Optical coherence tomography angiography measured area of retinal neovascularization is predictive of treatment response and progression of disease in patients with proliferative diabetic retinopathy.

Background: The purpose of this study was to evaluate the area of retinal neovascularization in patients with treatment-naïve proliferative diabetic retinopathy (PDR) as measured by optical coherence tomography angiography(OCT-A) as a marker of subsequent treatment response after panretinal photocoagulation (PRP), and to examine if this area correlated with area of retinal neovascularization as measured by fuorescein angiography (FA).Methods: En face OCT-A scans (4.5 ×4.5 mm) of neovascularizations were obtained at baseline (BL) before PRP and at month (M) 3 and M6 after treatment. Progression of PDR were defined as lesion growth (assessed by ophthalmoscopy and wide-feld fundus photo) or increasing leakage by Optos ultra-widefeld FA, and patients were divided into two groups; progression or non-progression. Mann–Whitney U test and Wilcoxon signed-rank test were used to analyse differences between groups and between time points. Areas of retinal neovascularizations (OCT-A and FA) were calculated by algorithms developed in Python (version 3.6.8, The Python Software Foundation, USA).Results: Of 21 eyes included, 14 had progression of disease. Median OCT-A area did not differ between the two groups (progression vs. non-progression) at BL (76.40±162.03 vs. 72.62±94.15, p=0.43) but were statisticallysignifcantly larger in the progression group at M6 (276.69±168.78 vs. 61.30±70.90, p=0.025). Median FA area did not differ in the progression vs. the non-progression group at BL (111.42±143.08 vs. 60.80±54.83, p=0.05) or at M6(200.12±91.81 vs. 123.86±162.16, p=0.62). Intraclass correlation between area by OCT-A and FA was −5.99 (95% CI:−35.28–0.993), p=0.71.Conclusions: In this study of patients with treatment-naïve PDR, we showed that increasing area of retinal neovascularizations measured by OCT-A at M6 indicated progression of disease after PRP treatment. Our results suggest that area by OCT-A refects disease activity and that it can be used as an indicator to monitor the progression of PDR overtime, and to evaluate treatment response six months after PRP