Intraocular Pressure Stress Testing Identifies Glaucoma Eyes at Risk of Fast Progression Despite Controlled Office Pressure.

PURPOSE: To evaluate whether an intraocular pressure (IOP) stress test can identify glaucoma eyes at risk for faster functional and structural progression despite apparently controlled office IOP.

DESIGN

Prospective cohort study.

PARTICIPANTS

Sixty-seven eyes of 36 participants with glaucoma.

METHODS

Participants underwent a standardized water-drinking test (WDT) as an IOP stress test. Visual field and spectral-domain optical coherence tomography testing were obtained in clusters (five visits) at baseline and end of follow-up, with interim single visits every 6 months between clusters. Rates of mean deviation (MD) change and retinal nerve fiber layer (RNFL) thinning were estimated by ordinary least-squares regression. Associations between WDT-derived IOP parameters and rates of change were assessed, including analyses stratified by severity-specific target IOP. Multivariable generalized estimating equation models evaluated WDT peak IOP and its association with progression after adjustment for office IOP and clinical covariates.

MAIN OUTCOME MEASURES: Rates of MD change and global RNFL thinning over time.

RESULTS

Mean follow-up after the WDT was 2.2 ± 1.0 years, with a mean of 14 ± 5 testing visits per eye. Among 59 eyes whose office IOP was within severity-specific target, 22 (37%) had WDT peak IOP > 21 mm Hg and showed significantly faster rate of MD loss (-0.67 vs +0.16 dB/y, P = .009) and RNFL thinning (-0.74 vs -0.18 µm/y, P = .002) than the remaining office-controlled eyes. Thirteen eyes (19%) were classified as fast progressors. Most rapidly progressing eyes would have been considered adequately controlled by office tonometry, with only 3 of 13 (23%) above target, whereas the WDT peak exceeded 21 mm Hg in 10 of 13 (77%). In multivariable models, WDT peak IOP > 21 mm Hg remained significantly associated with faster MD change (β = -0.659 dB/y, P = .006) and RNFL change (β = -0.467 µm/y, P = .035) after adjustment for office IOP, indicating complementary prognostic information; results were similar when WDT peak and office IOP were modeled continuously or symmetrically.

CONCLUSIONS

IOP stress testing was associated with faster functional and structural glaucoma progression and identified higher risk eyes among those with apparently controlled office IOP, providing risk information complementary to routine office tonometry.