An implantable microchip that provides 24-hour monitoring of fluid pressure in the eye is described in a study published online this week in Nature Medicine. The technology, which uses a cell phone camera equipped with an optical adapter, was tested in pigs, and could provide crucial readouts about pressure fluctuations in the eye.
Elevated fluid pressure in the eye, called intraocular pressure (IOP), and more specifically, wide daily fluctuations in IOP (with peak levels often occurring at night when a person is lying face-up and asleep) are known to be risk factors for the progression of glaucoma. Worldwide, glaucoma affects 65 million people and is one of the leading causes of blindness. The current gold standard for IOP measurement is Goldmann applanation tonometry, but this procedure must be carried out by an eye care professional and requires the use of topical anesthesia. As these measurements can only be taken during visits to the doctor’s office, they are insufficient to accurately track fluctuations in IOP for the purposes of glaucoma diagnosis, management and follow-up during drug treatment, or after surgery.
Yossi Mandel, Stephen Quake and colleagues devised a microfluidic pressure sensor that can be implanted as a standalone device in the eye or incorporated into a lens that is routinely implanted into the eye during cataract surgery. A cell phone equipped with an optical adaptor can then be used for image capture and immediate analysis. The group has successfully tested the device in surgically removed pig eyes, however clinical trials are necessary to confirm its application as a self-monitoring IOP device for the management of glaucoma.