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Recovering Vision No Overnight Blessing

Editor's Note: Editor's Note: The following article is reprinted from the Hamilton Spectator, August 29, 2003.

One of the most fascinating things about rare medical conditions is that, rare as they are, there are usually one or two similar cases that have popped up in previous decades or even centuries. Each new such case allows the experts of the time to bring the latest thinking and technology to bear on them, creating new insights, but also usually confirming the wisdom of those who came before.

One of the best examples is of those rare individuals who have regained their sight after being blind, either from birth or from early childhood. A new case like this has just been reported, and it sheds dramatic light on the surprisingly difficult adjustments such patients have to make.

I don't use the phrase "sheds light" lightly; it is a testimony to the fact that we are visual creatures, so much so that we tend to assume that vision follows automatically from a pair of eyes that work. But these cases of the recovery of sight have shown just how wrong that is.

The most celebrated case dates back to 1728. Surgeon William Cheselden removed opaque cataracts from the eyes of a teenage boy. It might come as a surprise to know that the boy was not instantly transformed into a normal seeing person. For many months he had great difficulty realizing that the object he just touched was the same as the object he was now looking at.

For instance, confounded by dog versus cat, he would pick up the cat, feel it, then set it down and stare at it, reportedly saying at one point: "So, puss, I shall know you another time." He was perplexed by the fact that those things he liked best, including people, were not the most beautiful things that he saw. And solid objects were a huge challenge: it took him a long time to realize that the reflecting surfaces of objects, and their shadows, weren't simply surfaces painted differently. Then, when he had finally absorbed that information, he was again troubled by pictures of those objects, because he expected them to be three-dimensional as well, not flat.

This case, and the handful since, have generated more theory than anything else--there's been little of the scientist's preferred currency, objective data.

That is, until now. In last week's issue of the journal Nature Neuroscience, a team in California reported a new case of restored vision, the subject "MM" who had lost his sight at three-and-a-half and had it restored a couple of years ago at age 43. Although he quickly made progress in some areas (for instance, he had no trouble identifying colours), he had problems with other visual challenges that most of us would find routine.

He couldn't identify a line drawing of a cube as a representation of three dimensions; transparency threw him completely, and he had great difficulty telling whether a face was female or male, or whether the face was angry, happy or sad.

That last finding was explored further by imaging MM's brain. The MRI showed that the places in the brain that are usually involved in the recognition and interpretation of faces were silent in MM's brain. His brain did react to faces, but in areas whose activities are usually confined to conventional visual processing. In other words, he was "seeing" faces as objects to be sorted out and identified, not as familiar and significant things which require a higher level of analysis.

The explanation for both his visual abilities and disabilities seems to be that those visual perceptions that are wired into the brain early --like colour and movement --were preserved, but those which would have developed later, like analysis of depth (had he retained his vision in childhood), had been lost.

MM seems to be progressing steadily. He had been an accomplished blind skier, but when he first regained his vision, the sight of hurtling down the ski hill was so frightening that he reverted to closing his eyes. He now skis open-eyed--except on the most challenging slopes.

MM's story is like others from the past: recovering vision is never an overnight blessing, and is never 100 percent positive. As strange as it might seem.

Jay Ingram hosts the Daily Planet program on the Discovery Network.