AIM: To analyze changes of the optic nerve head (ONH) and peripapillary region during intraocular pressure (IOP) elevation in patients using spectral domain optical coherence tomography (SD-OCT).METHODS: Both an optic disc 200×200 cube scan and a high-definition 5-line raster scan were obtained from open angle glaucoma patients presented with monocular elevation of IOP (≥30 mm Hg) using SD-OCT. Additional baseline characteristics included age, gender, diagnosis, best-corrected visual acuity, refractive error, findings of slit lamp biomicroscopy, findings of dilated stereoscopic examination of the ONH and fundus, IOP, pachymetry findings, and the results of visual field.RESULTS: The 24 patients were selected and divided into two groups:group 1 patients had no history of IOP elevation or glaucoma (n=14), and group 2 patients did have history of IOP elevation or glaucoma (n=10). In each patient, the study eye with elevated IOP was classified into group H (high), and the fellow eye was classified into group L (low). The mean deviation (MD) differed significantly between groups H and L when all eyes were considered (P=0.047) and in group 2 (P=0.042), not in group 1 (P=0.893). Retinal nerve fiber layer (RNFL) average thickness (P=0.050), rim area (P=0.015), vertical cup/disc ratio (P=0.011), cup volume (P=0.028), inferior quadrant RNFL thickness (P=0.017), and clock-hour (1, 5, and 6) RNFL thicknesses (P=0.050, 0.012, and 0.018, respectively), cup depth (P=0.008), central prelaminar layer thickness (P=0.023), mid-inferior prelaminar layer thickness (P=0.023), and nasal retinal slope (P=0.034) were significantly different between the eyes with groups H and L.CONCLUSION:RNFL average thickness, rim area, vertical cup/disc ratio, cup volume, inferior quadrant RNFL thickness, and clock-hour (1, 5, and 6) RNFL thicknesses significantly changed during acute IOP elevation.