There's more to vision than meets the eye

After surgery, a California man's eye functions perfectly. But unless his brain catches up, there's much he still can't see.

After 43 years of blindness, Michael 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 Jennifer, his wife of 15 years. He relies on cues such as hair length and color, height and gait to guess who someone is.

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

His experience strongly suggests that humans are born with some visual abilities, but probably not all of them, and that some visual skills come more readily than others. While the brain can be reprogrammed, that capacity may be limited. And the brain may permanently lose certain capabilities if they lie dormant long enough.

May was blinded at age 31/2 when chemicals he was playing with exploded, destroying his left eye and burning the surface of his right eye, leaving him without sight except for the ability to sense night from day.

Then, on March 6, 2000, he underwent a relatively new procedure in which stem cells were transplanted onto the surface of his right eye in the hope they would replace the scar tissue that made a cornea transplant impossible. May's left eye had suffered too much damage to be repaired.

After the procedure and a cornea transplant, tests showed that May's eye works perfectly. What now fascinates and perplexes researchers is that three years later, May still sees the world largely "like an abstract painting," 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 at San Diego. She and her colleagues leapt at the chance to study May and began testing him just months after his surgery.

"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.

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 done 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.

May's case has also shown that - in what may be surprising to many people - the ability to see can sometimes make life more difficult instead of easier.

When he first attempted to ski with his restored vision, for example, he found it frightening and difficult because the visual images confused and distracted him.

"All of a sudden when I could see all this stuff, my heart was in my mouth. I was falling. I wasn't turning when I was supposed to be turning," May said.

He could only ski with his eyes closed. But since then, he has begun learning how to interpret some of what he is seeing.

May has adjusted well, but he says regaining vision has not changed his life dramatically. Given a choice between seeing and going to the moon, he would opt for a trip into space.

"Lots of people can see and tell you about it. But how many people can tell you that they've been to the moon?" May said.

Still, May said, vision has enhanced his life, too.

"The first time the experience of having vision brought tears to my eyes was in a very unexpected situation. It was at a parade. I was sitting with my boys watching a parade and getting all this visual information and it sort of hit me all at once - this is amazing."

- Information from the Washington Post was used in this report.

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