Optical coherence tomography angiography findings of type 1 diabetic patients with diabetic retinopathy, in comparison with type 2 patients.

Abstract

To compare optical coherence tomography angiography (OCT-A) parameters between type 1 and type 2 diabetic patients with diabetic retinopathy (DR). A total of 70 patients with type 1 diabetes and 70 with type 2 diabetes were retrospectively analyzed. DR was graded as no DR, mild nonproliferative DR (NPDR), moderate NPDR, severe NPDR, and proliferative DR (PDR). Using OCT-A, the foveal avascular zone (FAZ) area (mm2) and vascular density (VD) (%) were calculated in the superficial capillary plexus (SCP) and deep capillary plexus (DCP). In both type 1 and 2 diabetes patients, the FAZ area (mm2) in both capillary plexuses (CP) increased with DR progression, whereas the VD (%) progressively decreased. The changes in the FAZ area and the VD were significantly greater in the DCP than in the SCP in both types of diabetes patients(p < 0.001). In the analysis of decreasing slope of the VD in the DCP, attenuation was not significant until severe NPDR stage but then abruptly decreased when it progressed to PDR stage in type 1 diabetes. In type 2 diabetes, the DCP VD decreased gradually as DR stage progressed. As DR progression, the increasing in FAZ area and the decreasing in VD are more severe in the DCP than in the SCP in both types of diabetes. In type 1 diabetes eyes, they were remained in relatively healthy until it gets to the advanced stage of DR, while the gradual deterioration of FAZ area and VD was found from the early stage to the advanced stage of DR in type 2 diabetes.