To investigate the repeatability of 24-hour intraocular pressure (IOP) patterns in glaucomatous patients.

The author reviewed bilateral IOP data of 18 glaucoma patients who were admitted for 2 days. IOP data were collected in both eyes every 2 hours using Goldmann applanation tonometry during a 48-hour admission except at 02:00 o'clock (13 patients) and 04:00 o'clock (5 patients). The intraclass correlation coefficient was used to analyze the agreement of IOP patterns between the first and the second 24 hours.

IOP reached its peak between 04:00 o'clock and 06:00 o'clock in both eyes and on both days. On evaluation, the IOP data excluding the results of 02:00 o'clock and 04:00 o'clock, agreement of IOP values of 18 patients was good to excellent at 06:00, 18:00, 20:00, and 24:00 o'clock in both eyes. Agreement of IOP values at 08:00 and 12:00 o'clock was good in the right eye and the left eye, respectively. The agreement of IOP values of 13 patients who underwent IOP assessment at 04:00 o'clock and not at 02:00 o'clock, was good to excellent only at 04:00 and 06:00 o'clock in both eyes. Otherwise, agreement was poor or not significant except at 18:00 and 22:00 o'clock which showed good agreement in the right eye and the left eye, respectively.

Presumable, a circadian IOP pattern exists, because in the present study, IOP reached its peak in the early morning on both days. However, to stipulate IOP patterns were repeatable appears to be difficult since there were numerous time points with poor agreement.