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.