Circadian Intraocular Pressure Profiles in Chronic Open Angle Glaucomas

Purpose: To evaluate circadian intraocular pressure (IOP) profiles in eyes with different types of chronic open-angle glaucoma (COAG) and normal eyes. Methods: This study included 3,561 circadian IOP profiles obtained from 1,408 eyes of 720 Caucasian individuals including glaucoma patients under topical treatment (1,072 eyes) and normal subjects (336 eyes). IOP profiles were obtained by Goldmann applanation tonometry and included measurements at 7 am, noon, 5 pm, 9 pm, and midnight. Results: Fluctuations of circadian IOP in the secondary open-angle glaucoma (SOAG) group (6.96±3.69 mmHg) was significantly (P<0.001) higher than that of the normal pressure glaucoma group (4.89±1.99 mmHg) and normal eyes (4.69±1.95 mmHg); but the difference between the two latter groups was not significant (P=0.47). Expressed as percentages, IOP fluctuations did not vary significantly among any of the study groups. Inter-ocular IOP difference for any measurement was significantly (P<0.001) smaller than the profile fluctuations. In all study groups except the SOAG group, IOP was highest at 7 am, followed by noon, 5 pm, and finally 9 pm or midnight. In the SOAG group, mean IOP measurements did not vary significantly during day and night. Conclusions: In contrast to normal eyes and eyes with primary open-angle glaucoma under topical antiglaucoma treatment, eyes with SOAG under topical treatment do not show the usual circadian IOP profile in which the highest IOP values occur in the morning, and the lowest in the evening or at midnight. These findings may have implications for timing of tonometry. Fluctuation of circadian IOP was highest in SOAG compared to other types of open angle glaucomas.