: Diabetes (DM) and hypertension (HTN) are common comorbidities in the elderly and can cause damage to the retina, such as neurodegeneration and vascular impairment. The purpose of this study was to determine the impact of HTN on the axonal versus the vascular components of the RNFL thickness in patients with DM without clinical diabetic retinopathy.Methods: Subjects were divided into three groups: healthy controls, 2. patients with DM only, and 3. patients with both DM and HTN. Automated segmentation of peripapillary RNFL is performed, and vascular component is excluded from the segmented RNFL to obtain the thickness measurements and vascular metrics. RNFL with (original) and without the vascular component (corrected) were compared between subjects with diabetes and healthy controls.Results: A total of 279 eyes were included: 182 eyes in controls group, 31 eyes in DM only, and 66 eyes in DM + HTN. The mean original RNFL thickness was significantly thinner in DM + HTN (−3.85 μm, p = 0.014) when compared to controls (103.9 ± 10.1 μm). This relationship between the groups increased significantly when the vascular component is excluded from the RNFL increased (−4.6 μm, p = 0.002). Retinal vessel density was increased in patients with hypertension (14.83 ± 0.32 μm) versus controls (13.97 ± 0.18 μm, p = 0.019) and was correlated with original RNFL thickness (r = 0.189, p = 0.001), but not with corrected RNFL (r = −0.044, p = 0.462). There was no difference in the RNFL thickness between DM only and controls when using either conventional or novel OCT approaches (−3 μm, p ≥ 0.100).Conclusions: The present data indicate that reduced RNFL thickness in diabetic patients without diabetic retinopathy is to a large degree related to impact of hypertension. Changes in peripapillary RNFL thickness as measured with commercial OCT systems may either be the consequence of retinal nerve fibres or reflect changes in retinal vasculature. Accounting for retinal vasculature emphasized the greater decrease in RNFL in HTN individuals than conventional OCT method.