The 300μm-wide region near the foveal avascular zone (FAZ) (FD300) experiences decreased blood flow density, and increased FAZ perimeter and acircularity index (AI)  in patients with early diabetic retinopathy (DR), according to research published in the Journal Français d’Ophtalmologie. These variables could serve as biomarkers for DR, and are detectable upon optical coherence tomography angiography (OCTA) evaluation.

Researchers assessed 122 eyes of 94 patients with type 2 diabetes. They stratified participants into 3 groups based on DR type: no diabetic retinopathy (NDR, 42 eyes, 31 patients), mild non-proliferative DR (mild NPDR, 40 eyes, 33 patients), and moderate NPDR (40 eyes, 30 patients). They also included a control group consisting of 40 eyes of 40 healthy patients. 

The team measured blood-flow densities of the superficial capillary plexus (SCP) and deep capillary plexus (DCP)/FD300 and obtained FAZ area, FAZ perimeter, and AI.


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Investigators noted that FAZ perimeter and AI were higher in patients with type 2 diabetes compared with the control group, while blood-flow densities at the SCP, DCP and FD300 decreased (P <.05). The blood-flow densities of the SCP, DCP, and FD300 in the macular zone of patients with DR decreased with advanced stages of DR, and the FAZ perimeter and AI increased (P <.05). The team observed no collinearity. They noted the highest area under the curve of FD300 associated with early DR with a sensitivity and specificity of 84.13% and 67.19%, respectively. An AI with a threshold of 1.05 demonstrated the best specificity (87.84%) and sensitivity (73.62%) for predicting early DR.

“OCTA can detect the reduction in the blood flow densities at the SCP and DCP in the macular zone in NDR patients, as well as increases in the FAZ perimeter and AI and the irregular FAZ area in mild NPDR patients,” according to the researchers. “The blood flow densities at the SCP, DCP and FD300 can be regarded as sensitive indicators for the evaluation of retinal microcirculation damage in diabetic patients, which are worthy of clinical promotion.”

This study was limited by a small sample size. 

Reference

Zhao S, He J, Qiu M, Liang X. Changes of blood flow in macular zone of patients with diabetic retinopathy at different stages evaluated by optical coherence tomography angiography. J Fr Ophtalmol. Published online May 13, 2022. doi:10.1016/j.jfo.2022.01.010.