WIRELESS MEASURING CONTACT LENS

 

Monitoring IOP is a useful method to obtain a continuous record of the glaucoma patient’s response to medications. In this regard smart contact lenses have been developed which monitor IOP constantly. However, these lenses have been found to be sensitive to environmental conditions, especially temperature fluctuations. Xiao and co-workers have developed an intelligent wireless measuring contact lens (WMCL) incorporating a dual inductor−capacitor−resistor (LCR) resonant system to achieve temperature self-compensation for quantitative IOP monitoring in different application environments.

The researchers designed two miniature spiral circuits, each with a unique natural vibration pattern that alters when stretched by minute amounts, such as with changes to an eye’s pressure and diameter. They sandwiched these tiny circuits between layers of polydimethylsiloxane, a commonly used contact lens material, to create pressure-detecting contact lenses. The two circuits enable the integration of low-frequency and high-frequency resonators within a single layer of a sensing circuit without causing visual impairment.  

Fluctuations in IOP can induce changes in the curvature of the contact lens. These changes lead to variations in the shape or position of the coil, subsequently causing changes in inductance and resulting in shifts in resonance frequency. Inductive IOP sensors integrate the sensor with the internal antenna, simplifying circuit design and reducing fabrication complexity and costs. The vibration patterns are sent wirelessly to a computer which monitors the IOP. The lens was found to be more sensitive in monitoring changes compared to other smart contact lenses.

The lenses have been tested in animal eyes and found to be effective in temperatures ranging from 12- to 50-Fahrenheit. According to the researchers, the linear combination of the dual resonators can eliminate the impact of temperature variations on measurement accuracy. The lenses were effective even when the internal temperature variations exceeded 10-degree centigrade.

The researchers claim that the WMCL has immense potential as the next generation of all-weather IOP monitoring devices.

REFERENCE:

Li X, Chen W, Li H, Shen B, He J, Gao H, Bin F, Li H, Xiao D. Temperature Self-Compensating Intelligent Wireless Measuring Contact Lens for Quantitative Intraocular Pressure Monitoring. ACS Appl Mater Interfaces. 2024 May 1;16(17):22522-22531. doi: 10.1021/acsami.4c02289. Epub 2024 Apr 23. PMID: 38651323.