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Updated: May 22, 2026
Trabecular Meshwork Response to Pressure Elevation in the Living Human Eye
Published on: June 20, 2015
Remote Tonometry Identifies Significant Variability in the Timing of Intraocular Pressure Response to Topical
Jasdeep Sabharwal1, Margaret Tharp2, Natalie Hamilton3
1Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland; North Bay Eye Associates, Petaluma, California.
Purpose:
To characterize the time to maximum intraocular pressure (IOP) change after stopping and restarting topical prostaglandin analog (PGA) treatment using remote tonometry.
Design:
A prospective single-site observational study.
Subjects:
Patients with primary open-angle glaucoma or ocular hypertension treated with ≥4 weeks of PGA monotherapy, in whom the managing ophthalmologist ordered medication washout to assess the necessity of continued topical therapy.
Methods:
Patients used a rebound home tonometer to obtain ≥4 daily measurements across 3 periods: "Baseline" (1 week while continuing PGA), "Washout" (4 weeks off therapy), and "Restart" (4 weeks while restarting PGA). Exponential decay functions were used to model IOP from "Baseline" through "Washout" and then from end of "Washout" through "Restart" to determine the time to 90% of maximum IOP change (plateau, T90%%). We evaluated the variation in T90% using multilevel models to account for the inclusion of both eyes from individual subjects.
Main Outcome Measures:
T90% for "Washout" and "Restart."
Results:
Twenty subjects (34 eyes) successfully recorded multiple daily eye measurements for the 9-week study period. Mean (standard deviation) IOPs during the "Baseline," "Washout," and "Restart" periods were 15.6 (4.2) mmHg, 17.3 (5.0) mmHg, and 15.9 (4.7) mmHg, respectively. "Baseline" and "Restart" IOPs were significantly lower than "Washout" IOP (P < 0.001). T90% was significantly longer and more variable among subjects during Washout (median: 18.5 days; interquartile range 6.0-32.1 days) compared to Restart (2.2 days; 1.3-4.1 days, P < 0.001).
Conclusions:
Using remote tonometry, we identified a significantly longer T90% after stopping PGA drops than when they were restarted. The ranges of time to reach the IOP plateau were wide, often exceeding the standardized 4-week washout, and are relevant to clinical assessment of routine treatment effects and determination of accurate washout periods for clinical research studies.
Financial Disclosure(S):
Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.
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