Blind Man's Restored Vision Is Studied

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Blind Man's Restored Vision Is Studied

August 24, 2003

By ANDREW BRIDGES, AP Science Writer

After 43 years of blindness, May can see again.

He can play soccer with his sons, enjoy movies and, for the first

time, gaze on the Sierra Nevada slopes he has expertly skied —

sightless — since the late 1970s.

But May can't recognize his sons, Carson, 11, and Wyndham, 9, by their

faces alone. The same goes for identifying , his wife of 15

years.

People " can't fathom that, " said May, who owns a company in ,

Calif., that makes navigational software for the blind.

Three years after surgery restored sight to May's right eye,

researchers say May's case shows how vision is more than just eye

function. Blindness has long-term effects on how the brain processes

information and constructs one's view of the world.

May lost his sight to a chemical explosion when he was 3 1/2 years

old. He eventually lost his left eye and remained blind in his right

until the surgery in 2000.

But testing since that surgery has showed that May's ability to

interpret what he sees through his good eye is decidedly mixed, said

Ione Fine, lead author of a study appearing in the September issue of

the journal Nature Neuroscience.

May can identify simple shapes and colors. He can interpret objects in

motion. He can spy faraway peaks. He marvels at the vibrancy of plants

and flowers unseen since he lost his vision.

But three-dimensional perception and the ability to recognize complex

objects such as the faces of family and friends remain severely

impaired. He strains to tell the difference between a man and a woman.

He describes a cube as a square with extra lines.

Written history mentions perhaps 30 people who reacquired vision after

protracted periods of blindness, said Fine, a neuroscientist at the

University of California, San Diego. She and her colleagues leapt at

the chance to study May and began testing him just months after his

cornea- and stem cell-implant surgery. The stem cells formed a

protective layer over his new cornea to prevent clouding.

" There has always been this question: What would happen if a blind man

got his vision back? Is it something innate or is it something we

learn from first principles? " Fine asked. " Is it something that

happens or is it something we learn, like language? "

Repeatedly, the researchers combined vision tests with scans of May's

brain activity to study how blindness had affected him.

When asked to identify a cube illustrated on a two-dimensional

computer screen, for example, May failed. But once Fine commanded the

cube to rotate, simulating motion in three dimensions, he immediately

recognized it.

" It was really weird to have a three-dimensional sense of something on

a flat surface, because it was such a foreign experience to someone

dominated by a tactile ability, " May said.

Scans of the region of May's brain associated with the processing of

complex forms revealed patchy responses when he was shown the still

cube.

But once the cube moved, his motion-processing region came ablaze with

activity, Fine said. That suggests the region was fully developed when

May lost his sight, Fine said.

Since May's ability to recognize complex forms showed such impairment,

it suggested that region is much slower to mature, Fine said. Once

deprived of visual experience, it likely ceases to develop and

languishes, she added.

Once deprived of visual experience, it likely ceases to develop and

languishes, she added.

Since humans constantly encounter novel objects and new faces — and

aging in familiar faces — the processing region in the brain must

remain flexible, Fine said.

Jon Kaas, a Vanderbilt University neuroscientist, said the findings

were consistent with what has been shown in studies with laboratory

animals reared in darkness or with their eyelids artificially kept

sealed shut.

Kaas, who was not connected with the study, said it was the most

thorough of its kind on an individual.

May agreed with Fine's theory that vision, like language, appeared to

be a skill honed through experience.

" I will never be fluent visually, but I get better the more I work at

it, " he said.

___

On the Net:

Mike May's New Perceptions

http://www.senderogroup.com/perception.htm