August 26, 2003.
Health24, Eye & vision.
Mike May's real challenge began when he could finally see again.
A chemical accident left him completely blind at the age of three. In 2000, 43 years after May lost his sight, he had an experimental limbal stem cell transplant in his right eye that restored his vision.
The procedure is a rare one, performed in perhaps 100 people each year in the United States and is not related to retina or optic nerve transplantation.
Sight is not that simple.
Now that May, a California businessman, can see, he has found sight is not that simple. His world consists of abstract shapes and colours, but not three-dimensional shapes. He can't identify his wife from her face alone, nor can he tell the difference between male and female faces most of the time. Facial expressions remain a mystery.
Television images are especially difficult. It's just a lot of images flipping this way and that and it's so fast I can't process it, says May, now 49. To this day I still have a hard time following television.
A rare occurrence.
Restoration of vision after long-term blindness is an extremely rare occurrence and, although research on the subject dates from 1793, little is known about the phenomenon.
May's experience represents an unprecedented opportunity to glean information about how vision works. Findings from the first two-and-a-half years of May's life after his vision was restored are detailed in the Aug. 25 online issue of Nature Neuroscience and in the September print edition.
Prior to May's experience, scientists only knew that people who had been blind for a long time and then had their vision restored had difficulty. They just didn't know why. Using advanced imaging techniques, researchers now have an idea of the effects of long-term blindness on various parts of the brain.
When the brain comes into the equation.
This study brings to the surface the fact that restoration of vision is one thing and how the brain perceives the information is different, says Dr Iqbal Ahmad, an associate professor of ophthalmology at the University of Nebraska Medical Center in Omaha, USA. You might be able to go ahead and restore vision, but if the brain has not been conditioned to make sense of the information coming from the retina, then it will be very difficult for the patient.
Functional magnetic resonance imaging (fMRI) revealed the parts of May's brain normally responsible for processing faces and objects were inactive. When he was shown something moving, however, that part of his brain showed high levels of activity.
The parts of the brain that were connected to the motion-processing areas were fine, but the information that was being sent to areas that process objects and faces wasn't lighting up at all, says study author Ione Fine, who led the project while she was a research scientist at the University of California at San Diego. It's very much a wiring thing. He can see. He can't make sense of it.
Because he had been blinded so early in life, May's brain never had the chance to learn how to see. Infants just out of the womb see poorly, says Dr Ivan Schwab, professor of ophthalmology at the University of California, Davis and a spokesman for the American Academy of Ophthalmology. The brain has to put it together and the early years are very important.
Several years ago, Schwab performed a corneal transplant on a woman with a cloudy cornea who could only see colours. After the procedure, the woman was so disoriented, she wanted her old cornea back. The doctors weren't able to do that but they did, at the woman's request, allow her new cornea to cloud over. She preferred the opaque world over the clear window, Schwab explains.
A champion skier.
May was a champion skier when he was blind (a guide skied in front of him and shouted directions), but he had to close his eyes the first time he skied as a sighted person because the experience was so terrifying.
If something is standing still, it might take me five seconds to figure it out. On skis you don't have five seconds, he says. To May, the chair lift coming up the slope appears as a dark shadow, but so does a person.
May says he's better now at guessing at what he is seeing than he was two years ago. He has also got better and faster at figuring out what something is, largely because he's collected an internal library of information.
I've built up the clues, he says. I've seen lots of stuff and I now know what I missed.
Going on an incredible holiday.
Mike was incredibly functional as a blind person so, for him, getting his sight back was not restoring normal life to him. It was going on this incredible holiday, Fine says. He's a real adventure seeker. He loves going on holiday to exciting places. This time, he went on holiday to the sighted world.
For May, vision has enriched his life, but it hasn't fundamentally changed it. He still reads in Braille, using his eyes only as a last resort. His wife has joked that the best part of the transformation was that her husband would be able to sort the laundry colours.
But May himself points to other extraordinary experiences: Standing on top of a mountain and seeing the panorama of mountain ridges and trees and looking at a leaf under a magnifier. I'm just astounded at all the veins and all of that detail, because you can't feel that, he says. - (HealthDayNews)
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