Background: Diabetic retinopathy is one of the most common causes of vision loss in developed countries. Objective: The objective of this study was to assess the effect of diabetic retinopathy (DR) on the retinal nerve fiber layer (RNFL) thickness. Patients and methods: This study was carried out on 55 eyes of 35 patients designed as a prospective, interventional case series at Sohag Hospital from January, 2016 to December, 2016. A complete ophthalmologic examination was performed including best-corrected visual acuity (BCVA) using the ETDRS charts, intraocular pressure (IOP) measurement, slit-lamp biomicroscopic examination, fundus examination and fluorescein angiography. Results: The RNFL (inferior and total) thickness at each follow-up was increased significantly from baseline to 1 month and 6 months post-PRP then decreased significantly from 1 month to 6 months follow up (p < 0.001). The superior RNFL was increased significantly from baseline to 1 month post-PRP and then decreased at 6 month follow up (p < 0.001). While no significant change from 1 month to 6 months follow up (p > 0.05). Conclusion: Increase in the macular Ganglion cell (GC) thickness and RNFL at 1 month of follow-up that may be related to laser induced intraretinal inflammation which triggers increased capillary permeability and ensuing axonal edema due to the cytokine release.