Carle opthamologist Dr. Leanne Labriola, Illinois visiting scholar Ketan Dighe and professor Dipanjan Pan

A new point-of-care device could soon detect eye injury within minutes – a time frame crucial to treating eye trauma – simply by picking up levels of a key marker in a teardrop.  

University of Illinois researchers developed a gel laden with gold nanoparticles that changes colour when it reacts with a teardrop containing ascorbic acid, a marker which the groups says they have previously found to be a good measure for determining the extent of injury to the eye.

In a new study published in the journal Biosensors and Bioelectronics, the researchers used the sensor, called OjoGel, to measure ascorbic acid levels in artificial tears and in clinical samples of fluid from patients’ eyes.

“We expect a significant potential impact of this biosensor for evaluating the eye in post-surgical patients as well as trauma patients,” said University of Illinois bioengineering professor Dipanjan Pan, who led the study.

Pan’s group collaborated with  Carle Foundation Hospital ophthalmologist, Dr Leanne Labriola, to develop OjoGel.

“OjoGel technology may allow for faster identification of serious eye injuries,” Dr Labriola said. “With a rapid point-of-care device such as this, anyone in an emergency department could perform a test and know within minutes if the patient needs urgent surgery to save their vision.”

Ascorbic acid, also known as vitamin C, is found in high concentrations in the fluid inside the eye, called aqueous humour, but normally has very low concentration in tears.

“Deep damage to the cornea from trauma or incisional surgery releases aqueous humour into the tear film, which increases the concentration of ascorbic acid in tears to a measurably higher level than that found in normal eyes,” said Pan. “OjoGel offers a unique biosensing technique that provides an effective and simple method for testing ascorbic acid in a point-of-care delivery system.”

A tiny teardrop is all that’s needed to cause a colour-change reaction in the OjoGel. The extent of the colour change correlates to the concentration of ascorbic acid in the tear sample, shifting from pale yellow to a dark reddish-brown as the concentration increases.

The researchers did extensive testing to determine the concentrations associated with each degree of colour change. They developed a colour key and guidelines for using the mobile phone app Pixel Picker to precisely measure the concentration indicated by a reacted gel sample.

The researchers say they plan to continue refining OjoGel technology in hopes of producing a low-cost, easy-to-use clinical device. They also will perform clinical studies to determine whether OjoGel readings reliably evaluate eye damage.