Abstract
Abstract: :
Purpose: To identify the features of diurnal variation of intraocular pressure (IOP) in normal–tension glaucoma (NTG). Methods: A total of 575 patients were suspected to have NTG in Gifu University Hospital between 1989 and 2003 based on structural and functional abnormality indicating glaucoma but lacking high IOP (> 20 mmHg) and underlying pathology. Goldmann applanation tonometry was repeatedly performed for 24 hrs at 2–hr intervals without medication or after 4–week discontinuation of all medications. Results:Twenty–nine patients (5%) showed high IOP (≥ 21 mmHg) at least one eye during the IOP phasing. In the remaining 546 established NTG cases, the average, maximum and minimum IOPs were 13.9±2.0 mmHg (mean ± SD), 16.0±2.2 mmHg, and 11.7±2.1 mmHg, respectively. The diurnal variation ranged from 1 to 10 mmHg and averaged 4.3±1.6 mmHg. The peak IOP was recorded during 0800–1600 hrs in 66.6% of the cases and the trough during 2400–0400 hrs in 44.2%. In 13 patients (2.3%) out of 563 patients (97.2%) who showed all IOPs during office hours (1000–1600) within 20 mmHg, IOP was over 20 mmHg at least once outside of the office hours. Conclusions: Basic features of diurnal IOP variation in NTG have been elucidated. Approximately 5% of all patients suspected NTG showed IOP over 20 mmHg during 24–hr IOP phasing.
Keywords: clinical research methodology • circadian rhythms