Development of a Completely Encapsulated Intraocular Pressure Sensor

Abstract

A completely encapsulated intraocular pressure (IOP) sensor equipped with telemetric signal and energy transfer is introduced integrated into a silicone disc for implantation into the eye. After implantation into enucleated pig eyes and into rabbit eyes in vivo, the IOP was recorded and compared to established techniques of IOP measurement. Pressure chamber tests showed that the sensor functioned correctly after biocompatible encapsulation in polydimethylsiloxane. In vivo and in vitro tests in rabbit and pig eyes demonstrated that the implanted system worked with the same precision as established techniques for IOP determination. The correlation between the measurements with the implanted device and pneumotonometry in several experiments was between 0.9 and 0.99. This device serves as a functioning model for the realization of a telemetric IOP sensor for integration into an artificial intraocular lens. Such a device will open new perspectives, not only in the management of glaucoma, but also in basic research for mechanisms of glaucoma.

Ambulatory 24-h intraocular pressure monitoring in the management of glaucoma

“…This pressure sensor functioned wirelessly by means of a coupled magnetic field. Others modified this approach by placing the pressure sensor in an intraocular lens (IOL) for use with cataract surgery [13,14]. Wolbarsht et al [15] proposed another approach that used an elastic band placed at the globe's equator with an embedded pressure transducer to record changes in globe diameter.…”

Grundlagen der Applanationstonometrie

“…Die Messdaten können dann auf ein Speicher-bzw. Auswertegerät übertragen werden [26]. Mit dieser Entwicklung, die nicht nur eine direkte intraokulare Druckmessung, sondern auch eine kontinuierliche Aufzeichnung des Augeninnendrucks ermöglicht, verbinden sich große Hoffnungen, da sie die beiden zentralen Wünsche an die Tonometrie, nämlich eine direkte unmittelbare Messung des intraokularen Drucks und eine kontinuierliche Druckaufzeichnung, erfüllen kann.…”

Development of a fully implantable wireless pressure monitoring system

“…Micromachined pressure sensors are readily available and have been explored for use in blood pressure measurement, either in intravascular systems or implantable pressure cuffs (Chaer et al 2006;Najafi and Ludomirsky 2004;Potkay 2008;Schlierf et al 2007;Schnakenberg et al 2003;Walton and Krum 2005;Ziaie et al 2001). Sensors are also being developed for sensing intraocular pressure, intracranial and spinal pressure, and orthopedic stresses (Chiang et al 2007;Eggers et al 2000;Leonardi et al 2003;Meir et al 2008;Tofighi et al 2006;Walter et al 2000;Yoon et al 2004). In urology, a field in which the etiology of disease is often times secondary to abnormalities in pressure, there have only been a few pressure sensors that been developed for this purpose, but to our knowledge, none have been tested successfully in vivo (Coosemans and Puers 2005;Siwapornsathain et al 2002).…”