Mild electrical stimulation of the brain could help treat lazy eye

Mild electrical stimulation of the brain could help treat lazy eye

Lazy eye is a loss of vision that originates in the brain. It affects up to three per cent of Canadians and is caused by the presence of unequal images in the two eyes during childhood, typically due to an eye turn or one eye being long sighted.

The unequal input can cause the brain to process information from the weaker eye incorrectly. Unless the brain processing issue is treated, the vision loss remains, even after the problems in the eye are fixed. If left untreated, lazy eye increases a patient's lifetime risk for legal blindness by 50 per cent.

Amblyopia in children is very treatable because their brains are so responsive. It's a different story for adults whose brains have long passed out of the critical developmental period. Differences in the images seen by each eye that occur in adulthood do not result in amblyopia.

In a proof-of-concept series of experiments, researchers exposed patients to twenty minutes of transcranial direct current stimulation (tDCS) applied to the surface of the head, directly over the primary visual cortex.

They found the treatment temporarily increased the response of that part of the brain to visual information from the lazy eye. tDCS also improved patients' ability to see low contrast patterns.

Their results were published this month in Scientific Reports, a highly cited Nature publication.

"It's a long held view that adults can't be treated for lazy eye because their brains no longer have the capacity to change," says the author. "We demonstrate here that adults do have the capacity, especially when it comes to vision."

Methods such as transcranial direct current stimulation (tDCS) have recently been shown to increase adult neuroplasticity - the brain's ability to rewire and reorganize itself.