Evaluation of the effect of the severity of diabetic retinopathy on microvascular abnormalities and vascular density using optical coherence tomography angiography.

Purpose: To quantify and to study the relationship between retinal microvascular changes and different stages of diabetic retinopathy (DR) using optical coherence tomography angiography (OCTA).

Methods: This prospective observational study included the eyes of patients with different stages of DR. OCTA was performed in all eyes using a 9 × 9 mm protocol. We analyzed the superficial and deep retinal capillary plexuses, for the following OCTA parameters: number of microaneurysms (MA), number of intraretinal microvascular abnormalities (IRMA), the total surface of capillary non-perfusion (CNP) areas, and vascular density (VD). The association between those parameters and the severity of DR was studied.

Results: A total of 70 eyes of 45 patients were included. The number of MA in the superficial capillary plexus (SCP) showed a significant association with DR severity (p = 0.03). The number of IRMA and the total surface of CNP areas were associated with the severity of DR in both plexuses (p = 0.019 in the SCP and p = 0.044 in the DCP for IRMA; p < 0.001 in the SCP and p = 0.001 in the DCP for CNP areas). The VD decreased significantly with the severity of DR in the DCP (p = 0.04).

Conclusions: The number of vascular abnormalities and the surface of CNP areas were significantly associated with the severity of DR. The decrease in vascular density in the DCP with increasing disease severity suggests that the DCP is more vulnerable to vascular changes than the SCP. Those parameters might be tools for a future DR severity scale based on OCTA.

Highlights: In addition to its capability of detecting vascular changes in DR non-invasively, OCTA may also serve as a valuable tool to graduate DR.