Macular vessel density before and after panretinal photocoagulation in patients with proliferative diabetic retinopathy

Introduction Diabetic retinopathy (DR) is microangiopathy causing ischemia leading to proliferative diabetic retinopathy and macular edema. Panretinal photocoagulation (PRP) reverses the ischemia leading to regression of neovessels. Most previous studies showed the large vessel effects of PRP, while optical coherence tomography angiography (OCTA) allowed noninvasive quantification of microvascular retinal changes. Aim To study the effect of PRP on microvascular retinal vessels in a detailed manner at different retinal and choroidal levels using OCTA. Patients and methods This study was a prospective interventional study. 30 eyes of 18 diabetic patients with PDR were included. All patients were evaluated clinically and with OCTA (Avanti RTVue-XR system, Optovue) to evaluate superficial and deep vessels density (VDs), choroidal flow, and FAZ area before PRP (base line) and 1 month and 6 months after PRP. Results PRP improved vessels density at superficial (SCP), deep (DCP), and choriocapillaris levels. Foveal vessel density at SCP and DCP were statistically significantly increased. SCP was 28.76 +/- 2.56 at base line and was increased to 29.84 +/- 2.47 and 30.89 +/- 2.20 after 1 month and after 6 months, respectively. DCP was 34.08 +/- 5.59 at base line and was increased to 34.93 +/- 5.66 and 36.09 +/- 5.62 after 1 month and after 6 months, respectively. Foveal choriocapillaris was statistically significantly increased from 63.04 +/- 2.66 at base line to 63.48 +/- 2.65 and 63.98 +/- 2.78 after 1 month and 6 months, respectively. Choroidal flow was increased from 1.74 +/- 0.07 at base line to 1.75 +/- 0.09 at 1 month which was nonsignificant (P = 0.72), but it was significantly increased to 1.87 +/- 0.27 6 months after PRP (P = 0.009). FAZ area was significantly improved after PRP. FAZ area was decreased from 0.56 +/- 0.27 at base line to 0.50 +/- 0.21 after 1 month and to 0.46 +/- 0.21 after 6 months. Conclusion OCTA parameters were significantly improved by PRP in PDR patients, possibly due to redistribution of blood in occluded capillary plexuses. Trials registry: NCT04976361.