Regression Patterns of Neovascularization in Proliferative Diabetic Retinopathy Following Panretinal Photocoagulation - A Prospective, Observational Study

Barkha Singh,1 Vijaya Sahu,1 Aseem Kumar,1 Shivani Shrivastava,1 Bharat Gurnani,2 Kirandeep Kaur3 1Department of Ophthalmology, All India Institute of Medical Sciences, Raipur, Chhattisgarh, 492099, India; 2Department of Cataract, Cornea and Refractive Surgery, Gomabai Netralaya and Research Centre, Neemuch, Madhya Pradesh, 458441, India; 3Department of Cataract, Pediatric Ophthalmology and Strabismus, Gomabai Netralaya and Research Centre, Neemuch, Madhya Pradesh, 458441, IndiaCorrespondence: Vijaya Sahu, Department of Ophthalmology, All India Institute of Medical Sciences, Raipur, Chhattisgarh, 492099, India, Tel +91 9752679556, Email drvijayasahu77@gmail.comPurpose: To determine the short-term patterns of regression of neovascularization after panretinal photocoagulation (PRP) in eyes with proliferative diabetic retinopathy (PDR) without clinically significant macular edema.Methods: The study was a prospective, observational pilot study conducted at a tertiary care hospital in India from January 2023 to April 2024. The single eye (worst eye) of 30 patients with PDR without diabetic macular edema was selected using convenient sampling. This approach was chosen to avoid inter-eye correlation bias. The patients meeting the inclusion criteria underwent PRP laser using Green LASER (532nm), and visual acuity (VA), central macular thickness (CMT), and fundus photographs were analyzed at baseline, 1 month, and 3 months post-PRP.Results: The VA at baseline remained similar at 1-month and 3-month post-PRP. The CMT increased significantly at 1-month and 3 months but was within 300 microns, remaining below the threshold for clinically significant macular edema. No regression was seen at one month in most eyes. However, at 3 months, complete regression was seen in 10% of cases, incomplete regression in 47%. There was no difference in the regression rates based on the amount of neovascularization at baseline. NVD showed a higher odds ratio for non-regression; however, this did not reach statistical significance, and a 25-micron increment in spot size demonstrated a non-significant trend toward reduced likelihood of non-regression. Every 1gm% HbA1c increment was associated with a 2.7 times higher likelihood of CME.Conclusion: In this pilot study, short-term regression of neovascularization following PRP was variable. Exploratory trends suggested possible differential regression between NVD and NVE.Keywords: neovascularization, panretinal photocoagulation, proliferative diabetic retinopathy, green laser, iabetes mellitus