Purpose of review: The measurement of intraocular pressure (IOP) is essential in the diagnosis and management of open-angle glaucoma, but a single measurement in the ophthalmologist's office may or may not reflect what the IOP is at other times of the day or night. It is well documented that the range of the daily fluctuations in IOP is greater in patients with glaucoma than in normal individuals, and a report by Asrani et al. suggested that the range of the diurnal fluctuation may be an independent risk factor for the progression of visual field loss. There have been reports of nocturnal increases in IOP, particularly in patients with normal tension glaucoma, and some ophthalmologists believe these may account for progression of visual field loss in some patients with glaucoma. This review will analyze recent articles that report the impact of various glaucoma therapies on the diurnal IOP curve and the use of diurnal curves in glaucoma diagnosis.
Recent findings: A number of recent publications document that antiglaucoma medications with a long duration of action reduce the range of diurnal fluctuation more than the shorter duration medications. Laser trabeculoplasty and trabeculectomy also narrow the range of diurnal fluctuation, and at least one recent study finds that trabeculectomy reduces the diurnal range more than medical therapy does. Several recent studies of diurnal IOP in patients with glaucoma have failed to document such diurnal IOP spikes, so the published data available have not supported this hypothesis.
Summary: One recent report has reconfirmed that a single IOP measurement in the office may not accurately indicate what is happening to the IOP of a patient with glaucoma throughout the day. Other reports have confirmed that treatment that lowers IOP narrows the range of diurnal IOP fluctuation, and one of these reports suggests that surgical reduction of IOL may narrow the fluctuation more than medical reduction of IOP. The reports of IOP during the night have not provided clear answers about what happens to IOP during sleep.