American scientists have designed an adhesive gel that can seal wound or ulcers on the surface of the eye, thus sparing the need for eye surgery.

The study published on March 20 in the journal "Science Advances" showed that the gel packed with light-activated chemicals can not only close the defect but also regenerate it, Xinhua news agency reported. "We wanted this material to allow the cells of the cornea to mesh with the adhesive and to regenerate over time to mimic something as close to the native cornea as possible," said the paper's co-corresponding author Reza Dana, a professor of ophthalmology at Harvard Medical School.

The gel is clear and viscous in a dropper or syringe, but when exposed to blue light in a short time, it hardens to take on features of a native cornea, and the the cornea cells gradually grow into and become one with the gel, according to the study. The gel is the first to use visible blue light as opposed to ultraviolet light, which carries a level of toxicity.

In a preclinical study, the researchers administered the gel at 20 per cent concentration to corneal defects of 3 mm, and applied visible light for four minutes, leading to a firm adhesion to the defect. One day later, they observed a transparent, smooth eye surface without inflammation. Over time, the tissue regenerated and the new tissue showed few differences with the native one, according to the study. The researchers expected to start clinical trials to test the technology in human patients in approximately one year.

Corneal injuries are a common cause of visual impairment worldwide, with more than 1.5 million new cases of corneal blindness reported every year. Some of them require corneal transplants that carry risks of post-transplant complications like infection or rejection.