OCT-Angiography as a reliable prognostic tool in laser-treated proliferative diabetic retinopathy: The RENOCTA Study

To quantitatively assess retinal neovascularizations (RNVs) in proliferative diabetic retinopathy (PDR) before and after photocoagulative laser treatment (PLT) using Optical Coherence Tomography Angiography (OCT-A).

Consecutive patients with PDR were examined with fluorescein angiography (FA) and OCT-A before and after PLT. Baseline and after-treatment FA images were quantitatively analyzed to assess both the RNVs area and leakage area. On OCT-A RNVs area, vascular perfusion density (VPD), vessel length density (VLD) and fractal dimension were computed. VPD of the full-retina OCT-A underneath the RNV was determined to evaluate potential laser-induced changes in vascular perfusion.

Fifteen eyes of 13 patients with PDR were enrolled. The mean area of the RNVs was 0.47 ± 0.50 mm² in the baseline OCT-A and 0.32 ± 0.40 mm² in the post-treatment assessment (p = 0.0002). The mean RNV VPD of RNV was 2% ± 4% in pre-treatment and 1% ± 1% for the post-treatment (p = 0.0001). The mean VLD of RNV was 7.26 ± 1.53 at baseline and 6.64 ± 1.65 in the post treatment (p = 0.0002). A significant difference in terms of mean RNVs area and VPD reduction between eyes that needed additional treatment and those that did not (~40% vs ~20%; p < 0.05), was observed. Mean VPD of full-retinal thickness OCT-angiogram was 55% ± 10% for the pre-treatment and 53% ± 8% for the post treatment scan (p = 0.02).

The quantitative OCT-A assessment of laser-induced changes of RNVs can be a useful non-invasive approach for determining treatment efficacy. A reduction of RNVs area or VPD ⩾ 40% might reveal those eyes that won't require additional treatment. Retinal perfusion impairment seemed to progress independently from the treatment.