Although there already are “smart” contact lenses that monitor the eyes for signs of glaucoma, the devices are typically only worn when the patient is awake. A new type of contact lens, however, watches over the eyes throughout the night, too.
If someone is at risk of developing glaucoma, it’s important to detect the disease as early as possible. And likewise, if a patient is already in the early stages of glaucoma, it’s very important to monitor the diseases’s progression. In either case, watching for symptoms like elevated intraocular pressure (IOP) and irregular eye movement (EM) is key.
As mentioned, scientists have developed contact lenses that monitor the eyes for these symptoms.
Because the devices don’t work when the eyes are closed, though, they’re not used when the patient is asleep. Therefore, they miss the increase in IOP which typically occurs in the early morning hours before waking. They likewise don’t catch any irregular movements which may occur during the REM (rapid eye movement) phase of sleep.
That’s where the stretchable bimodal contact lenses (BCLs) come in.
Developed by scientists at the University of Electronic Science and Technology of China, they’re approximately the same thickness as regular contacts, yet each one is made up of five stacked layers of material.
On the top and bottom are layers of soft, transparent, biocompatible PDMS silicone. Directly below and above these are two more layers – both composed of copper coils – which together serve as a capacitive intraocular pressure (CIOP) sensor. In the middle is a layer of neodymium combined with PDMS. It helps with the CIOP sensing, but also serves as a magnetic eye movement (MEM) sensor.
An external electromagnetic reader coil and a Tesla meter are able to pick up signals from the sensors in the BCL, converting them into measurable CIOP and MEM data formats. In real-world usage, that coil and meter could be built into eyeglass frames worn by the patient while sleeping.
A wirelessly linked smartphone or tablet displays the readings, highlighting any that may be abnormal.
In tests performed on human volunteers and rabbits, the technology proved to be highly accurate at monitoring IOP and EM. And importantly, in rabbit tests, the breathable contacts produced no corneal inflammation or other eye damage even after being worn nonstop for one week.
“The ability to monitor both IOP and EM continuously – even when the eyes are closed – offers a more complete picture of eye health,” says Dr. Guang Yao, co-lead author of the study. “It enables early intervention and more accurate tracking of disease progression, particularly for glaucoma patients. And because it’s wireless and wearable, it can be used comfortably at home, not just in clinics.”
The research is described in a paper that was recently published in the journal Microsystems & Nanoengineering.
Source: TranSpread via AlphaGalileo