In this study, changes in Retinal Nerve Fiber Layer (RNFL) within peripapillar zone in patients with diabetic retinopathy that accomplish criteria to receive panretinal photocoagulation are analyzed by TD-OCT (Time Domain-Optic Coherence Tomography) unit. This analysis was transversal retrospective and observational and was done in 46 eyes from 33 patients. According to laser application technique, time since application and day of the study, 4 groups of patients were set: the first with patients with less than 30 days since last laser application and day of study. The second with patients with 180 days since laser photocoagulation; the last two groups received panretinal photocoagulation plus macular selective laser with a TD-OCT performed 30 days (for the third group) and 180 days (the fourth group) after administration of treatment. The clinically significant finding was in comparing the group that received panretinal photocoagulation with TD-OCT after 30 days, and the group that received panretinal photocoagulation and TD-OCT after 180 days. Average thickness was less in the second group, with a statistical significant finding p=0.012 in inferior quadrant. Administer laser photocoagulation makes changes in the structure and function of the retina, and according to references many different results may be possible taking in count the equipment used to apply treatment and to take measurements. The patient must be informed about secondary and adverse effects after the treatment