Large diurnal lOP fluctuations in glaucoma patients independently predict visual field progression

Purpose. To study the risk associated with diurnal IOP variations in open angle glaucoma patients while correcting for the first time for factors related to progression of glaucomatous damage. Methods. Patients with open angle glaucoma who successfully performed home tonometry for 5 days (5x/d) with a self-tonometer were selected if: 1) they were followedup for >l year, b) the office IOP was <25 mmHg from 1 year prior to home tonometry to the end of follow up and c) the difference between maximum and minimum office IOP was < 8 mmHg during that period. 64 patients (105 eyes)were followed-up for an average of 48 months. The presence and time of progression were identified from the clinical charts of two glaucoma experts. Parameters were defined to characterize the level and variability of the diurnal IOP obtained at home. Risk of progression was analyzed using methods for correlated outcomes. Results. Although the mean home IOP and the office IOP were 16.4 and 17.6 mmHg, respectively, the average diurnal range was 10.0 ±2.9 mmHg. The office IOP had no predictive value (relative hazard: 0.8). Diurnal IOP range and multi-day IOP range were significant risk factors for progression (relative hazard: 5.0 & 4.1) even after adjusting for office IOP, age, race, gender and visual field damage at baseline. Among the patients in the lower 25th percentile of IOP range, 43% did not progress after 8 years, compared with 12% of those in (he upper 25th percentile. African Americans progressed faster and were all in the upper 25'h percentile for IOP range. Conclusions. The results indicate that in glaucoma patients with office IOP in the normal range, large fluctuations in diurnal IOP are a significant risk factor for progression independent of data obtained in the office. Attention must be paid to IOP fluctuations in managing well-controlled glaucoma patients and to identification of treatments capable of controlling these fluctuations.