A Caltech engineering team has developed a simple yet elegant ocular implant that uses reflected light, rather than bulky electronics, to measure IOP changes.

The prototype consists of a tiny, black silicone cylinder 600 to 800 microns in diameter and 600 microns in height, with a reflective surface on the back and a deformable membrane at the front. It is designed to be inserted superficially into the cornea, wherein fluid pressure of the eye will alter the distance between the membrane and reflective surface, resulting in varied wavelengths of reflected light. A care provider uses a simple handheld device to measure the light given off by the implant, which can be directly correlated with the patient’s IOP.

"A doctor implants the sensor in the eye, and then you can scan it any time you like with a device that's as simple to use as a supermarket checkout stand's barcode scanner," said Vinayak Narasimhan, a graduate student in medical engineering who was an author in the study.

The innovative cylinder also features a rough outer surface that prevents cellular adhesion, circumventing buildup of white blood cells and attack by the immune system, which could reduce its effectiveness over time. This key feature, along with its independence from power sources, may allow it to last indefinitely inside the eye.

According to lead researcher Hyuck Choo, PhD, assistant professor of electrical engineering in the Division of Engineering and Applied Science, the design is still being fine–tuned and the implant could be ready for FDA review within a few years.

"For glaucoma patients, it's important to be able to take regular and exact measurements of eye pressure. It would be good if that didn't require constantly visiting a doctor's office," he said, adding that the team also plans to explore other materials that could further improve the device's functionality.