Single intraocular pressure measurements and diurnal intraocular pressure profiles

PURPOSE: To evaluate the probability of a single intraocular pressure measurement to be the highest measurement within a diurnal intraocular pressure profile. DESIGN: Hospital-based clinical, observational study. METHODS: The study included 3,025 day-and-night intraocular pressure profiles measured on 1,072 eyes of 547 Caucasian glaucoma patients or glaucoma suspects. Applanation tonometry was performed at 7 AM, noon, 5 PM, 9 PM, and midnight. RESULTS: Intraocular pressure measurements were high, est at 7 AM, noon, 5 Pm, 9 Pm, and midnight, respectively, in 20.4%, 17.8%, 21.3% 13.9%, and 26.7% of the profiles, respectively. The measurement taken at 7 AM was significantly (P < .001) closest to the maximal value of the profile. CONCLUSIONS: Any single intraocular pressure measurement taken between 7 AM and 9 PM has a higher than 75% chance to miss the highest point of a diurnal curve. Intraocular pressure may be measured at different times of the day to have the best chance of observing the maximal value. (c) 2005 by Elsevier Inc. All rights reserved.