In recent years, we've heard of at least two different implants designed to measure the intraocular pressure in glaucoma patients' eyes, potentially preventing blindness. Yet another such implant, this one known as Eyemate, recently became commercially available in Europe.

Glaucoma typically occurs when a blockage in the eye's drainage channels causes aqueous humor fluid to accumulate within the eye faster than it can drain out. This leads to an increase in intraocular pressure, which can in turn damage the optic nerve, resulting in permanent loss of vision.

It's therefore important for patients to have that pressure checked regularly, so that any significant increases can be addressed via measures such as changes in medication, or even surgery. Unfortunately, though, these pressure-checks have to be performed at an ophthalmologist's office, and thus usually only take place a few times a year. Any fluctuations in intraocular pressure that occur between those visits will simply be missed.

It was with this problem in mind that Eyemate was created. Designed via a collaboration between Germany's Implandata Ophthalmic Products and the Fraunhofer Institute for Microelectronic Circuits and Systems, the thin and flexible ring-shaped implant can be placed behind the eye's iris during standard cataract surgery – it goes in through the same incision that is used to remove the eye's clouded natural lens, and to insert its artificial replacement.

Patients are subsequently able to perform pressure readings as often as they wish, within their own home.

This is done using a handheld reading device which is held up to the eye without contacting it, temporarily powering the implant by delivering a 2-second weak magnetic pulse. The implant proceeds to measure the intraocular pressure and temperature, and transmits that data back to the reader. Users see the numerical reading on the reader's digital display, plus they're able to upload it to a secure online database that can be accessed anytime by their physician. Additionally, they can use an app to track their readings over time.

After a successful clinical study conducted at several German hospitals, Eyemate received CE approval in the middle of last year. It was commercially launched in Germany, Austria and Switzerland this April. The designers are now working on making it smaller, and on simplifying the implantation procedure.

Fraunhofer has also been working on an implant that not only monitors intraocular pressure, but that could also lower that pressure by pumping out fluid as needed.

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