A novel contact lens that measures intraocular pressure (IOP) continuously over 24 hours, including during undisturbed sleep, proved accurate and reliable in a first in-human feasibility assessment.1
The noninvasive pressure-measuring contact lens (PMCL) measures IOP in mm Hg as well as ocular pulsation. (The latter’s role in glaucoma pathogenesis remains controversial.)
“A 24-hour IOP curve could positively impact management of patients with glaucoma, especially those with functional/structural signs of progression despite apparently well-controlled IOP,” said Kaweh Mansouri, MD, MPH, at the Montchoisi Clinic in Lausanne, Switzerland. The potential beneficiaries of 24-hour monitoring include at-risk subjects with IOP in normal range during office hours, unstable glaucoma patients showing glaucoma progression despite low target IOP, and patients with normal tension glaucoma, he said.
Proof of concept. The device includes a silicone contact lens, pressure sensor, antenna, and a telemetry microprocessor embedded in the lens. In this prospective nonrandomized trial, it was placed on the eyes of eight subjects—four with glaucoma and four without—shortly after IOP was measured by Goldmann applanation tonometry (GAT) and dynamic contour tonometry (DCT). The lens remained in place for 24 hours, after which researchers compared its IOP values to those obtained via GAT and DCT.
As measured by the sensor, the mean IOP difference was within 5 mm Hg in 75% of subjects measured with GAT and in 87.5% of subjects measured with DCT. The IOP difference was within the requested 5 mm Hg limits for new tonometers.
Subjects also took a water drinking test, which perturbs the aqueous fluid system and may promote a rise in IOP. In the test, the PMCL detected an average IOP increase of 2.43 mm Hg, compared to 1.85 mm Hg with DCT. (GAT was not used for this test.)
Need for improvement. After the sensor was removed, 75% of eyes had transient corneal erosions; of these, 33.3% were mild, 50% were moderate, and 16.7% were severe. All resolved with or without medication after a mean of 3.1 days. Patients rated PMCL tolerability somewhere in the middle, with a mean score of 55.5 on a scale from 0 (no discomfort) to 100 (severe).
The next step is to test a second-generation device, which was designed to enhance safety and tolerability and increase accuracy of the measurements, Dr. Mansouri said.
1 Wasilewicz R et al. Br J Ophthalmol. Published online Feb. 19, 2020.
Relevant financial disclosures—Dr. Mansouri: Implandata: C; Sensimed: C.
For full disclosures and the disclosure key, see below.
Full Financial Disclosures
Dr. Busch None.
Dr. Li Wuhan Neurophth Biotechnology: S.
Dr. Mansouri Alcon: L, Allergan: C,L; Bayer: S; Implandata: C; Glaukos: S; Novartis: L; New World Medical: C,L; Optovue: L,S; Santen: L,S; Sensimed: C; Thea: L; Topcon: L,S.
Dr. Sim Allergan: C; Bayer: C; Big Picture Eye Health: C; Haag Streit: C; Novartis: C.
||Consultant fee, paid advisory boards, or fees for attending a meeting.
||Employed by a commercial company.
||Lecture fees or honoraria, travel fees or reimbursements when speaking at the invitation of a commercial company.
||Equity ownership/stock options in publicly or privately traded firms, excluding mutual funds.
||Patents and/or royalties for intellectual property.
||Grant support or other financial support to the investigator from all sources, including research support from government agencies (e.g., NIH), foundations, device manufacturers, and/or pharmaceutical companies.
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