Purpose:
To study the risk associated with diurnal intraocular pressure (IOP) variations in patients with open-angle glaucoma.
Patients and Methods:
Sixty-four patients (105 eyes) from the practices of two glaucoma specialists successfully performed home tonometry with a self-tonometer five times a day for 5 days. All patients had open-angle glaucoma and documented IOP below 25 mm Hg over a mean follow-up period of 5 years. Baseline status and time to progression of visual field loss were identified from the clinical charts. The level and variability of diurnal IOP obtained using home tonometry were characterized. Risk of progression was analyzed using a nonparametric time-to-event model, incorporating methods for correlated outcomes.
Results:
Although mean home IOP and baseline office IOP were similar (16.4 ± 3.6 mm Hg and 17.6 ± 3.2 mm Hg, respectively), the average IOP range over the 5 days of home tonometry was 10.0 ± 2.9 mm Hg. Baseline office IOP had no predictive value (relative hazard, 0.98). The diurnal IOP range and the IOP range over multiple days were significant risk factors for progression, even after adjusting for office IOP, age, race, gender, and visual field damage at baseline (relative hazards [95% confidence intervals], 5.69 [1.86, 17.35] and 5.76 [2.21, 14.98]). Eighty-eight percent of patients in the upper twenty-fifth percentile of IOP and 57% of patients in the lower twentyfifth percentile progressed within 8 years.
Conclusions:
In patients with glaucoma with office IOP in the normal range, large fluctuations in diurnal IOP are a significant risk factor, independent of parameters obtained in the office. Fluctuations in IOP may be important in managing patients with glaucoma. Development of methods to control fluctuations in IOP may be warranted.
Manuscript received March 15, 1999; accepted October 7, 1999.
Ran Zeimer holds a patent on the technology. None of the other authors has financial interests.
Ran Zeimer is entitled to sales royalty from CDS Technology, L.L.C. (West Chicago, IL), which is developing products related to the research described in this paper. The terms of this arrangement have been reviewed and approved by the Johns Hopkins University in accordance with its conflict of interest policies.
Part of this manuscript was presented at the Association for Research in Vision and Ophthalmology (ARVO) meeting, May 11–16, 1997, Fort Lauderdale, Florida.
Supported in part by grant EY03841 and core grants EY01765 (The Wilmer Ophthalmological Institute) and EY01792 (University of Illinois at Chicago Eye Center) from the National Institutes of Health, Bethesda, Maryland.
Address correspondence to Ran Zeimer, PhD, Johns Hopkins University School of Medicine, Wilmer Ophthalmological Institute, Ophthalmic Physics Laboratory, 600 N. Wolfe Street, Wilmer/Woods Bldg. 355, Baltimore, MD 21287–9131.
© 2000 Lippincott Williams & Wilkins, Inc.
