INTRODUCTION: Intraocular pressure (IOP) is a major risk factor for the development of open angle glaucoma (OAG). Intraocular pressure control is the main target of glaucoma therapy at the moment. The 24-hour intraocular pressure curve (circadian curve-CC) is of great importance for open angle glau-coma diagnosis and follow-up. Because of practical facilities, simplified methods such as the diurnal curve (DC) have been used. PURPOSE: Comparison between circadian curve and diurnal curve as regards intraocular pressure peak detection and the verification of the influence of postural variation on 6 a.m. measurement. METHODS: Sixty-four open angle glaucoma or suspected glaucoma patients (126 eyes) were submitted to circadian curve. Diurnal curves considered 9 a.m. - noon - 3 p.m. 6 p.m. measurements of the circadian curve. At 6 a.m., measurements were performed in the dark, while patients were lying, with the Perkins tonometer. Then, another measurement was taken, with the Goldmann tonometer with the patients seated. Mean intraocular pressure and intraocular pressure peaks in the circadian and diurnal curves were compared, as well as the time when the peaks occurred. RESULTS: Mean IOP was higher in the open angle glaucoma patients in both the circadian curve and diurnal curve. When the circadian curve and diurnal curve were compared, mean intraocular pressure was higher in the 6 a.m. circadian curve IOP measurement was higher when taken in bed. The diurnal curve did not detect 60.42% of the peaks in open angle glaucoma patients and 88.24% of the peaks in suspected glaucoma patients. CONCLUSIONS: 1. The circadian curve detects more intraocular pressure peaks than the diurnal curve; 2. Six a.m. intraocular pressure is higher when taken in bed; 3. 6 a.m. intraocular pressure in bed is higher than the mean intraocular pressure in both circadian curve and diurnal curve.
Intraocular pressure; Glaucoma open-angle; Tonometry; Circadian rhythm; Ocular hypertension; Visual fields
