The relationship between carotid intima-media thickness and microvascular changes in retinal zones and optic disc in patients with type 1 diabetes mellitus.

PURPOSE The aim of this study was to detect early retinal vascular changes with optical coherence tomography angiography (OCTA) in type 1 diabetes mellitus (T1DM) patients without diabetic retinopathy and to evaluate the correlation of the results with carotid intima-media thickness (IMT). DESIGN This is a case-control and cross-sectional study. METHODS This study included 38 adult patients with T1DM, and 38 age and gender-matched healthy controls. Retinal and optic disc (OD) measurements were taken using OCTA. The carotid artery IMT of each patient was measured using Doppler ultrasonography. Superficial capillary plexus (SCP) and deep capillary plexus (DCP) vessel density, foveal avascular zone (FAZ), non-flow area (NFA) and foveal density (FD) were analysed in the fovea centred 6 × 6 mm macular area. The superficial capillary plexus and DCP were also scanned centred on the peripapillary region. The correlations between OCTA measurements and carotid IMT, duration of DM and haemoglobin A1c levels in patients with T1DM were evaluated. RESULTS The mean values for carotid IMT were significantly higher in diabetic patients than in controls (p < 0.001). The mean values for vessel density SCP, DCP and OD were significantly lower in the diabetic group (p < 0.05). There were correlations between the carotid IMT and duration of T1DM and the evaluated parameters of OCTA. CONCLUSION Microvascular changes in the SCP and DCP in patients with T1DM without DR offer important data. OCTA can be used to detect early microvascular changes in patients with T1DM without DR. In addition, a relationship was found between SCP vascular dropout and carotid IMT.