MEMS in contact lens to treat glaucoma

STMicroelectronics plans to put a micromachined sensor into contact lenses as part of a project with Sensimed to help diagnose and treat glaucoma sufferers.

The Triggerfish is based on a contact lens that contains a tiny embedded strain gauge to monitor the curvature of the eye during the course of a day, using a built-in antenna to transmit data to a datalogger.

The second most common cause of blindness around the world, Glaucoma is an irreversible progressive disease of the optic nerve that can eventually lead to blindness. Although it cannot be cured, its progress can be controlled once it is diagnosed and treated properly.

The standard test is the measurement of intraocular pressure (IOP), using an instrument known as a tonometer, during periodic visits to an ophthalmologist. However, the tonometer may fail to detect an elevated IOP, especially in glaucoma patients, because the pressure varies during the day and often peaks during sleep or outside of office hours. As a result, the disease is often diagnosed only after significant damage to the optic nerve has already occurred.

The lens is powered using the radio waves sent by a transceiver the wearer has around their neck so that it does not need to be connected to a battery. The embedded components are positioned in the lens in such a way that they do not interfere with the patient’s vision. The lens is fitted by the ophthalmologist and when the patient returns the next day the ophthalmologist removes the lens and receiver, obtaining a complete record of IOP changes over the preceding 24 hours.

“Application trials are confirming the significant benefits that our unique platform can provide and the next step is to commercialise the product to a larger number of centres in selected geographies,” said Jean-Marc Wismer, CEO of Sensimed.

Prototype versions of the Triggerfish have been used in trials in places such as the University Hospital in Geneva, Switzerland.

ST said its engineers are now working with Sensimed to convert the technology into a reliable commercial MEMS product ready for mass production. ST expects the development of the MEMS sensor to be completed in by mid-year and manufacturing to start in the third quarter. Sensimed and ST anticipate progressively rolling out the product country-by-country across Europe beginning in the autumn and entering the US market by the end of 2011.

“We have a strong focus on developing and manufacturing wireless sensor networks for diagnostics and other applications in medicine. This wireless, self-powered, on-body sensor will be used in a product that promises to greatly help the millions of people at risk and suffering from glaucoma,” said Benedetto Vigna, general manager of STMicroelectronics’ MEMS, sensors and high-performance analogue division.

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