Retinal Microcirculation in Predicting Diabetic Nephropathy in Type 2 Diabetic Patients without Retinopathy

<b><i>Purpose:</i></b> To evaluate retinal thicknesses and retinal microcirculation in healthy controls and in diabetic patients with or without microalbuminuria. <b><i>Methods:</i></b> Eighty-six diabetic patients without diabetic retinopathy (DR) (44 normoalbuminuric, 42 microalbuminuric) and 51 healthy controls were enrolled in this cross-sectional, prospective study. Optical coherence tomography (OCT) and OCT angiography (OCTA) were performed. Correlations between OCTA parameters with mean urinary albumin levels were evaluated. <b><i>Results:</i></b> The mean vessel densities of superficial capillary plexus (SCP), whole disc, and peripapillary area were significantly decreased in patients with microalbuminuria compared to patients with normoalbuminuria and controls (<i>p</i> &#x3c; 0.05 for all). The mean vessel density of deep capillary plexus was significantly reduced in patients with microalbuminuria compared to controls (<i>p</i> &#x3c; 0.05 for all). There were no significant differences in retinal thickness between groups (<i>p</i> &#x3e; 0.05). Both duration of diabetes and urinary albumin levels were significantly and moderately correlated with mean vessel density of whole SCP in diabetic patients (<i>r</i> = 0.330, <i>p</i> = 0.021; <i>r</i> = 0.356, <i>p</i> = 0.017, respectively). <b><i>Conclusion:</i></b> Diabetic eyes without clinically detectable DR show impaired retinal microcirculation. Microalbuminuria is associated with alterations of retinal microcirculation in diabetic patients without DR. Evaluation of retinal microcirculation is likely useful for detecting early changes related to microvascular complications in type 2 diabetic patients.