Electronic sensor “in your eye” helps in treating glaucoma

Citation

Bloss, R. (2011), "Electronic sensor “in your eye” helps in treating glaucoma", Sensor Review, Vol. 31 No. 3. https://doi.org/10.1108/sr.2011.08731caa.007

Electronic sensor “in your eye” helps in treating glaucoma

Article Type: New products From: Sensor Review, Volume 31, Issue 3

A Swiss firm, SENSIMED AG, has developed the SENSIMED Triggerfish^®, a wearable “in your eye” sensor system, to continuously measure intraocular eye pressure to aid in treatment of glaucoma. The system includes a custom soft contact lens, a small wearable electronic controller and a disposable adhesive antenna worn around the eye during the monitoring session. Glaucoma, resulting from elevated or fluctuating eye pressure, is the second leading cause of blindness, effecting about 67 million people worldwide. Elevated or unstable pressure inside the eye results in damage to the optic nerve ultimately leading to blindness.

Traditional glaucoma treatment has required the eye doctor to have the patient come into the office periodically for an intraocular pressure measurement. The first line of treatment is a prescription eye drop. But previously, the doctor was unable to monitor pressure variation, which might occur during everyday activities when using the drops. Now, a custom contact lens fitted with an MEMS chip and a platinum strain gauge can monitor eye pressure. At last, a wearable sensor approach that can provide that 24-h information for better monitoring and treatment.

The contact lens (Figure 1) wirelessly communicates with the recorder. It harvests radio energy from the adhesive antenna. This energy powers the custom ASIC micro-processor that monitors the strain gauge rings affixed to the outer diameter of the contact lens. The tensometer strain gauge detects even the slightest changes in the intraocular eye pressure continuously for 24 h. This data are sent wirelessly to the adhesive antenna worn by the patient.

Figure 1 Closeup of the soft contact lens with antenna, strain gauge sensor rings and the MEMS chip

The soft disposable silicon contact lens does not obstruct the patient’s vision. The contact lens is 14.1 mm in diameter. The attached MEMS chip is but 2 mm² and only 50-μm thick. The outer diameter of the lens holds the ring-like micro-antenna and the twin ring platinum strain gauge. The center area of the lens is clear for normal patient vision.

The wearable controller is about 62 by 106.5 mm and 16-mm thick (Figure 2). It is worn in an in an over-the-neck cloth pouch. The controller is powered with a rechargeable battery pack. Functions in the controller include wirelessly transmitting the energy to power the sensor, continuously receiving the eye pressure data, storing this data and later transmitting the data on demand via a Bluetooth(r) USB adapter to the doctor’s computer for analysis. The onboard battery holds a charge adequate for the 24-h monitoring period. After the data readout, the unit is recharged.

Figure 2 The SENSIMED Triggerfish^® controller

Communication between the contact lens and the controller is via a plug in external adhesive-loop antenna that leads up to the face and is worn around the eye during the monitoring session. The lens and the antenna are both single use, disposable devices. The controller remains with the doctor and is reused for subsequent patients.

For more information on the SENSIMED Triggerfish^® system, please visit the web site: www.sensimed.com

Richard BlossAssociate Editor

The photos were furnished by and are ©by SENSIMED AG.