Primary Angle-Closure Glaucoma Has Highest Intraocular Pressure Fluctuation

Primary angle-closure glaucoma fluctuates significantly throughout the day, ergo a single normal IOP value does not exclude the disease's presence.

Eyes with glaucomatous primary angle-closure disease (PACD), compared with nonglaucomatous subtypes of PACD, have the greatest fluctuations in intraocular pressure (IOP) in a 24-hour period, according to research published in the Journal of Glaucoma. Unlike prior research, this study assessed the 24-hour IOP patterns of patients who had any subtype of chronic PACD and who were naïve to treatment.

The prospective cohort study included 59 eyes (19 primary angle-closure suspect [PACS]; 23 primary angle closure [PAC]; 17 primary angle-closure glaucoma [PACG]) of 35 Asian patients aged at least 40 years from an outpatient clinic in Thailand. 

Patients underwent a complete ophthalmic examination, which included a glaucoma specialist’s performance of gonioscopy to detect peripheral anterior synechiae (PAS).

Researchers recorded IOP every 2 hours for 24 hours. Measurements were performed after topical corneal anesthesia and, at night, 10 minutes after the patient moved from supine to upright position.

The wide range of IOP fluctuation in PAC eyes may lead to the misclassification of PACD in each eye.

In univariate analysis, trough IOP did not exceed 21 mm Hg in any group.

In multivariate analysis, the primary angle-closure glaucoma group’s peak IOP, mean IOP and 24-hour intraocular pressure fluctuation were higher than those of the PACS group. The PAC group had greater peak, trough, and 24-hour IOP fluctuation compared with the PACS group. The PACG group had greater 24-hour IOP fluctuation compared with the PAC group. When the other 2 groups were combined, the PACG group had higher IOP 24-hour IOP fluctuation. The extent of PAS was linked with peak, mean and 24-hour IOP fluctuation.

The PACG group had stable mean IOP during office hours of 8 am to 4 pm, but it increased slightly during the 6 pm to 6 am period. The PAC group’s mean IOP was highest during office hours. The primary angle-closure suspect group’s highest mean IOP was from 10 am to noon and 2 am to 4 am.

“In the present study, the trough IOP values of PAC and PACG eyes without any treatment were generally in the normal range,” according to the study authors. “The wide range of IOP fluctuation in PAC eyes may lead to the misclassification of PACD in each eye. In PAC eyes without PAS, assessment based on a single normal IOP value might lead to misdiagnosis with PACS; such eyes may not receive appropriate treatment.”

Study limitations include lack of control group and influence of the possible disruption of patients’ sleep patterns on 24-hour IOP patterns.


Supakontanasan W, Suwan Y, Nilphatanakorn S, et al. Twenty-four-hour intraocular pressure in chronic primary angle-closure disease. J Glaucoma. Published online August 1, 2023. doi:10.1097/IJG.0000000000002280