To investigate the microvascular change in diabetic patients with no diabetic retinopathy (DR) and mild nonproliferative DR (NPDR) using optical coherence tomography angiography (OCTA).

We retrospectively reviewed the medical records of 44 eyes of 22 patients with no DR and 34 eyes of 17 patients with mild NPDR. OCTA was performed on a 3 × 3 mm region centered in the fovea and parafoveal areas. The foveal avascular zone (FAZ) and foveal and parafoveal flow density (FD) in superficial and deep vascular plexuses were analyzed using OCTA.

The FAZ of deep capillary plexus in patients with mild NPDR was significantly larger than in patients with no DR ( p = 0.008). The parafoveal deep FD, foveal and parafoveal thickness in patients with no DR was significantly larger than in patients with mild NPDR ( p = 0.013, p = 0.018 and p = 0.003, respectively). Superficial FAZ, superficial foveal FD, superficial parafoveal FD and deep foveal FD were not significantly different between the patients with no DR and those with mild NPDR.

OCTA allows detection of deep FAZ enlargement, reduction in parafoveal deep FD as well as foveal and parafoveal thickness in patients with mild NPDR compared with patients with no DR.