Purpose To study the risk
associated with diurnal IOP variations in open angle glaucoma patients. Methods. 64 patients (105 eyes)
with open angle glaucoma performed home tonometry with office IOP below 25mmHg
over a mean follow-up period of 4 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. Results
Although mean home IOP and baseline office IOP were similar (16.4 3.6 and 17.6 3.2mmHg, respectively), the average diurnal range was 10.0 2.9mmHg. 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)). 88% of
patients in the upper 25 percentile of IOP fluctuation, and 57% of patients in
the lower 25th percentile of fluctuation, progressed within 8 years.
Conclusions In glaucoma patients with office IOP in the normal range,
large fluctuations in diurnal IOP are a significant risk factor, independent of
parameters obtained in the office.