Waterloo vision scientists discover potential treatment for adults with lazy eye

February 22, 2016

A new treatment for adults with lazy eye, a condition previously thought to be treatable only in childhood, is one step closer as a result of research from the University of Waterloo in Canada and Sun Yat-sen University in China.

Waterloo vision scientist Ben Thompson with collaborators from China have shown that low voltage electric currents can temporarily improve sight in adult patients with lazy eye, or amblyopia.

"Until fairly recently, the prevailing view was that if adults couldn't develop amblyopia, they couldn't be treated for it," says Thompson. "This was the same for anyone with brain-based vision problems - they're often told there's nothing that can be done about their vision loss."

In a proof-of-concept series of experiments, Thompson and his colleagues 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 Thompson. "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 reorganise itself.

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 is an issue here in Canada, but much more so in countries where access to basic vision care for children is challenging," says Thompson.

That said, 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.

Other research groups have suggested that tDCS might also have beneficial effects in patients with vision loss due to stroke.

Thompson says these initial results demonstrate the proof-of-concept that will allow him and his research group to take the next step towards clinical trials.

"Our ultimate goal is to develop an evidence based treatment that patients can receive right in their eye doctor's office," says Thompson. "We expect there are other primary visual cortex problems that we may be able to address with this method."
Other collaborators include researchers from McGill University, University of Auckland and Hong Kong Polytechnic University.

About the University of Waterloo

University of Waterloo is Canada's top innovation university. With more than 36,000 students we are home to the world's largest co-operative education system of its kind. Our unmatched entrepreneurial culture, combined with an intensive focus on research, powers one of the top innovation hubs in the world. Find out more at uwaterloo.ca

University of Waterloo

Related Brain Articles from Brightsurf:

Glioblastoma nanomedicine crosses into brain in mice, eradicates recurring brain cancer
A new synthetic protein nanoparticle capable of slipping past the nearly impermeable blood-brain barrier in mice could deliver cancer-killing drugs directly to malignant brain tumors, new research from the University of Michigan shows.

Children with asymptomatic brain bleeds as newborns show normal brain development at age 2
A study by UNC researchers finds that neurodevelopmental scores and gray matter volumes at age two years did not differ between children who had MRI-confirmed asymptomatic subdural hemorrhages when they were neonates, compared to children with no history of subdural hemorrhage.

New model of human brain 'conversations' could inform research on brain disease, cognition
A team of Indiana University neuroscientists has built a new model of human brain networks that sheds light on how the brain functions.

Human brain size gene triggers bigger brain in monkeys
Dresden and Japanese researchers show that a human-specific gene causes a larger neocortex in the common marmoset, a non-human primate.

Unique insight into development of the human brain: Model of the early embryonic brain
Stem cell researchers from the University of Copenhagen have designed a model of an early embryonic brain.

An optical brain-to-brain interface supports information exchange for locomotion control
Chinese researchers established an optical BtBI that supports rapid information transmission for precise locomotion control, thus providing a proof-of-principle demonstration of fast BtBI for real-time behavioral control.

Transplanting human nerve cells into a mouse brain reveals how they wire into brain circuits
A team of researchers led by Pierre Vanderhaeghen and Vincent Bonin (VIB-KU Leuven, Université libre de Bruxelles and NERF) showed how human nerve cells can develop at their own pace, and form highly precise connections with the surrounding mouse brain cells.

Brain scans reveal how the human brain compensates when one hemisphere is removed
Researchers studying six adults who had one of their brain hemispheres removed during childhood to reduce epileptic seizures found that the remaining half of the brain formed unusually strong connections between different functional brain networks, which potentially help the body to function as if the brain were intact.

Alcohol byproduct contributes to brain chemistry changes in specific brain regions
Study of mouse models provides clear implications for new targets to treat alcohol use disorder and fetal alcohol syndrome.

Scientists predict the areas of the brain to stimulate transitions between different brain states
Using a computer model of the brain, Gustavo Deco, director of the Center for Brain and Cognition, and Josephine Cruzat, a member of his team, together with a group of international collaborators, have developed an innovative method published in Proceedings of the National Academy of Sciences on Sept.

Read More: Brain News and Brain Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.