Diurnal Intraocular Pressure Profiles in Chronic Open-Angle Glaucoma

Purpose: To evaluate day-and-night intraocular pressure (IOP) profiles in normal and glaucomatous eyes. Design: Hospital-based clinical observational study. Methods: The study included 3561 day-and-night profiles of IOP measurements performed by Goldmann applanation tonometry on 1408 eyes of 720 normal Caucasian subjects or chronic open-angle glaucoma patients. Results: For all groups except the secondary open-angle glaucoma group, IOP was highest at 7 a.m., followed by noon and 5 p.m., and finally at 9 p.m. or midnight. In secondary open-angle glaucoma, mean measurements did not vary significantly during day and night. The profile amplitude (mean: 5.5 2.8mmHg) was significantly (P < 0.001) higher in the secondary open-angle glaucoma group than in the normal-pressure glaucoma group and the normal group. The two latter groups did not vary significantly (P = 0.47) in profile amplitude. Expressed as percentage of the mean IOP, the IOP amplitude did not vary significantly between any of the study groups. The inter-eye IOP difference for any measurement time was significantly (P < 0.001) smaller than the IOP profile amplitude. Conclusions: Treated secondary open-angle glaucoma eyes did not exhibit the normal day-and-night pressure profile which was usually shown in normal eyes and eyes treated for other types of chronic openangle glaucoma. The day-and-night IOP amplitude in absolute terms is highest in secondary open-angle glaucoma. In relative terms, the IOP amplitude did not vary significantly between the various types of chronic open-angle glaucoma. Inter-eye IOP differences were significantly (P < 0.001) smaller than the IOP profile amplitude.