BACKGROUND The aim of this study was to assess selected retinal parameters and choroidal thickness in patients with obstructive sleep apnea. MATERIAL AND METHODS Forty-nine patients (98 eyes) were included in this prospective cross-sectional study: 33 patients with moderate or severe OSA (66 eyes) and 16 controls with no or mild OSA (32 eyes). Control and study group participants were classified according to polysomnography results. Foveal avascular zone parameters, vessel density of the superficial (SVD) and deep (DVD) capillary plexuses in the macular region, and choroidal thickness were assessed using the AngioVue Imaging System (Optovue). Results were compared between the study and control groups. Correlations between age and these measurements were calculated. RESULTS There were no significant differences in SVD or DVD between the groups (all P>0.05). Foveal avascular zone area and perimeter were significantly larger in the OSA group than in controls (P=0.0163 and P=0.0236, respectively). No significant differences were observed in foveal vessel density within 300 µm (FD-300) values (P=0.2852). Choroidal thickness measurements were significantly higher in the OSA group overall (P=0.0054), although these values showed a moderate negative correlation with age (r=-0.36, P=0.0002). CONCLUSIONS Subtle retinal microvascular alterations and increased choroidal thickness in OSA may indicate an impact of intermittent hypoxia on ocular structures. The relatively small study sample represents a limitation of the study.