Managing Glaucoma Patients in the COVID-19 Era

Disruptions in health care caused by the COVID-19 pandemic have created opportunities for patients, physicians, and medical technology companies to embrace and enhance virtual care. With new tools in hand, it behooves us to limit in-office visits when feasible in order to reduce the spread of disease. This article examines some of the technologies that may help us to glimpse a future of remote glaucoma monitoring, which could serve current demand, reduce the annual number of in-office visits for each patient, and potentially improve glaucoma care.

REMOTE IOP MONITORING

IOP is the only modifiable risk factor for managing and controlling the progression of glaucoma, yet the efficacy of our treatments is based only upon a few IOP readings taken annually at visits. Because of this, we often aren’t able to determine a patient’s peak IOP. More than 50% of patients’ peak pressures occur outside of office hours.¹ In one study, almost 10% of patients with normal-tension glaucoma who never had IOP higher than 21 mm Hg during clinic hours registered IOPs higher than 23 mm Hg during the nocturnal period.² Additionally, clinicians have limited information regarding diurnal variation. Relative risk of disease progression at 5 years in one study was roughly six times greater for eyes with IOP fluctuation of 5.5 mm Hg compared with those with IOP fluctuation of 3 mm Hg.²

With this is mind, we can surmise that our few annual in-office IOP checks may be inadequate in determining the effectiveness of IOP control, and home monitoring could provide superior insights into the efficacy of our treatments. Two devices for monitoring a patient’s IOP remotely have been developed.

Portable Tonometry

The iCare Home Tonometer (Centervue) is a portable rebound tonometer that received FDA clearance in 2017. Patients can be taught to use the device in the office, and one study found that more than 90% of patients were able to use the device accurately.³ The iCare Home tonometer has shown good repeatability and correlation with Goldmann applanation tonometry.⁴

Cvenkel et al used the iCare Home to evaluate diurnal IOP and to assess whether there were differences in IOP parameters (mean IOP, peak IOP, fluctuation of IOP as range, and standard deviation of IOP) between progressing and stable eyes. They found that eyes with glaucomatous progression had greater IOP fluctuation, higher peak IOP, and higher mean IOP. The authors concluded that self-monitoring of IOP provided more complete data on variability of IOP than in-office monitoring alone to assist in the management of glaucoma.⁵

Contact Lens Sensor

The Sensimed Triggerfish continuous ocular monitoring system (Sensimed) is an FDA-cleared device that consists of a soft disposable silicone contact lens designed to remain on the eye surface for 24 hours. Strain gauges embedded within the lens transmit information about ocular volume changes throughout the day and night to an adhesive antenna attached around the orbit of the patient. These changes correlate with relative changes in IOP. Dunbar and colleagues have found the system to be useful in identifying high risk patients and monitoring response to treatment.⁶Note: The Sensimed Triggerfish system is not commercially available in the United States.

PORTABLE VISUAL FIELD TESTING

Visual field testing is the only direct method to measure functional defects in glaucoma. Prompt detection of glaucomatous progression is critical for preservation of vision. Inadequate testing frequency and test-to-test fluctuations are limitations in analysis for progression.⁷ Home monitoring may allow more regular testing and provide enhanced ability to detect true changes.

Suprathreshold Screening

The Moorfields Motion Displacement Test (MMDT) is a suprathreshold screening test for visual field assessment using moving line stimuli displayed on a standard laptop computer. Ong et al conducted a study to evaluate the diagnostic performance of the MMDT for discriminating between healthy and glaucomatous eyes. Glaucomatous eyes were defined by abnormal Heidelberg Retina Tomograph I (Heidelberg Engineering)-based Moorfields Regression Analysis and clinical examination showing optic rim thinning or cup-to-disc asymmetry > 0.25. MMDT demonstrated good correlation in diagnosing glaucoma when compared with the structural criteria.⁸

Perimeter App

The Melbourne Rapid Fields (MRF) is an iPad-based perimeter application that allows remote visual field testing. Using a modified 24-2 grid, the software implements fixation monitoring, and false positive and false negative checks are presented throughout the test. MRF perimetry has been shown to provide results reasonably comparable to those of the Humphrey Field Analyzer (Carl Zeiss Meditec).⁹ That said, MRF and the Humphrey Field Analyzer cannot be used interchangeably on different test sessions.

