We evaluated 132 eyes of 132 consecutive patients (67 men and 65 women) with NTG (mean age ± SD, 60.4 ± 14.4 years) in a retrospective chart review. We reviewed the medical records of each patient with NTG who was seen by a glaucoma specialist (MSK) during the period from April 2000 to December 2004. All patients with diagnosed NTG based on clinical evaluation and visual field examination had undergone in-hospital 24-hour monitoring of IOP and BP, by a method described later in the article. Patients were eligible if they a had glaucomatous optic nerve appearance, including diffuse or focal neural rim thinning, hemorrhage, enlarged cupping, or nerve fiber layer defects indicative of glaucoma in addition to corresponding visual field loss, best-corrected visual acuity more than 20/40, maximum IOP less than 22 mm Hg on multiple measurements (at least three independent results) using Goldmann applanation tonometry (GAT), normal anterior chamber, and an open-angle on slit-lamp and gonioscopic examination, and glaucomatous visual field damage. Patients with evidence of intracranial or otolaryngeal lesion, history of massive hemorrhage or hemodynamic crisis, previous or current use of antiglaucoma medication, any other ophthalmic disease that could result in visual field defects, or a history of diabetes mellitus were not eligible for this study. Patients on antihypertensive or other hemodynamically active medications were not excluded. Patients with IOP greater than 21 mm Hg during in-hospital 24-hour monitoring were also excluded from the study. Central corneal thickness (CCT) was measured three times by ultrasonic pachymetry (DGH-550; DGH Technology Inc., Exton, PA) in all patients on the first visit, and the average in each patient was calculated. The affected eye was selected in patients with unilateral disease, and if both eyes of a patient showed NTG and met the inclusion criteria, one eye was randomly selected for entry. All procedures conformed to the Declaration of Helsinki, and the study was approved by the institutional review board of the Asan Medical Center at the University of Ulsan, Korea.