Violent "shooter" video games can improve the sight of adults afflicted by cataracts since birth, a study has found.
The games, which typically involve gunning down bandits or enemy soldiers before they can shoot first, appear to "rewire" parts of the brain's visual cortex. Scientists think the visual challenges of surviving in a threatening virtual environment can repair damaged neurons.
The discovery came after an experiment involving six adults aged 19 to 31 who had been born with congenital cataracts which cloud the eyes. Follow-up studies suggest that the improvements are long-lasting.
Being deprived of visual stimulus early on has a long-term effect on the brain. Even after having their vision corrected with surgery and contact lenses, children with the condition can end up with permanently poor sight.
The study showed that some of these effects can be reversed by a short programme of video gaming.
Psychologist Dr Daphne Maurer, from McMaster University in Canada, who led the research, said: "After playing an action video game for just 40 hours over four weeks, the patients were better at seeing small print, the direction of moving dots, and the identity of faces.
"Those improvements tell us that the adult brain is still plastic enough to be trained to overcome sensory deficiencies."
Not any video game will do. It has to be the kind of game that involves vigilance, recognising contrasts of light and shade, and spotting events happening at the edge of vision. These are just the kind of skills needed in "first person shooter" games.
All the study participants improved their ability to perceive lower contrasts and notice subtle differences among faces and moving objects, said Dr Maurer at the annual meeting of the American Association for the Advancement of Science (AAAS) in Vancouver, Canada.
"On an eye chart, you have a chart of letters, and we ask you to read down," she said. "Our patients could go one or two lines farther after playing 10 hours of video games a week for four weeks."