AbstractPurpose: To study anatomical and vascular changes in the superficial capillary (SCP) and deep capillary (DCP) plexuses in the retina, as well as changes in the choriocapillaris (CC) and foveal avascular zone (FAZ) using optical coherence tomography angiography (OCTA) in type 1 diabetic (DM1) patients without diabetic retinopathy (DR).Methods: We performed a single‐center cross‐sectional descriptive study including 68 eyes of well‐controlled DM1 patients who had been diagnosed at least 10 years prior, and 88 eyes of 88 healthy subjects. All participants underwent a full ophthalmic examination including OCTA using Deep Range Imaging (DRI)‐Triton swept source (SS)‐OCT.Results: six eyes were excluded from the DM1 group after checking the quality of our measurements, resulting in a final sample of 62 eyes. Mean age was 43.79 ± 11.31 and 47.16 ± 15.48 years in the DM1 group and in the control group respectively. There were no differences in VA, EE, AL nor IOP. Statistically significant differences were found in all areas of the SCP, except for the central area, with lower values in DM1 patients. There were differences in all quadrants except the central zone and the superior quadrant in the DCP. In the CC, there were only significant blood flow changes in the central area. We did not find significant differences in the FAZ in neither of the plexuses, but the horizontal FAZ SCP diameter was found significantly different. The anatomical evaluation frequently showed abnormalities such as microaneurysms in both plexuses, FAZ modifications and areas with lack of blood perfusion.Conclusions: Type 1 diabetic patients without DR present microvascular abnormalities with lack of retinal and CC blood perfusion, as well as anatomical changes in retinal blood vessels.