Optical coherence tomography angiography assessment of 577 nm laser effect on severe non-proliferative diabetic retinopathy with diabetic macular edema

To quantitatively evaluate the effect of the combined use of 577-nm subthreshold micropulse macular laser (SML) and multi-point mode pan retinal laser photocoagulation (PRP) on severe non-proliferative diabetic retinopathy (NPDR) with central-involved diabetic macular edema (CIDME) using optical coherence tomography angiography (OCTA). In this observational clinical study, 86 eyes of 86 NPDR patients with CIDME who underwent SML and PRP treatment were included. Images were obtained 1d before laser and post-laser (1d, 1wk, 1, 3, and 6mo) using AngioVue software 2.0. Best corrected visual acuity (BCVA, LogMAR), foveal avascular zone area (FAZ), choriocapillary flow area (ChF), parafoveal vessel density (PVD), capillary density inside disc (CDD), peripapillary capillary density (PCD), macular ganglion cell complex thickness (mGCCT), central macular thickness (CMT), and subfoveal choroidal thickness (ChT) were compared between pre- and post-laser treatment. BCVA remained stable during 6mo post-laser therapy (pre-laser 6mo post-laser: 0.53±0.21 0.5±0.15, >0.05). PVD, ChF, ChT, CMT, and mGCCT significantly increased 1d post-laser therapy [pre-laser 1d post-laser: superficial PVD (%), 40.51±3.42 42.43±4.68; deep PVD (%), 42.66±3.67 44.78±4.52; ChF, 1.72±0.21 1.9±0.12 mm ; ChT, 302.45±69.74 319.38±70.93 µm; CMT, 301.65±110.78 320.86±105.62 µm; mGCCT, 105.71±10.72 115.46±9.64 µm;