The Case for Adding Self-Tonometry into Care Models

BY BARBARA M. WIROSTKO, MD, FARVO

Glaucoma is a leading cause of irreversible blindness worldwide and the second leading cause of blindness in the U.S. An estimated 53 million people in the world had open-angle glaucoma (OAG) in 2020, with a prevalence of 3% in the population aged 40–80 years.1 Prevalence studies suggest that OAG will increase by 50% worldwide as the population ages, impacting 79.8 million people by 2040.

Large prospective longitudinal studies have shown that OAG causes irreversible damage to the optic nerve, leading to visual field loss and eventual blindness. They also have revealed that glaucoma is a chronic progressive disease with inherent intraocular pressure (IOP) fluctuations. In fact, a CIGTs subgroup analysis at nine years found that the larger the range of IOP fluctuation and variability at baseline, rather than the mean and or maximum IOP, the greater the likelihood of substantial visual field loss and progression.2 Reducing IOP is the target of medical and surgical standard-of-care treatments shown to slow disease progression and prevent optic nerve damage.

So why are we not measuring IOP at various times of the day and night like other chronic diseases that demonstrate variability and fluctuation?

IOP Fluctuation Patterns

Studies have shown that diurnal and nocturnal IOP rhythms fluctuate, with spikes often occurring outside office hours and often in the early waking hours.3 In studies of IOP measured around the clock in hundreds of patients, peak IOP can occur during morning or night.4-5 In addition to elevations of more than normal IOP, wide fluctuations of IOP ranges have also been shown to contribute to glaucoma progression.2,6-7 IOP is known to fluctuate over 24 hours and longitudinally; yet, we rely on one IOP measurement every 3-4 months in the office for management decisions.

Self-Tonometry Tools Emerge

Home self-tonometry can provide robust measures of diurnal intraocular pressure, contributing to improved patient-level clinical management of IOP.

Self-tonometry is available with the iCare Home instrument. At the Moran Eye Center, my colleagues and I have been using this instrument to better diagnose and learn what a patient’s peak IOP is and to evaluate therapy responses to medications, lasers, and surgical interventions.8 By detecting changes in IOP and responses to treatments within a short period of monitoring, we can better determine and personalize what therapies are most effective.4 Self-tonometry assists us not only in determining what maximum IOP is, but also in monitoring patients at risk for progression. This may be due to diurnal fluctuation in IOP, which may be leading to damage and occurring outside of the office. Eventually, longitudinal studies will help determine if lowering that IOP spike and flattening variability can improve outcomes and reduce progression. Current data does suggest this.

Studies found that patients with glaucoma or ocular tension using home monitoring were able to detect fluctuation and patterns in IOP peak in eyes that showed progression in glaucoma despite stable in-office IOP measurement, and we are finding the same.4, 9

A recent Glaucoma Research Foundation event conference-goer demonstrates an iCare Home device, shown below.

Discussion

In addition to in-office clinical IOPs, self-tonometry studies demonstrate a positive role in obtaining an accurate IOP assessment with data to better assist treatment decision-making.4 Studies found that a significant reduction in mean IOP after selective laser trabeculoplasty (SLT) could be detected when providing self-tonometry devices to patients after their procedure.10 The data from the six-year LiGHT study also found that SLT had slower progression as compared to topical drops.11

With the development of more sustained-release glaucoma drugs and devices (i.e., Durysta and the iDose), the use of an at-home device, like the iCare Home, can help determine when the drug effect is wearing off. I have found the iCare Home device invaluable for patients receiving the Durysta and who are not in close proximity to a clinic. These IOP monitoring devices are relatively easy to use for patients, and the data is available in the cloud for physician and patient review. Plus, I have found that self-tonometry empowers the patient to understand their disease better.

As we move toward more remote patient monitoring and a digital and virtual telemedicine healthcare delivery system, I believe that home IOP monitoring will become more integral for improved glaucoma care and better personalized patient care. It will teach us not only about the individual patient’s disease course but also about glaucoma in general.

Dr. Wirostko treats glaucoma patients and specializes in clinical research. As a serial entrepreneur, she has large and small pharmaceutical company expertise and focuses on drug development for glaucoma pharmaceutical therapies. She recently co-founded MyEYES.net with a glaucoma patient to help patients access the iCare Home tonometer.

REFERENCES

1. AAO Primary Open-Angle Glaucoma Preferred Practice Pattern 2020, p. 76.

2. Musch DC, Gillespie BW, Lichter PR, Niziol LM, Janz NK. Visual field progression in the Collaborative Initial Glaucoma Treatment Study: the impact of treatment and other baseline factors. Ophthalmology. 2009;116(2):200-207.

3 . McGlumphy EJ, Mihailovic A, Ramulu PY, Johnson TV. Home Self-tonometry Trials Compared with Clinic Tonometry in Patients with Glaucoma. Ophthalmology Glaucoma. 2021 Nov-Dec;4(6):569-580.

4 . Levin AM, Vezina D, Wirostko BM. Home-Based Intraocular Pressure Measurements: Tracing a Parallel with Out-of-Office Blood Pressure Measurement. Ophthalmology Glaucoma. 2021 May-Jun;4(3):235-237.

5 . Tan S, Baig N, Hansapinyo L, et al. Comparison of self- measured diurnal intraocular pressure profiles using rebound tonometry between primary angle closure glaucoma and primary open angle glaucoma patients. PloS One. 2017;12(3): e0173905.

6. Hasegawa K, Ishida K, Sawada A, et al. Diurnal variation of intraocular pressure in suspected normaltension glaucoma. Jpn J Ophthalmology. 2006;50(5):449e454.

7. Gao F, Miller JP, Miglior S, et al. A joint model for prognostic effect of biomarker variability on outcomes: long-term intra- ocular pressure (IOP) fluctuation on the risk of developing primary open-angle glaucoma (POAG). JP J Biostat. 2011;5(2):73e96.

8. Levin AM, McGlumphy EJ, Chaya CJ, et al. The utility of home tonometry for peri-interventional decision-making in glaucoma surgery: Case series. American Journal of Ophthalmology Case Reports. 2022. https://doi.org/10.1016/j.ajoc.2022.101689.

9. Cvenkel B, Velkovska MA, Jordanova VD. Self-measurement with Icare HOME tonometer, patients’ feasibility and acceptability. Eur J Ophthalmology. 2020 Mar;30(2):258-263.

10. Awadalla MS, Qassim A, Hassall M, et al. Using Icare HOME tonometry for follow-up of patients with open-angle glaucoma before and after selective laser trabeculoplasty. JE.Clin Exp Ophthalmology. 2020 Apr;48(3):328-333.

11. Gazzard G, Konstantakopoulou E, Garway-Heath D, et al. LiGHT trial: 6-year results of primary selective laser trabeculoplasty versus eye drops for the treatment of glaucoma and ocular hypertension. Ophthalmology. 2022 Sep 16;S0161-6420(22)00732-1.

FINANCIAL DISCLOSURE

Dr. Wirostko is co-founder and medical advisor to MyEYES but receives no financial compensation for her work.