Objective:

To assess whether the water-drinking test (WDT) predicts functional and structural glaucoma progression beyond routine office intraocular pressure (IOP) measurements.

Approach:

• Study design: Prospective study of 67 eyes from 36 participants with glaucoma, followed for an average of 2.2 years and about 14 testing visits per eye.
• Stress test and outcomes: Participants drank one liter of water within five minutes. IOP was measured before drinking and at 15, 30, and 45 minutes; visual field mean deviation and retinal nerve fiber layer thickness were tracked over time.

Key Findings:

• Mean office IOP was 14.8 mmHg, while mean WDT peak IOP was 20.6 mmHg.
• Eyes with WDT peaks above 21 mmHg had faster visual field mean deviation loss and retinal nerve fiber layer thinning than eyes at or below that threshold.
• Of 59 eyes with office IOP within severity-specific targets, 22 (37%) exceeded 21 mmHg during WDT and subsequently showed faster progression than apparently controlled eyes below the threshold.
• Among 13 rapid progressors, 3 were above target by routine office measurements, whereas 10 had WDT peaks above 21 mmHg.

Interpretation:

The authors propose that WDT may act as a composite stress test of the eye’s ability to maintain IOP homeostasis, revealing pressure responses not apparent from resting office measurements.

Limitations:

• The cohort was modest in size.
• Average follow-up was just over two years.
• Treatment changes were not controlled.
• The findings require confirmation in larger, multicenter populations.

Conclusion:

The study suggests that WDT peak IOP may identify progression risk in some eyes whose office IOP appears controlled; the findings are exploratory.

Sources:

• Article context provided