CASE EXAMPLE

Remote testing may allow eye care physicians to maintain the standard of glaucoma care while reducing the number of annual in-person visits. But could continued advancements in at-home testing improve glaucoma care? Consider this patient.

Presentation

A 70-year-old pseudophakic White woman had been treated for ocular hypertension with travoprost ophthalmic solution 0.004% (Travatan Z, Novartis) once each night in each eye for the past 14 years. I did not initiate her treatment, but I assumed her care in 2017. Her pretreatment maximum IOP was in the upper 20s mm Hg, and her IOP had been stable in the mid-teens since the start of treatment. Her optic nerve appearance and Humphrey visual field tests had been stable and normal in each eye for many years. Retinal nerve fiber layer analysis on OCT demonstrated thinning greater in the right eye than in the left but without progression. The patient had been monitored consistently every 6 months with annual Humphrey visual fields and OCT.

The patient presented to the clinic for an unscheduled visit in December 2019 with the complaint of mild blur in her right eye but no additional symptoms. Her VA was 20/30 OD and 20/25 OS, which was stable from previous exams. Confrontation fields revealed generalized constriction in the right eye and a 2+ afferent pupillary defect in the right eye. Goldmann tonometry was 50 mm Hg OD and 16 mm Hg OS.

Slit-lamp and dilated fundus examination were stable for both eyes from previous exams, with the exception of increased cupping of the optic nerve in the right eye. Gonioscopy revealed grade 4 angles for 360˚ in each eye.

Diagnosis

The patient was diagnosed with glaucomatocyclitic crisis based on the unilateral presentation, open angles, mildly blurred vision, and absence of ocular pain. This is an atypical case due to the patient’s age and the fact that this condition is generally self-limiting. Brimonidine tartrate/timolol maleate ophthalmic solution 0.2%/0.5% (Combigan, Allergan) and dorzolamide HCl 2% (Trusopt, Santen) were instilled every hour in the office until the patient’s IOP decreased to a reasonable level. She was allowed to return home once her IOP reached 26 mm Hg. She was instructed to use travoprost in both eyes at bedtime, brimonidine/timolol and dorzolamide both twice daily in the right eye, and prednisolone acetate ophthalmic suspension 1% (Pred Forte, Allergan) four times a day in the right eye, and to return for follow-up the next day.

Follow-Up

At that follow-up visit, the patient stated that vision with her right eye seemed modestly improved. However, the IOP had increased to 34 mm Hg OD. After consulting with the patient’s nephrologist, oral acetazolamide 500 mg twice daily was added to the drop regimen. The patient’s IOP was 20 mm Hg on a subsequent return visit, but visual field testing revealed a drastic change (Figure). As a result, I referred the patient to a glaucoma specialist for additional treatment considerations.

Referral

The patient presented to the glaucoma surgeon with an IOP of 17 mm Hg OD, and the surgeon chose to continue the current treatment and monitor the patient closely. At 1-month follow-up, the patient’s IOP had increased to 37 mm Hg with further glaucomatous cupping of the optic nerve. The decision was made to proceed with incisional surgery using an Ahmed Glaucoma Valve (New World Medical) and scleral graft.

TO THE FUTURE

The patient’s surgery was successful, and her IOP has since been stable at 15 mm Hg. Although she has experienced no further progression of visual field loss, I continue to give thought to the notion that her earlier visual status could have been preserved with remote monitoring of her IOP and visual fields. I believe that in the future we will be able to provide better, more timely care to our glaucoma patients with the use of at-home testing.