Smart Contact Lens Could Enable Wireless Glaucoma Detection

Detecting subtle increases in eye pressure can help doctors to diagnose glaucoma, however, this presents a more challenging task to monitor continuously, especially with the variety of temperatures that eyes experience. Research published in ACS Applied Materials & Interfaces describes a prototype of a smart contact lens that measures eye pressure accurately regardless of the temperature. 

Currently “air puff tests” are used during eye exams to take one-time measurements of eye pressure. Even a slight elevation in pressure could be an otherwise imperceptible symptom caused by fluid buildup around the cornea which could lead to a diagnosis of glaucoma. Over the years researchers have been trying to test methods of continuously and more comfortably detecting pressure fluctuations, but stepping outside into changing temperatures has been a challenging obstacle to overcome. Dengbao Xiao and coworkers set out to develop a contact lens that could accurately take measures and wirelessly transmit real-time signals across a range of temperatures. 

First, miniature spiral circuits with a unique natural vibration pattern were designed that would change when stretched by minute amounts, such as with changes to eye pressure and diameter. The researchers created the pressure-detecting contact lenses by sandwiching these tiny circuits between layers of polydimethylsiloxane. Then the embedded circuit vibration patterns were read wirelessly by holding a coil near the lens that was connected to a computer. The transmitted signals were observed to be unaffected by testing mimicking eye movement, and extended exposure to moisture, as well as daily wear and tear. 

The lenses were then placed on 3 individual pig eye specimens while controlling the ocular pressure and temperature, and the contact lenses monitored as well as wirelessly transmitted the pressure data from 50 to 122 degrees Fahrenheit. When the pressures were calculated from the signal of only one circuit in the lens the results deviated up to 87% from the true values, but when information from both circuits was used the pressure reading only differed by 7% from the true value because the combination removed the temperature-related errors. 

Based on their findings, the researchers believe that their dual circuit smart contact lens has the potential to be used for the early detection and monitoring of glaucoma, even when under a wide range of temperatures.