Implantable IOP Sensor May Boost Adherence

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An implantable intraocular pressure (IOP) sensor recently earned the European Union’s CE mark after proving safe, well-tolerated, and reliable in patients with primary open-angle glaucoma.¹ Moreover, evidence suggests that the Eyemate-IO (Implandata Ophthalmic Products) may improve therapeutic intervention and patient compliance.

“There is strong anecdotal evidence—based on patient self-reporting—that the experience of seeing the IOP decrease after eyedrop application leads most patients to be more vigilant in their eyedrop use,” said Lars Choritz, MD, at University Eye Clinic in Magde­burg, Germany.

Designed for indefinite implanta­tion. The Eyemate consists of a foldable sensor ring, which is injected through a clear-corneal incision of at least 3.2 mm and then into the ciliary sulcus during cataract surgery. IOP is recorded on a battery-powered handheld reader that stores up to 3,000 pressure readings.

During a prospective observational study, the sensor was implanted in 22 patients with controlled IOP who were scheduled for cataract surgery. Patients were instructed to measure their IOP four times daily at self-determined intervals. They averaged 7.9 measures daily. There were few surgical complica­tions and no unexpected adverse events related to the device, which remained in all eyes to the end point at 12 months. Complications occurred early and were attributable to the additional manip­ulation necessary for device implanta­tion, compared to cataract alone.

Good concordance. Eyemate mea­surements were 3.2 mm Hg higher than those recorded via Goldmann appla­nation tonometry, with the difference between the two devices relatively stable over time.

The difference in readings was not unexpected, Dr. Choritz said, as “the Eyemate sensor measures absolute pressure and is unaffected by corneal parameters like central corneal thick­ness and rigidity.”

And a surprise. IOP variability in each patient surprised the researchers. Whereas conventional tonometry requires the patient to sit upright and still, the Eyemate records pressures during real-life activity. As such, it revealed short-term IOP variability within seconds and upon any type of external stimulus. “IOP variability was much greater than expected, with fluc­tuations as high as 20 mm Hg in many patients,” Dr. Choritz said.

Patients who observed the fluctua­tions began to experiment on their own to see what happens to their IOP during a range of activities—for example, when drinking coffee or lying down for a nap. Their curiosity appears to have fostered improved adherence, Dr. Choritz said.

“We believe that access to the wealth of data provided by the self-measure­ments may potentially lead to better individualization of therapy,” he added. “Future studies will show whether the increased frequency of self-measuring leads to better therapy outcomes.”

—Miriam Karmel

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1 Choritz L et al. Am J Ophthalmol. Published online Sept. 20, 2019.

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Relevant financial disclosures—Dr. Choritz: None.

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