Glaucoma Bonus Issue
February 2025
by Liz Hillman
Editorial Co-Director
Glaucoma specialists have now had the opportunity to come into the 21st century alongside some of the physicians in other medical specialties who have long used home monitoring devices to collect information on their patients’ conditions to better inform treatment.
For endocrinologists, it was home glucose monitoring, and for cardiologists, home blood pressure cuffs and Holter monitors. For the glaucoma specialist, the tech that is influencing both individual patient care and curating data for a growing body of research is home tonometry.
“The most important thing we do as glaucoma specialists is control the intraocular pressure because at the end of the day, that is the only modifiable risk factor for the disease. One of the key pieces of information to know whether the patient is being adequately treated or not is their intraocular pressure,” said Thomas Johnson III, MD, PhD. “Standard of care right now is to measure their intraocular pressure in the office when they come in for visits, and generally, we know that varies from minute to minute, hour to hour, day to day. When we are seeing patients in clinic, we are getting a snapshot of what their pressure is at that point in time, but it’s likely to be different at different points of the day and on different days.”
Information from home tonometry, said Barbara Wirostko, MD, has allowed ophthalmologists to go from reactionary to being proactive.
“The key here is up until now, and I think this is a pivotal concept, we have been reactionary. If we have a patient, even if they had pressures in the normal range and or teens, a lot of times we wait until we see damage,” she said. “I think what these monitoring systems allow us to do … is if we know the pressure is fluctuating, … it now allows us to be proactive and preventative.”
Source: Thomas Johnson III, MD, PhD
Applications in the clinic
Dr. Wirostko said she thinks all glaucoma patients (and glaucoma suspects or those with a significant family history) would benefit from the data collected during a week or two of home monitoring. She provided the example of a patient with exfoliation in one eye who had a suspicious nerve, a little bit of a tilt, a little thinning on their OCT, and myopia.
“One eye did not have evidence of exfoliation yet, and that eye is in the teens. The other eye runs about 2 mm more every time she’s in the clinic, so she’s 16–18, 17–19,” Dr. Wirostko said. “We always question whether to treat or not. We used iCare HOME2 [iCare], and the eye with exfoliation was spiking into the low 30s first thing in the morning. We decided to do an SLT and that completely brought the spike down; now the IOP curves are the same in both eyes, and we’ve eliminated that spike and hopefully slowed down, or at least postponed, development of damage by detecting and treating that spike ahead of damage. This could be vision saving. Otherwise, I was waiting for damage to occur on her OCT or visual field before I was going to treat her because her pressure was always within ‘normal’ in the office.”
Dr. Wirostko said the availability of home monitoring has not only been beneficial to patient care and research, but it’s been empowering for the patient as well and even has showcased the importance of drop compliance.
Dr. Thomas Johnson said the first patients he used iCare HOME2 on were those who seemed to be controlled in clinic but whose visual fields showed progression. Over time, Dr. Thomas Johnson said he learned, using the device, there are also patients who get worse at low pressures due to occult eye pressure fluctuations.
Identifying pressure fluctuations can help delay more invasive interventions. For example, if the patient already has low pressures but is progressing, a trabeculectomy might seem like the only option. But if we know, thanks to home tonometry, that patient is 13 mm Hg during the day but is spiking to 25 mm Hg early in the morning, there are several things we can do instead of a trab, Dr. Thomas Johnson said.
“We need to blunt that spike. Consider drops early in the morning, consider MIGS, consider SLT,” he said. After any of these procedures, home tonometry can confirm whether the procedure blunted the spike. “We have had a fair number of patients where we have … avoided more aggressive treatment.”
Dr. Thomas Johnson said home tonometry can also provide an extra safety element after routine surgery.
“In patients who had cataract surgery or cataract with MIGS who develop pressure spikes that are asymptomatic to them, the pressure may be going up to the high 30s or 40s and these can only be known because they were using a home tonometer. We call them in and adjust their medication and deal with it. For patients where the surgeon is concerned about pressure spikes, I think [home tonometry] can give reassurance that pressures are controlled during the postop period; [it] provides an extra safety net,” he said.
Rachel Simpson, MD, said while home tonometry is not something she does for all of her patients, she prescribes it for those whose visual fields are getting worse, despite being at goal pressures while in the clinic. She said she’s found about half of these patients are spiking outside the clinic, sometimes with IOPs that she called “shockingly high.” “It might be at 10 mm Hg when they come into clinic, 40 mm Hg at 5:00 a.m., 15 mm Hg at 8:00 a.m., and by the time they’re in the clinic to see me, back to 10 mm Hg,” she said, adding that about 50% have spikes above 8–10 mm Hg compared to their clinic IOPs.
Even if a patient isn’t spiking, Dr. Simpson said home tonometry is helpful because she knows she legitimately needs to get their pressure lower with a more invasive procedure.
Applications in research
Dr. Thomas Johnson said home tonometry has been beneficial in his clinic, but there are several research applications as well.
He is researching what the most useful home tonometry scenarios are for clinicians, something that’s important if it’s not cost effective for all glaucoma patients. He said they’re working with uveitis patients who are put on steroids to see if home tonometry can help them understand the risk of pressure spikes and the potential for sustained pressure elevations. Dr. Thomas Johnson said that research is also being conducted to see how well MIGS and SLT reduce pressure fluctuations.
