Early Neurovascular Changes in the Retina in Preclinical Diabetic Retinopathy and Relation to Blood Glucose

Abstract Aim: To investigate the changes of retinal optic disc nerve fiber layer thickness and macular blood flow density in preclinical stage of diabetic retinopathy and their relationship with blood glucose. Methods: In this cross-sectional study,97 diabetic patients(total 188 eyes,144 eyes in no diabetic retinopathy group, 44 eyes in mild diabetic non-proliferative retinopathy group ) and 35 healthy people (70 eyes) were enrolled, All the subjects were divided into different group by HbA1c , and underwent ocular examination by optical coherence tomography angiography. We compare optical coherence tomography angiography parameter and retinal nerve fiber layer thickness among different glucose group.Results: The parafoveal vessel density and the temporal retinal nerve fiber layer thickness were lower (P < 0.05) in the diabetic group than in the normal group. The diabetic group showed a higher acircularity index as compared with the normal group. From the normal group to no diabetic retinopathy group and then to mild non-proliferative retinopathy group, vessel density decreased and acircularity index increased (P < 0.001). Foveal vascular density and parafoveal vessel density decreased with the increase of HbA1c. There was a negative correlation between parafoveal vessel density of the deep retinal vascular layer and FBG (P<0.01). The temporal retinal nerve fiber layer thickness decreased among different HbA1c levels groups and was positively correlated with the parafoveal vessel density in superficial retinal vascular layer(P<0.05).Conclusions: This study shows retinal microvasculopathy and neuropathy has been present during no retinopathy. The vessel density of the deep retinal vascular layer was negatively correlated with fasting blood glucose, and the temporal RNFL thickness was positively correlated with the vessel density of superficial retinal vascular layer. These indicators are helpful for endocrinologists and ophthalmologists to detect early diabetic retinal pathological lesions.