Contact Lens Sensor Triggerfish – What Do We Know?

Abstract

Multiple measurements of the intraocular pressure (IOP) at different times during the day and at night provide information on the peak and trough values, and the number and magnitude of short- and long-term fluctuations. Goldmann applanation tonometry (GAT) is generally used only once or a few times during office hours. The ideal would be a safe, well-tolerated, and valid 24- hour measurement. The contact lens sensor Triggerfish® (SENSIMED AG, Lausanne, Switzerland) is claimed to measure changes in corneal curvature induced by changes in IOP. After animal experiments, multiple studies in healthy and glaucoma patients were performed, in some cases revealing good correlation with tonometer values, in others poor or no correlation at all. The interpretation of the 24-hour profiles is not standardised, and there is no agreement upon definition of a fluctuation. Comparability between mmHg and an electrically measured value cannot be established. Despite the fact that safety and tolerability of the device are good, the absence of definitive validation of the results means that the product cannot yet be recommended for daily clinic or office use. This product is also no longer marketed as providing ‘24- hour IOP profile’ or ‘continuous monitoring of IOP fluctuation’, but now rather as recording a ‘24-hour profile of ocular dimensional changes’.