Catherine Johnson, MD, MPH, who was a glaucoma research fellow with Dr. Wirostko, helped conduct a study that looked at the effect of SLT on short-term pressure spikes. The study had patients take their pressures throughout the day (beginning at 6:00 a.m.) 7 days prior to SLT and then for 7 days at 6 weeks, 3 months, and 6 months postop. Dr. Catherine Johnson said they saw a statistically significant difference in all the metrics they were looking at. There was a decrease in IOP spikes postop; maximum IOP was reduced by 3 mm Hg at 6 weeks and 4.3 mm Hg at 6 months secondary to the SLT.
“I think this study was a great jumping off point for the future research we can do, not only SLT but the different MIGS procedures,” Dr. Catherine Johnson said.
Dr. Wirostko said the Moran Eye Center, in partnership with the Wilmer Eye Institute, is also evaluating the impact of severity of a pressure spike on damage.
“We don’t know if it’s worse if you go from 10–20 mm Hg than from 20–26 mm Hg? Every patient is different, even between eyes there is a difference,” she said.
Source: iCare CLINIC
Perspectives on implantable IOP monitoring
While iCare HOME2 is the only home tonometry system that’s FDA cleared, there are some wearable or implantable monitors that are approved or in development.
One of these is the Triggerfish contact lens (Sensimed), which is FDA approved. Dr. Wirostko said this is a great innovation in concept, but she noted that it only collects 24 hours worth of data with a contact lens, and she thinks physicians need more than that to impact care.
Implantable IOP sensors, such as Eyemate (Implandata Ophthalmic Products), are an interesting concept as well, though Dr. Wirostko questioned who will be the best candidates for the implant given it is implanted at the time of glaucoma surgery.
“We know that a pressure of 25 at the cornea has an impact at the optic nerve. We know that translates to a certain amount of damage over time. … What we don’t know is if a device in the vitreous is reading 25, is that the same 25 mm Hg as the cornea? Does that 25 have the same amount of damage at the optic nerve as a 25 measured at the cornea? No one has done those studies.”
The field as a whole, Dr. Wirostko said, is very excited about the concept of continuous monitoring, but she thinks the safety/risk benefit profile needs to play out.
“The dream is continuous, accurate IOP monitoring that is patient independent,” Dr. Simpson said. “The reliability of iCare HOME2 data is good, but it’s still dependent on human operator. … There are still gaps.”
Dr. Simpson said the ideal would be an implantable device that constantly senses IOP, giving you a full 24-hour picture of what’s happening over time day after day, week after week. While the technology isn’t quite there yet, Dr. Simpson doesn’t think it’s too far away.
Article Sidebar
MyEyes
When iCare HOME2 became FDA approved, Dr. Wirostko said she tried to get it at the Moran Eye Center, but there was no reimbursement pathway for it. Instead, she and a patient cofounded MyEyes as a durable medical equipment (DME) provider for the home tonometry system, allowing patients to rent the device for a set period of time as prescribed by their doctor.
“The doctors go onto our website, load the patient’s information, our patient ambassadors contact the patient, get the device to the patient, onboard them, educate them, and it becomes a community,” Dr. Wirostko said. “We tell the patient to take several measurements during the day, especially early in the morning. Generally, a week seems to be sufficient, but we’re learning as well. They ship the device back to us, and we send the information to the doctor and the patient.”
In addition to making acquiring the device and the data more streamlined for patients and physicians, Dr. Wirostko said they’ve received feedback from physicians that the time saved in training the patient on the device, since that is taken care of by MyEyes ambassadors, is beneficial.
While there is still not a direct reimbursement pathway for iCare HOME2, Dr. Wirostko said MyEyes, as a licensed durable medical equipment provider, has helped patients submit claims to their insurance companies and seen reimbursement come back to the patient
“There is a path forward. We’re working on it, working with CPT, DME, and various consultants to help us figure out what codes are appropriate not only for the clinicians to review the data but also to get the device reimbursed and for educators to get their time as a healthcare extender covered,” she said.
About the physicians
Catherine Johnson, MD, MPH
PGY-1 Resident
Department of Ophthalmology
University at Buffalo
Buffalo, New York
Thomas Johnson III, MD, PhD
Associate Professor of Ophthalmology
Wilmer Eye Institute
Johns Hopkins University
Baltimore, Maryland
Rachel Simpson, MD
Vice Chair of Education
John A. Moran Eye Center
University of Utah
Salt Lake City, Utah
Barbara Wirostko, MD
Adjunct Professor
John A. Moran Eye Center
University of Utah
Salt Lake City, Utah
Relevant disclosures
Catherine Johnson: MyEyes
Thomas Johnson: Alcon, iCare
Simpson: AbbVie, Alcon, Glaukos, Nova Eye Medical
Wirostko: iCare, MyEyes, Qlaris
Contact
Catherine Johnson: Catherine.J.Johnson@utah.edu
Thomas Johnson: johnson@jhmi.edu
Simpson: Rachel.Simpson@hsc.utah.edu
Wirostko: barbara.wirostko@hsc.utah.edu
