New hope for adults with lazy eye

Low-voltage electrical currents can improve vision in adults with lazy eye, which was previously thought to be treatable only in children, according to new research.

Scientists at the University of Waterloo in Canada carried out a proof-of-concept study that exposed patients to twenty minutes of transcranial direct current stimulation (tCDS), a form of mild electrical stimulation of the brain’s primary visual cortex.

The researchers, working in collaboration with a team in China, found that the treatment temporarily increased the responsiveness of that part of the brain to visual information from the lazy eye, also improving a patient’s ability to see low-contrast patterns.

Lazy eye, or amblyopia, develops in childhood. It results from the visual cortex receiving unequal images from the eyes due to an eye turn or one eye being long-sighted. It affects an estimated one in 40 children in the UK.

The disorder is easily corrected in children due to the ability of a developing brain to readjust to the visual information it receives. However, developed adult brains have lost this ability and so do not respond to conventional treatment.

The new research, published in the journal Scientific Reports, demonstrates that tCDS therapy increases neuroplasticity in adults, meaning that developed brains are able to be reorganised and rewired in a similar way to those that are still developing.

Lead researcher, Dr Ben Thompson, said the results show that amblyopia can be treated in adult patients.

Dr Thompson commented: “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.”

He added: “We demonstrate here that adults do have the capacity, especially when it comes to vision.”

Transcranial direct current stimulation is currently occasionally used as a treatment for depression. Side effects, including skin irritation, nausea and headaches can sometimes occur as a result of the procedure.

The researchers will now focus on using the study to develop a useable treatment for adults with amblyopia.

Image credit: University of Waterloo