To evaluate the effect of macular photocoagulation [MPC] on peripapillary nerve fiber layer [PNFL] thickness measurement in patients with clinically significant diabetic macular edema [CSME] . This study was a prospective interventional case series. Patients with CSME underwent MPC. Optical coherence tomography [OCT] was used to measure the PNFL and central macular thicknesses before and 3 months after MPC. Thirty-three eyes of 25 patients with a mean age of 59.4 +/- 7.2 years were included. There was no statistically significant difference between pre- and post-MPC mean best corrected visual acuity [0.35 +/- 0.29 and 0.40 +/- 0.23 LogMAR, respectively, P = 0.2] . Mean baseline and 3 months central macular subfield thickness was 305.9 +/- 90.7 and 317.5 +/- 112.4 microns, respectively [P = 0.1] . Peripapillary nerve fiber layer thickness was 105.7 +/- 10.0 before and 106.1 +/- 9.9 three months after MPC [P = 0.7] . No significant differences were found between pre and post MPC measurements in temporal, nasal, inferior and superior nerve fiber layer thickness in each quadrant around optic nerve head [P > 0.05] . Macular photocoagulation has no statistically significant effect on PNFL thickness measurements in patients with CSME