IntraOcular Pressure (IOP) monitoring is an essential diagnostic tool for the efficient treatment of glaucoma and other ocular hypertension-related diseases. Clinical trials have shown that frequent IOP monitoring can decelerate the progress of glaucoma and minimize optical nerve damage Current IOP monitoring technologies (e.g. tonometry) are non-invasive and simple to execute, but they are not accurate and not suitable for life-long and frequent IOP monitoring: they require a visit to the hospital or to a clinic as the measurement is performed by trained personnel. We propose a 'Near Infrared Fluorescent-based Optomechanical'(NiFO) IOP sensing technology for accurate, home-based, IOP monitoring for patients with moderate or severe glaucoma. The NiFO technology is based on an electronic-free MicroElectroMechanical Systems (MEMS) implantable sensor (termed the 'NiFO sensor') that converts IOP changes into a dual-wavelength optical signal in the near infrared (NI) regime. The NiFO sensor is integrated into an intraocular lens or surgically attached on the iris and therefore permanently implanted into the patient's eye. An external, portable optical readout system (ORS) is used to excite the NiFO sensor, collect and analyze the emitted NI optical signal. The power-free NiFO sensor permits frequent and life-long IOP monitoring, allows the patient to perform the IOP measurement at home, requires no maintenance (e.g. battery replacement), it is accurate and it has a very small size (<0.5 mm3) and footprint (~0.25 mm2). Our research plan consists of the following aims: 1) Microfabrication and in vitro testing of the NiFO pressure sensor. The NiFO sensor, consisting of a silicon/PDMS chip will be microfabricated using standard bulk and surface silicon micromachining processes. Its specifications (dynamic range, precision error, etc) will be established in vitro by immersing the NIFO sensor into a bath filled with aqueous humor. 2) Construction of the Optical Readout System (ORS). A portable optical readout system consisting of an optical head and an excitation/detection unit will be manufactured. The system will integrate all the optics needed to excite the NiFO sensor, collect analyze the emitted NI fluorescence signal. The proposed technology will help in efficiently managing and treating glaucoma and hypertension-related diseases and it will trigger the development of other implantable, power-free, miniaturized devices that can be used in a variety of pressure monitoring biomedical applications.
Intraocular pressure (IOP) monitoring is an important diagnostic tool for accessing the pathological condition of patients with chronic glaucoma. This work aims to develop a new class of point-of-care, implantable IOP monitoring sensors that will provide better management and efficient treatment for such patients.