Comparison between the Effects of Conventional versus Pattern Panretinal Photocoagulation (PRP) for Proliferative Diabetic Retinopathy (PDR) on Macular and Optic Nerve Head Perfusion using Optical Coherence Tomography Angiography (OCTA).

Background: Diabetic retinopathy(DR), causing ischemia, leads to proliferative diabetic retinopathy. This ischemia is reversed by Panretinal photocoagulation (PRP) leading to regression of neovessels. Optical coherence tomography angiography (OCTA) allows noninvasive quantification of retinal microvascular changes. Patients and methods: This was a prospective interventional comparative study. Conducted on 60 eyes of 60 patients with proliferative diabetic retinopathy divided into two groups: Group A: 30 eyes of 30 patients underwent conventional PRP laser. Group B: 30 eyes of 30 patients underwent pattern PRP laser. All patients were evaluated clinically and with OCTA to evaluate superficial and deep vessels density and FAZ area before PRP (base line) and 3 months after PRP. Results: FAZ slightly more reduction in the Conventional group, but that was not statistically significant (p = 0.167). Regarding Foveal Vascular Density at SCP and DCP, mixed results with some measurements favoring Conventional and others favoring Pattern intervention. Significant differences are noted in Foveal vessel density at SCP (p = 0.005), DCP (p = 0.046), and Whole Image DCP (p = 0.002) favoring the conventional group. However, Para foveal vessel density at SCP showed a significant improvement favoring the pattern group (p = 0.014). Conclusion: OCTA parameters were significantly improved by PRP in PDR patients, possibly due to redistribution of blood in occluded capillary. OCTA has several advantages ( noninvasive, requires shorter time for imaging and less affected by hemorrhage or leakage). So, we recommend that OCTA to be used in as part of the routine follow up of DR patients.