Physicians must establish 48-hour intraocular pressure (IOP) profiles for patients with glaucoma to understand individual IOP fluctuations, according to findings  published in BMC Ophthalmology.

The IOP of eyes with glaucoma often fluctuates. Understanding these fluctuations — and personalizing therapies to manage them — may help manage the disease, according to researchers.

A retrospective cohort study evaluated the data of 90 glaucoma patients. All patients underwent 2 diurnal IOP profiles of 48 hours. IOP was measured at 8 AM, 2 PM, 6 PM, 9 PM using Goldmann applanation tonometry and at 12 AM using Perkins tonometry in the supine position on 2 consecutive days. 

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Each measurement of profile 1 showed moderate-to-excellent agreement (ICCs 0.62–0.93). There was a moderate-to-excellent agreement for measurements between time points of profile 1 (ICCs day 1 0.57–0.86, day 2 0.71–0.90). Profile 2 was performed at a median interval of 12.0 months (quartiles 11.0 to 21.0). Each time point agreement within profile 2 showed ICCs from 0.23 to 0.81. It showed moderate to excellent agreement for changes between time points (ICCs 0.53–0.94). Day 2 demonstrated ICCs from 0.74 to 0.88. Long-term IOP repeatability (over both pressure profiles) showed moderate-to good-agreement (ICCs 0.39–0.67).

Limitations of this study include potentially elevated IOP values after waking patients to take measurements and the use of Perkins tonometry at night due to patients’ supine position. Other limitations include interobserver variability, the inclusion of 6 subtypes of glaucoma, the inclusion of patients receiving different topical therapies, potential bias, that IOP measurements were not masked, and missing IOP values.

Investigators add that this is the first study evaluating agreement of IOP spanning 48-hours and including nighttime measurement at midnight.


Zimmermann M, Giers BC, Beck A, et al. Short- and long-term agreement and reproducibility of 48-hours intraocular pressure measurements in glaucoma patients. BMC Ophthalmol. Published online June 21, 2021. doi:10.1186/s12886-021-02003-4