Mike May holds the world speed record for downhill skiing by a blind person. In his competitive days he would slalom down the steepest black-diamond slopes at 65 miles an hour, with a guide 10 feet ahead to shout "left" and "right." The directions were just obvious cues. The rest came from the feel of the wind racing against his cheeks and the sound of the guide's skis snicking over the snow. But May's days as a world-class blind athlete are behind him. He's no longer blind.

May lost his vision at the age of 3, when a jar of fuel for a miner's lantern exploded in his face. It destroyed his left eye and scarred the cornea of his right, but over the next 43 years he never let those disabilities slow him down. He played flag football in elementary school, soccer in college, and nearly any activity that didn't involve projectiles as an adult. He earned a master's degree in international affairs from Johns Hopkins, took a job with the CIA, and became the president and CEO of the Sendero Group, a company that makes talking Global Positioning Systems for the blind. Along the way, he found time to help develop the first laser turntable, marry, have two children, and buy a house in Davis, California. "Someone once asked me if I could have vision or fly to the moon, what would I choose," he once wrote. "No question— I would fly to the moon. Lots of people have sight, few have gone to the moon."

Then one November day in 1999, he came back to his senses. At St. Mary's Hospital in San Francisco, surgeon Daniel Goodman dropped a doughnut of corneal stem cells onto May's right eye (his left was too severely damaged to be repaired). The cells replaced scar tissue and rebuilt the ocular surface, preparing the eye for a corneal transplant. On March 7, 2000, when the wraps were removed, May got his first look at his wife, his children, and for the first time since he was a toddler, himself.

Sight restoration is a periodic miracle— both for its recipients and for the scientists who have the privilege of studying them. As early as the fifth century B.C., Egyptian surgeons used a needle to push their patients' cataract-covered lenses away from their pupils, affording them some degree of sight. More recently, in the late 1960s, surgeons learned to remove cataracts with ultrasound. The stem-cell surgery performed on May was developed in Japan and introduced in 1999. Since then hundreds of people have benefited from it. But of all those who have had their sight restored throughout history, only about 20 recorded cases were blind since childhood, and of those, most had less-than-perfect corneas after surgery. When Goodman peered into May's eye after the surgery, he saw a lens that ought to provide crystal-clear vision.

It doesn't— far from it. Pristine as his optical hardware is, May's brain has never been programmed to process the visual information it receives. May still travels with his dog, Josh, or taps the sidewalk with a cane, and refers to himself as "a blind man with vision." And that paradox fascinates Don MacLeod and Ione Fine, experimental psychologists at the University of California at San Diego. The speed with which babies learn to understand the world suggests that they're born with the ability to process some aspects of vision. But which aspects, exactly? What is learned and what is hardwired? During the past year and a half, Fine and MacLeod have put May through a battery of physical and psychological tests, including functional magnetic resonance imaging, or fMRI, which tracks blood flow in the brain. The results are opening the first clear view into how we learn to see.

Functional magnetic resonance imaging,
here being performed on graduate student
Melissa Sáenz,
tracks blood flow in the brain. UCSD
researchers used this same
technique at Stanford University, in
collaboration with the Salk
Institute, to chart Mike May's visua
processing after his sight was restored.

MacLeod's laboratory at the university is a labyrinth of filing cabinets, optical equipment, and oddly placed desks. "It's well booby-trapped," he says, steering May toward the first of many tests one afternoon. "But May has an uncanny ability to navigate complicated arrangements." Tall and athletic, with features that look boyishly handsome despite his graying black hair, May would make a good James Bond if not for a few side effects of his blindness. Unlike the rest of his body, his eyelids haven't had a lifelong workout. Perpetually half closed, they lend a stoic blankness to his face that's relieved only by the occasional smile. He has yet to learn facial expressions.


Sitting obligingly in front of an ancient computer monitor, May watches as thick black-and-orange bars appear on the screen. MacLeod and Fine are testing his ability to see detail. His job is to adjust the contrast with a trackball until he can just see the bars. A click on a mouse brings up another set of bars, thinner than the last, and he plays around with those until he can see them too. Although his right eye ought to provide 20/20 vision, in reality it's closer to 20/500. Instead of discerning the letter E on an eye chart from 25 feet, May can see it only from two. In the past the blurred vision of people with restored sight was blamed on scar tissue from surgery. But stem-cell surgery leaves no scars. The signals are reaching May's brain, but they are not being interpreted very well.



More than 300 years ago, in a famous letter to the philosopher John Locke, the Irish thinker William Molyneux anticipated what May sees. A blind man who is suddenly given vision, Molyneux suggested, wouldn't be able to tell the difference between a cube and a sphere. Sight is one kind of perception and touch another; they can be linked only through experience.


The most dramatic proof of this theory came in an experiment published in 1963 by Richard Held and Alan Hein, who were then professors at Brandeis University in Waltham, Massachusetts. Held and Hein raised two kittens in total darkness. But every so often they would place the kittens in separate baskets, suspend the baskets from a single circular track, and turn on the lights. Both baskets hung just above the floor, but one had holes for the kitten's legs to poke through; the other did not. The free-limbed cat ran in circles on the floor, pulling the other basket along behind it; the other kitten had no choice but to sit and watch. While the active kitten learned to see normally, the passive kitten stayed effectively blind: Its eyes could see, but its brain never learned to interpret the sensory input.


Held and Hein's experiment has never been duplicated. But in the past half century, studies of sight restoration, most notably by Oliver Sacks and Richard Gregory, have verified that some things can't be understood without experience. Objects, faces, depth— just about everything that helps us function in the world— are meaningless when a person who has never seen before gets sight. "Babies are born into a bright, buzzing confusion, but we can't ask them what it's like," Fine says. "In some ways talking to Mike May is like getting to talk to a 7-month-old."