Effect of Panretinal Photocoagulation on Macular and Disc Vasculature using Optical Coherence Tomography Angiography

Background: To evaluate the changes of macular vascular density in the superficial capillary (SCP) and the deep capillary plexus (DCP), Foveal avascular area (FAZ), choroidal flow, macular thickness and parapapillary flow after panretinal photocoagulation (PRP).Method: In this prospective interventional non-comparative case series, patients with very severe nonproliferative (NPDR) and early proliferative diabetic retinopathy (PDR) and no significant macular edema who were candidates for panretinal photocoagulation underwent measurement of corrected distance visual acuity (CDVA), optical coherence tomography (OCT), Optical coherence tomography angiography (OCTA) at the baseline (1–5 days before PRP), 1, and 5 to 7 months following completion of PRP treatment.Results: Thirty-nine eyes from 21 patients with diabetes were enrolled. foveal SCP (P > 0.1), foveal DCP (P > 0.1), parafoveal SCP (P > 0.1), and parafoveal DCP (P > 0.1) did not change 1 month and 6 months after PRP. The parafoveal inner retina thick slab density was significantly decreased at 6 months after PRP (p=0.015). Deep FAZ area constricted 6 months following PRP (P = 0.075). Based on calculated circularity index, the FAZ area became significantly more circular. (P=0.047). One month after PRP the inside disc vascular density was significantly increased from baseline (p=0.041); while, it was decreased to lower than baseline amount, 6 months after PRP .Conclusion: Although OCTA parameters were not significantly affected by PRP at both short- (1-month) long-term (6-month) follow-up, but FAZ area may be become more circular and regular after PRP may be due to reflow of occluded capillary plexus.