MEMS Sensor-Glasses Pair for Real-Time Monitoring of Intraocular Pressure

We present a novel implantable MEMS sensor - readout glasses pair towards the real-time monitoring of intraocular pressure. The overall system comprises i) a diffraction grating interferometric MEMS sensor to be embedded in the cornea and ii) readout glasses embedded with a laser diode, miniaturized aspheric lenses, and a CMOS camera. Owing to the abundance of diffracted orders, the proposed intraocular pressure measuring system offers ±8 degrees of eye tilt tolerance during monitoring via the camera. Furthermore, the use of one or multiple reference gratings adjacent to the sensor mitigates the effects of altering optical power (due to eye motion or laser noise) on the sensor. The design of the proposed device is justified with the analytical modeling of diffracted orders from the pressure sensor and ray-tracing simulations of the readout glasses. Through in-vitro measurements, we demonstrated a measurement range of $\triangle \text{P}$ = 40 mmHg pressure, with an average deflection sensitivity of 4.06 nm/mmHg and a resolution of 2.5 mmHg. With further development, the proposed system can be used for personalized real-time glaucoma monitoring.