The aim of this study was to investigate retinal nerve fiber layer (RNFL) thickness and macular changes (central subfield thickness, cube average thickness, cube volume) in patients with chronic migraine (CM) without visual impairment using spectral-domain optical coherence tomography (SD-OCT) and to compare the results to healthy controls. A total of 80 subjects, including 40 CM patients (18 females, 12 males, at 19-36 years of age) with no migraine prophylactic treatment and 40 healthy controls (16 females, 14 males, at 20-40 years of age) were enrolled. Both eyes of patients with CM and controls were imaged using Cirrus HD SD-OCT (Carl Zeiss Meditec, Dublin, CA, USA). The average RNFL thickness was not significantly thinner in patients with CM. The mean average RNFL thickness was 83 +/- A 10.5 mu m in CM patients and 85 +/- A 9.6 mu m in healthy controls (p = 0.648), but superior quadrant RNFL thickness in the CM patients was significantly lower than healthy controls. The mean superior RNFL thickness was 86 +/- A 6.7 mu m in CM patients and 108 +/- A 7.3 mu m in controls (p < 0.001). Illness duration and frequency of the attacks were not affected by RNFL thickness. No significant differences were detected in macular changes between CM patients and healthy controls. In our study, the thickness of superior RNFL was found to be thinner in CM patients. This implies that longitudinal follow-up is needed to clarify whether RNFL thinning, in migraine patients, is related to a progressive loss of axons and retinal ganglion cells.