How Remote Intraocular Pressure Monitoring Can Redefine Glaucoma Care

For the better part of 2020, patients who needed treatment for non-life-threatening medical conditions experienced obstacles to obtaining in-person care due to the COVID-19 pandemic. While telemedicine technologies addressed a number of these concerns within a safe and convenient setting, questionable online security, an inability to perform certain types of testing, and the failure of some insurance companies to cover these costs may limit both patients’ and clinicians’ ability or willingness to perform such visits.¹ Patients with glaucoma experienced barriers to care during the pandemic — a 2021 study reported a 92.52% decrease in clinical visits, a 93.84% decrease in visual field exams, and a 72.74% decrease in glaucoma procedures among these individuals.² Routine clinical visits are optimal for individuals with this sight-threatening condition, but it may present a challenge for patients with limited access to transportation, limited availability, and lingering COVID-19-related concerns. Telemetric glaucoma monitoring, while not in its infancy, may soon grow into a feasible option.  

At-Home Options

It may not be possible to perform every clinically meaningful glaucoma test within the confines of one’s home, but some technologies are now allowing patients to obtain IOP measurements without a clinician’s assistance. For one example, portable rebound devices, unlike the applanation devices used in clinics, do not require any type of anesthetic. Machine-guided lights enable the patient to properly position the device and take a measurement, removing the need for clinician assistance.³ Once the device is positioned, patients push a button, which releases a probe.³ As the probe taps the cornea and retracts, the machine measures its speed. Faster speed indicates a harder cornea, which indicates higher IOP.³  While the Goldmann applanation tonometer (GAT) remains the gold standard for IOP measurement, portable rebound devices may be sufficient for monitoring IOP in individuals who are unable to attend in-person visits.⁴    

Disabilities, poor dexterity, and other concerns may limit a patient’s ability to perform these measurements. These individuals may benefit from either an implantable device or a contact lens containing an IOP sensor, which can allow clinicians access to real-time data without the need for direct communication with the patient.⁵ A contact lens that contains an embedded electromechanical sensor can detect changes in the corneoscleral limbus resulting from IOP variations.⁶ The device records IOP for a 30-second interval every 5 minutes for a total of 86,400 points during the course of a day.^6,7 There is no need for frequent communication with an eye care professional, as these readings are transmitted directly to their computer courtesy of portable recorder worn by the patient.⁷ Some of these devices have not only demonstrated excellent biocompatibility, but limits of detection that are comparable with GAT.⁵ 

The IOP Diurnal Curve 

At times, telemedicine may offer benefits that clinical visits cannot provide. Despite applanation tonometry’s ability to provide accurate IOP measurements during in-person visits, it fails to provide around-the-clock readings for patients who may need consistent monitoring, Jeff M. Miller, OD, professor of optometry at Northeastern State University Oklahoma School of Optometry argued. 

“The more data points, the better with glaucoma,” Dr Miller said. “As doctors, we only get snapshot information: we know the patient’s IOP at a precise moment in our office, but what is it doing early in the morning? Overnight? A better idea of the IOP diurnal curve can help us better assess the need for treatment and the efficacy of treatment.” 

Elyse McGlumphy, MD, assistant professor of ophthalmology at Wilmer Eye Institute, expressed similar thoughts. As a glaucoma specialist and researcher who has co-authored studies on home-based tonometry, Dr McGlumphy is familiar with the benefits and pitfalls of using rebound vs applanation tonometry. “It’s not an exact surrogate for Goldmann applanation, but it’s good for examining trends,” Dr McGlumphy said.   

Research supports Dr Miller and Dr McGlumphy’s assertions that clinical visits alone cannot account for diurnal variations. “In fact, IOP recorded during office hours is significantly less, approximately 5 mm Hg, than when recorded at night,” a 2019 study explains.⁸ Similarly, patients with normal tension glaucoma experience their peak IOP outside of traditional clinic hours, bringing the significance of in-office measurements into question.⁹ Having constant access to these IOP readings may allow clinicians to monitor IOP fluctuations throughout the course of a day, but clinicians must have confidence in the patient’s ability to use these devices to ensure accurate readings. 

“To use an old computer phrase, garbage in, garbage out,” Dr Miller said. “While devices like a home iCare are user friendly, they still do require some skill and can give aberrant readings. A home environment makes it harder to assess the validity of the measurements.”

Dr McGlumphy explained that some of her patients obtain inaccurate measurements, which may be attributed to device or user error. “Patients need to understand there are diurnal variations,” she said and stressed that clinicians must counsel their patients to avoid unnecessary alarm. 

Physician, Adjust Thy Attitude

Not all challenges associated with at-home glaucoma monitoring are the result of patients’ behaviors. Optometrists’ attitudes and their ability to deal with change may also affect the success or failure of telemetric glaucoma management, according to Richard Madonna, OD, a professor and Director of the Office of Continuing Professional Education at the State University of New York (SUNY) College of Optometry.

“Physicians, like everyone else, are becoming ingrained in the way that they do things. So to get them to change from an in-office paradigm to one where some of their visits are done via telehealth can be difficult for some,” Dr Madonna said. 

With two-thirds of the world’s ophthalmologists residing in less than 10% of the world’s countries, telemetric glaucoma monitoring may expand healthcare to individuals who lack access to care.¹⁰ Research also suggests this technology may enable individuals to take a more active role in their care and potentially improve medication adherence.¹¹ Considering medication adherence is low among patients with glaucoma and between 24% and 59% fail to achieve the full or intended treatment effect, any strategy to improve adherence is beneficial.¹²

“These tests can be a jumping off point for patient conversation and reinforcing the key points of the patient’s glaucoma management,” Dr Miller said. 

But patients must be able to access this technology for any improvement to take place. Some marginalized members of society may face challenges in doing so, according to Dr Madonna. 

“There’s a greater prevalence of glaucoma in persons of certain socioeconomic levels, and they may be the same people who don’t have high speed internet,” he said.  

Redefining Early Glaucoma Care

Despite its challenges, telemedical glaucoma management continues to remain a viable treatment option. Research shows that telemedical glaucoma monitoring is cost effective, time saving, and demonstrates fair to good agreement with patient care compared with in-person visits.¹³  It may also prove advantageous to individuals with early glaucoma who need less frequent interactions with glaucoma specialists.¹³ 

Whether or not patients and clinicians wish to conduct intraocular pressure monitoring at a distance, “these devices are the way of the future,” according to Dr McGlumphy. “Patients have [devices] that give us real-time health data.” And for doctors who find difficulty embracing these methods, “they will need to adapt to the changing landscape of technology.”

“In the overall scheme of things, almost all types of glaucoma patients can take advantage of the advantages given by teleglaucoma,” Dr Madonna said, adding that patients who were most likely to adapt to at-home glaucoma monitoring would be “persons who are stable, persons who are less severe, and persons who have not been firmly entrenched in the glaucoma management paradigm.”  

While IOP monitoring is crucial, it is not the only measurement needed to keep patients’ glaucoma progression in check. Clinicians may also perform perimetry, gonioscopy, ophthalmoscopy, or other examinations, and telemedical monitoring options are available for some of these tests — all of which present unique advantages and challenges of their own.^{14, 15} As the glaucoma management model continues to shift toward a telehealth strategy, researchers, clinicians, and patients continue to reap its benefits and confront its challenges.