The Science Behind Home Tonometry
A growing body of peer-reviewed research supports home IOP monitoring as a critical tool for glaucoma management. Here is what the evidence says.
IOP and Glaucoma: An Evolving Understanding
Intraocular pressure (IOP) is the only modifiable risk factor for glaucoma — the world's leading cause of irreversible blindness. Lowering IOP remains the primary strategy for slowing disease progression and preserving vision.
Landmark clinical trials have consistently demonstrated the value of IOP reduction. The Collaborative Initial Glaucoma Treatment Study (CIGTS) showed that aggressive IOP lowering reduced visual field loss in patients with advanced disease.[1] The Ocular Hypertension Treatment Study (OHTS) found that a 20% reduction in IOP cut the risk of developing glaucoma by more than half.[3]
However, these trials assessed IOP using isolated measurements at periodic clinic visits. A 2024 comprehensive review published in Progress in Retinal and Eye Research — co-authored by MyEyes founder Dr. Barbara Wirostko — argues that this approach provides an incomplete picture and that ambulatory IOP monitoring is positioned to improve outcomes, much as home blood pressure monitors did for hypertension.[3]
What Self-Monitoring Studies Reveal
Two key studies demonstrate that home tonometry captures pressure behavior invisible to clinic visits.
Self-Monitoring Identifies Progression Risk
Cvenkel et al. studied 94 glaucoma and ocular hypertension patients who self-monitored IOP at home over 3 days using the iCare HOME. Despite all patients having controlled IOP at office visits, home monitoring revealed significant differences between progressing and stable eyes:
Avg IOP
15.8
13.3
mmHg
Peak IOP
21.8
18.6
mmHg
Fluctuation
11.6
9.1
mmHg range
Cvenkel B, Atanasovska Velkovska M. Clinical Ophthalmology. 2019.[4]
Home Tonometry Reveals What Clinics Miss
McGlumphy et al. analyzed 107 eyes from 61 glaucoma patients at Johns Hopkins who completed one week of home self-tonometry with the iCare HOME. Home measurements were compared against the five preceding clinic visits.
50%
of days, peak IOP occurred outside office hours
44%
of patients' daily max exceeded their clinic max
31%
exceeded target IOP by 3+ mmHg at home
McGlumphy EJ, et al. Ophthalmology Glaucoma. 2021.[2]
For Clinicians: Clinical Evidence Summary
IOP Targets: CIGTS data demonstrated that aggressive IOP lowering (≥35% from baseline) significantly reduced visual field progression in patients with more advanced disease at diagnosis. Initial surgery led to less VF progression than initial medicine in these patients.[1]
Ambulatory Monitoring: Asrani et al. (2024) reviewed the complete evidence base and conclude that ambulatory IOP monitoring provides discrete data that could improve outcomes. The review highlights that IOP fluctuation is an independent risk factor for progression, beyond mean or peak IOP alone, and recommends prospective randomized controlled studies to determine whether remote tonometry-based management might reduce vision loss.[3]
Peri-Interventional Use: Levin, McGlumphy, Chaya, Wirostko, and Johnson (2022) described 12 cases in which home IOP monitoring complemented clinical decision-making around glaucoma surgery — establishing pre-treatment IOP patterns, demonstrating treatment response, and providing nyctohemeral fluctuation data not ascertainable through in-clinic tonometry.[5]
Expert and Patient Perspectives
Leading researchers and patients who use home tonometry weigh in on its value.
“At-Home Glaucoma Monitoring: Is it Ready for Prime Time?”
In a 2022 editorial in Ophthalmology Glaucoma, Turner and Ou concluded that home IOP testing is ready to provide supplementary data to improve glaucoma care and reduce clinic visits. They noted that iCare HOME has shown acceptable correlation with Goldmann applanation tonometry, is quick and comfortable, and that 90% of patients expressed interest in self-tonometry.[6]
At-Home Multi-Day Glaucoma Testing
A Stanford pilot study by Berneshawi, Shue, and Chang (2024) evaluated unsupervised, at-home, multi-day glaucoma testing combining VR visual fields and iCare HOME tonometry. At-home tonometry yielded statistically higher maximum IOP values than in-clinic measurements, further supporting the value of out-of-office monitoring.[7]
“You Feel Like You Are Part of the Treatment”
In a published roundtable in Glaucoma Today, long-time glaucoma patient Dorian De Maio described using the iCare HOME for over 1.5 years. Home monitoring data led to a surgery decision and enabled his physicians to detect when a treatment began wearing off at the 6-month mark — prompting an immediate medication adjustment without waiting for a clinic appointment.[8]
“From a patient point of view, when you go to the clinic on a periodic basis and know that your pressures may vary according to the day, you feel a bit hopeless and like you have no control. With the iCare Home, you can build a closer relationship with your provider and feel like you are part of the treatment.”
What This Means for You
- Your office IOP readings are a starting point, but they may not capture the pressure behavior most relevant to your glaucoma risk.
- Home monitoring reveals IOP spikes, fluctuations, and patterns that occur outside of clinic hours — data your doctor needs to fine-tune your treatment.
- The iCare HOME has been validated in peer-reviewed studies at institutions including Johns Hopkins, Stanford, the University of Utah, and Duke.
- Research supports that more comprehensive IOP data can lead to better-timed interventions and more personalized treatment plans.
Evidence-Based Monitoring
Whether you're a patient looking for better IOP data or a clinician exploring home monitoring for your practice, we're here to help.
References
- Musch DC, Gillespie BW, Lichter PR, Niziol LM, Janz NK; CIGTS Study Investigators. Visual field progression in the Collaborative Initial Glaucoma Treatment Study: the impact of treatment and other baseline factors. Ophthalmology. 2009;116(2):200-207. doi:10.1016/j.ophtha.2008.08.051
- McGlumphy EJ, Mihailovic A, Ramulu PY, Johnson TV. Home self-tonometry trials compared with clinic tonometry in patients with glaucoma. Ophthalmology Glaucoma. 2021;4(6):569-580. doi:10.1016/j.ogla.2021.03.017
- Asrani SG, McGlumphy EJ, Al-Aswad LA, et al. The relationship between intraocular pressure and glaucoma: an evolving concept. Prog Retin Eye Res. 2024;103:101303. doi:10.1016/j.preteyeres.2024.101303
- Cvenkel B, Atanasovska Velkovska M. Self-monitoring of intraocular pressure using Icare HOME tonometry in clinical practice. Clin Ophthalmol. 2019;13:841-847. doi:10.2147/OPTH.S198846
- Levin AM, McGlumphy EJ, Chaya CJ, Wirostko BM, Johnson TV. The utility of home tonometry for peri-interventional decision-making in glaucoma surgery: case series. Am J Ophthalmol Case Rep. 2022;28:101689. doi:10.1016/j.ajoc.2022.101689
- Turner M, Ou Y. At-home glaucoma monitoring: is it ready for prime time? [editorial]. Ophthalmology Glaucoma. 2023;6(2):117-119. doi:10.1016/j.ogla.2022.08.009
- Berneshawi AR, Shue A, Chang RT. Glaucoma home self-testing using VR visual fields and rebound tonometry versus in-clinic perimetry and Goldmann applanation tonometry: a pilot study. Transl Vis Sci Technol. 2024;13(8):7. doi:10.1167/tvst.13.8.7
- Kahn R, De Maio D, Wirostko B, Chaya C. Remote diagnostics for closer clinical teamwork [roundtable]. Glaucoma Today. March/April 2022.
- Ou Y. At-home tools for the glaucoma patient. Glaucoma Today. November 2023.