Home-monitoring devices offer better insight to figure out IOP

Ambulatory monitoring of intraocular pressure (IOP) will present some challenges, but with it, a wealth of information that should lead to increased understanding of glaucoma and better patient care.

“Some ophthalmologists may be concerned about the number of patient phone calls home IOP monitoring could generate and wonder how they will analyze and interpret all of the data points that are produced,” said L. Jay Katz, MD. “We all know how critical IOP measurement is in managing glaucoma, and it is difficult to argue against the many positive aspects of getting more IOP information.”

Dr. Katz outlined the benefits of home IOP monitoring at the Glaucoma Symposium during the 2017 Glaucoma 360 meeting. He is director, Glaucoma Service, Wills Eye Hospital, and professor of ophthalmology, Thomas Jefferson University, both in Philadelphia.

Multiple benefits

Dr. Katz said that home IOP monitoring will give insight as to the patient’s true peak IOP and pattern of diurnal fluctuation. The data collected will allow determination of IOP parameters that predict glaucoma progression. In addition, this technology could conserve limited healthcare resources and allow for cost-effective delivery of care.

“Data from home IOP monitoring will minimize the need for office visits that are scheduled solely for IOP measurement and enable more timely adjustment of medication,” Dr. Katz explained, adding that he is already modifying management through telephone-only interactions for patients based on home measurements.

Information from 24-hour IOP monitoring also will enable the identification of patients who are non-adherent with medical therapy. At the same time, it might promote better adherence by making patients partners in their own care, he added.

“Don’t underestimate the value of having patients participate in monitoring their IOP,” said Dr. Katz. “Many of my patients want to check their IOP at home, and in a study evaluating an instrument for home tonometry, patients felt less anxiety about their glaucoma and enjoyed being involved in the process.”

Existing/emerging technology

Existing/emerging technology

In the United States, there is currently two devices available for home IOP monitoring. One is a contact lens-based system (Triggerfish, Sensimed) that is worn for 24 hours and measures change in the radius of corneal curvature that correlates with changes in eye pressure.

In explaining how the system may impact care, Dr. Katz cited results from a recent study that enrolled participants without glaucoma who had normal IOP and individuals who were normal tension glaucoma suspects. While the two groups had similar IOP at baseline, data from the contact lens sensor showed IOP fluctuation was much higher in the normal tension glaucoma suspect group.

“In a patient who is a normal tension glaucoma suspect based on appearance of the disc without definitive visual field loss, information on diurnal fluctuation may lead the clinician to lean towards treatment initiation,” Dr. Katz said.

A rebound tonometry-based device that can be used at home for self-monitoring of IOP is available in Europe (Icare Home, Icare). In the United States it was sold initially as an in-office version (Icare, Icare). (The home-use model received FDA marketing clearance in March 2017.) The tonometer gives intermittent readings rather than continuous measurements.

“This technology is ideal for at-home IOP measurement because it does not require any topical anesthetic and gives patients the ability to check their IOP at any time,” Dr. Katz said.

Available study results indicate it has reasonable performance. In one study, about 75% of the IOP readings produced were within a few mm Hg of measurements obtained with Goldmann applanation tonometry. Even though the device is straightforward to use, about 25% of patients were not able to use it successfully at home after participating in a training session.

A study investigating the device in patients with normal tension glaucoma showed how it could impact clinical care. In that investigation, the IOP measurements obtained outside usual office hours were higher than those measured in the office.

Based on this information, treatment was modified for over 50% of the participants.

Other technology

Other technology

Other companies are developing implantable devices for permanent continuous IOP monitoring. Two manufacturers that have information about their technology are Implandata Ophthalmic Products and AcuMEMS, Dr. Katz said.

Implandata is working on two versions of its device, which is called EyeMate. One version uses a sensor placed in the sulcus during cataract surgery and the other is designed for subconjunctival or subscleral implantation.

AcuMEMS is developing two versions of its device, the iSense System. One version is placed with an intraocular lens into the capsular bag after cataract surgery and the other is for anterior chamber placement at the time of a stand-alone glaucoma procedure.

Both manufacturers have completed animal studies that had positive results, and Implandata has begun clinical trials.

L. Jay Katz, MD

E: ljaykatz@gmail.com

Dr. Katz has no relevant financial interests to disclose.