A contact lens for monitoring IOP

Researchers from Turkey and the UK have reported on the development of a contact lens with an embedded sensor that tracks fluctuations in intraocular pressure (IOP).

The study, which was published in Contact Lens and Anterior Eye, described an experiment where six healthy volunteers wore the contact lens while subjected to conditions that induced changes in intraocular pressure. 

The volunteers, aged between 27 and 47, had no history of ocular disease or surgery. None of the study participants were habitual contact lens wearers.

They were instructed to refrain from drinking caffeine or alcohol, smoking or performing strenuous activities in the two hours before the experiment.

The participants were seated for 15 minutes in a dimly lit, quiet room before the start of the experiment, with the experiments conducted between 3.30pm and 7pm to take into account variations in circadian rhythm.

A baseline IOP measurement was taken while the participants were wearing the contact lens in a seated position.

Then they were instructed to drink 1.5 litres of water within five to ten minutes to prompt an acute increase in IOP. They were then placed in a supine position using a recliner seat.

“The initial data compared with tonometer measurements suggest that the system can be used to assess the variation of IOP continuously,” the authors highlighted.

Measurements collected by the sensor-embedded contact lens are collected using a wearable antenna patch.

In contrast to existing sensors, the electrically passive sensor does not require external electrical energy for its operation.

“This configuration is practically very advantageous as the need for electrical sources is eliminated. More importantly, the sensor is safe to wear as a contact lens,” the authors highlighted.