I-Corps: Sensing device to prevent and control glaucoma

University Of Washington, Seattle WA

Investigators

Abstract

Glaucoma is a group of diseases that can damage the eye's optic nerve and result in vision loss and blindness. Half of Americans living with glaucoma are unaware of their condition. This is because glaucoma sufferers often do not experience any symptoms until irreparable damage has occurred. Adding to this problem is the difficulty of professional diagnosis. Patients who attend all recommended eye wellness exams will see an ophthalmologist every 1-2 years, at which time they will receive a tonometry exam to check for glaucoma. A tonometry test takes a single measurement of the eye pressure, but glaucoma may remain undetected if the patient's pressure happened to fluctuate to the low end during the annual visit. In addition, irreversible damage and blindness could occur during the long time span between visits. The cost burden associated with nursing care for visually impaired and blind Americans amounts to $13.2 billion from government agencies (Medicare, Medicaid specifically), as well as an additional $1.3 billion from private insurance companies, and $5.7 billion in out-of-pocket expenses for seniors and their families. This project aims to develop a solution that offers mobile and continuous monitoring for patients at higher risk of developing glaucoma by upgrading currently implanted lenses for cataracts. Monitoring is performed by the patient placing an external readout unit in proximity to the eye. This simple add-on to an existing product and procedure will reduce the incidence and extent of blindness in glaucoma patients, and will decrease the costs associated with irreversible eye damage caused by glaucoma. The product being developed is a system that is comprised of an intraocular pressure sensor and an associated reader system that reports intraocular pressure in real-time. The product is really a two-component system formed of the pressure sensor and reader. The implantable pressure sensor is solely fabricated of biocompatible materials that form a resonating structure that changes in resonant frequency as the pressure in the eye varies. The sensor is embedded or laminated on current prosthetic lenses used in cataract surgeries. The sensor contains no power supply or internal circuit, hence it does not easily fail or get out of date. In addition, no hazardous materials are introduced in the eye. The associated reader remotely interrogates (pings) the resonant sensors by emitting a low power radio frequency (RF) signal and monitors the reflected signal from the sensor. Changes in pressure will cause the reader to read different response frequencies. The reader system will track pressure variation frequently to provide trends and will alert the patient and/or physician if the pressure increases to levels that can permanently damage the optic nerve. The intent is to create a simple reader that can be a standalone device, an add-on piece of hardware using smart phones, or a sub-system addition to wearable health monitoring systems. The scope of this proposal is to complete the development of mass producible pressure sensors, development of a reader prototype, and robustness testing of the system, most notably identifying limitations on the RF link, sensor implant reliability, and potential sensor drift or calibration issues. This product is the first of many potential systems for remotely monitoring conditions in the body using the passive RF sensors and with external readers.