OCTA and Microperimetry Changes Preceding the Appearance of Diabetic Retinopathy in Patients with Type 1 Diabetes.

Purpose: to evaluate changes in retinal microvasculature and sensitivity (RS) preceding the appearance of diabetic retinopathy (DR) among patients with type 1 diabetes (T1D).

Methods: in this observational cross-sectional cohort study, vascular parameters measured by OCTA and RS evaluated by microperimetry were assessed in patients with T1D without DR (no-DR), T1D with mild DR (m-DR), and healthy controls.

Results: Sixty-two eyes of 31 patients with T1D and 40 eyes of 20 healthy patients were included. OCTA examinations did not yield any significant differences in terms of perfusion density (PD), vascular density (VD), foveal avascular zone (FAZ) area, FAZ perimeter or FAZ circularity between patients with diabetes (no-DR m-DR). However, comparisons between healthy controls and patients with diabetes (both no-DR and m-DR groups) revealed statistically significant differences in PD, VD, and FAZ area. Similarly, no significant differences were observed between no-DR and m-DR groups regarding RS, gaze fixation stability (GFS), or macular integrity (MI). Nevertheless, mean RS and MI were significantly impaired in patients with T1D, both in no-DR and m-DR groups, compared to healthy controls. A statistically significant positive correlation was observed between RS and PD and between FAZ area and RS.

Conclusion: although no differences were found between patients with diabetes without DR and those with mild DR, these patients already demonstrated some degree of retinal impairment, both structural and functional, when compared to healthy controls. Our data support the hypothesis that neurodegeneration occurs together with microvascular damage at early stages of diabetes.