The circadian curve of intraocular pressure : can we estimate its characteristics during office hours?

PURPOSE: To verify whether office-hour measurements in patients in different body positions can estimate the characteristics of 24-hour intraocular pressure (IOP). METHODS: The 24-hour IOP curves of 29 healthy subjects (10 young adults, 19 elderly) and 30 patients with untreated glaucoma were analyzed. Measurements were taken at 9 AM; 12, 3, 6, and 9 PM; and 12, 3, and 6 AM, both in the supine and sitting (Goldmann tonometer) positions. Peak, mean, and fluctuation of 24-hour IOP curves were compared with office-hour measurements obtained in subjects in the sitting position alone and with combined pressures obtained in the sitting and supine positions (four measurements in each body position from 9 AM to 6 PM). The percentage of subjects with estimates of all IOP parameters within a cutoff of +/-1 (peak and mean) and +/-2 mm Hg (fluctuation) was calculated. RESULTS: Office-hour sitting measurements correctly identified peak, mean, and IOP fluctuation in 10% of the young adults, 32% of the elderly control subjects, and 20% of the patients with glaucoma, whereas the combination of supine and sitting measurements correctly identified them in 30%, 85%, and 46% of cases, respectively. It is noteworthy that office-hour measurements did not characterize any 24-hour parameter in 20% of patients with glaucoma. CONCLUSIONS: Compared with sitting measurements alone, the collection of supine and sitting office-hour measurements may enhance the correct identification of 24-hour IOP characteristics in both control subjects and untreated patients with glaucoma, thus reducing the need for obtaining 24-hour curves to a minority of patients.