Portable sensor to quickly detect severe eye injury

Researchers, including those of Indian-origin, are developing a portable sensor that can quickly and inexpensively determine whether an eye injury is mild or severe.
The device called OcuCheck measures levels of vitamin C in the fluids that coat or leak from the eye.
The sensor could speed efforts to determine the extent of eye injuries at accident sites, in rural areas lacking ophthalmology specialists or on the battlefield, the researchers said.
The new sensor uses graphene platelets that are layered one nanometre thick on filter paper.
Upper layers include a unique polymer that interacts with the graphene; gold electrodes; and ascorbate oxidase, an enzyme that binds to ascorbic acid.

"The sensor takes advantage of the fact that the ocular tear film - the viscous fluid that coats the eyeball - contains low levels of ascorbic acid, which is just vitamin C, while the interior of the eye contains much higher levels," said Dipanjan Pan, a bioengineering professor at the University of Illinois in US.

"So the concept is, if there is severe damage to the eye that penetrates deeply, the ascorbic acid will leak out in high concentration," said Pan, who is creating the device in collaboration with ophthalmologist Leanne Labriola.
Two postdoctoral researchers in Pan's laboratory, Santosh Misra and Manas Gartia helped develop the new sensor.

At present, those with eye injuries must find their way to a hospital to have their injuries assessed, which is complicated, time-consuming and imprecise.
In tests with clinical samples from 16 patients undergoing eye surgery, the team found that their sensor could - with high sensitivity, accuracy and specificity - detect a range of ascorbic acid concentrations.
No current techniques for assessing eye injuries involve measurements of ascorbic acid, researchers said.
"The idea is that the moment that the ascorbic acid comes in and binds to the ascorbate oxidase, it will pull the polymer out of its interaction with the graphene, changing the sensor's electrical properties," said Pan.

"This technology has the ability to impact a large number of patients, particularly in rural settings, where access to an ophthalmologist can be limited," Labriola added.
The findings were published in the journal Scientific Reports.