Darkness may help improve 'lazy eye'

Canadian researchers said kittens with the visual impairment amblyopia, or "lazy eye," had improved vision after being kept in complete darkness for 10 days. Kevin Duffy and Donald Mitchell of Dalhousie University said exposure to darkness caused some parts of the visual system to revert to an early stage in development, when there is greater flexibility. "There might be ways to increase brain plasticity and recover from disorders such as amblyopia without drug intervention," Duffy said in a statement. "Immersion in total darkness seems to reset the visual brain to enable remarkable recovery." Amblyopia affects about 4 percent of the general population and is thought to develop when the two eyes do not see equally well in early life, as the connections from the eyes to visual areas in the brain are still being refined. Researchers examined kittens with amblyopia induced by experimentally depriving them of visual input to one eye. After those animals were plunged into darkness, their vision made a profound and rapid recovery. Although darkness therapy was promising for the treatment of children with amblyopia, the researchers cautioned against trying this at home, because it is important to address the original cause of the amblyopia first, and to ensure that a period of darkness would not harm an individual's good eye. In addition, the researchers said they were still working out how much darkness was required, and for how long. The findings were published in Current Biology.