PURPOSE: This study aimed to evaluate the long‑term effect of panretinal photocoagulation (PRP) on the retinal nerve fiber layer (RNFL) in patients with proliferative diabetic retinopathy (PDR). METHODS: This was a prospective longitudinal cohort study examining 42 eyes of 42 patients with PDR undergoing PRP. Peripapillary RNFL thickness (RNFLT) was measured using spectral‑domain optical coherence tomography at baseline, 1 year, and 3 years following PRP. RESULTS: The mean “average RNFLT” was 89.88 ± 14.26 μm at baseline, 85.75 ± 11.36 μm at 1‑year follow‑up, and 83.33 ± 11.96 μm at 3‑year follow‑up. There was a statistically significant difference in the average RNFL thickness at baseline and 1 year and 3 years after PRP. At 1‑year follow‑up, superior, inferior, and nasal RNFL measurements reduced significantly from baseline (P < 0.01). The reduction in RNFL remained statistically significant for superior and inferior quadrants 3 years after PRP. CONCLUSION: PRP causes a reduction in RNFL thickness until 3 years after the procedure. Caution should be exercised while interpreting peripapillary RNFL thickness scans in patients who have undergone PRP for diabetic retinopathy.

PURPOSE: This study aimed to evaluate the long‑term effect of panretinal photocoagulation (PRP) on the retinal nerve fiber layer (RNFL) in patients with proliferative diabetic retinopathy (PDR). METHODS: This was a prospective longitudinal cohort study examining 42 eyes of 42 patients with PDR un...