A visually demanding video game can end in disaster in, literally, the blink of an eye, so many players adopt a simple unconscious strategy to ensure they are not taken by surprise: They do not blink.

Alfredo Sadun, M.D., Ph.D., the Flora L. Thornton Chair in Vision Research and professor of ophthalmology and neurosurgery at the Keck School of Medicine of USC, says that as a result, players-most commonly young adults and children, risk dry and irritated corneas. In rare, extreme cases, prolonged dryness can result in scarring that can
only be treated with a corneal transplant.

"Nature has evolved a system of regular blinking to keep the eye moist and healthy," he says. "But at the same time, it's no good to have your eyes closed when you have a saber-tooth tiger jumping out at you, so nature ensures that when you are strongly focused on something visual, it relaxes the need to blink."

The problem is that "in video games, something is always jumping out at you. And when kids play for hours on end, the cornea gets dry enough to irritate the eye," Sadun says.

Interestingly, the problem is not limited to video games. Anything that engrosses visual attention such as a compelling novel or computer work can have the same effect on readers of any age, he adds.

Sadun notes that preventing dryness can be as simple as taking regular breaks to blink or applying eye drops. to keep the cornea moist.