Do You See What I See? A Scientist's Journey Into 3-D

When Sue Barry used to see snow falling, it would appear as if the snow were falling in one flat sheet in front of her.

"I did not feel like I was part of the snowfall but I was looking in on the snowfall," she tells Fresh Air's Terry Gross.

Barry, a neurobiologist, had been cross-eyed since early infancy. Though she had operations as a young child to correct her eyes' appearance, they still sent conflicting messages to her brain. As a result, she viewed the world in a flat plane and had no stereoscopic 3-D vision.

In her mid-40s, Barry met the neurologist Oliver Sacks at a dinner party. She told him that she didn't think she was missing much by not seeing the world in 3-D. But several years later, after experiencing several side effects from her vision problems, Barry decided to visit a developmental optometrist, who helped her relearn how to view the world stereoscopically.

The result, explains Barry, was breathtaking. For the first time in her life, she was able to see snow falling in the distance in front of her, cascading leaves on tree branches and the shapes of flowers in a vase.

Barry's memoir, Fixing My Gaze, details the way her vision and her way of perceiving the world changed following her intensive therapy sessions. She says that she still stops and enjoys the new way the world looks to her.

"The sense of immersion in a 3-D world is very dramatic and very different from the way that I used to see," she says. "

Interview Highlights

On how the world looked before Barry saw in 3-D

"Space was very contracted and compacted. So if I looked at a tree, the leaves or the branches would appear to overlap one in front of another. But I didn't actually see the pockets of space between the actual branches. So the world was actually smaller and more contracted before my vision changed."

On how eyes produce stereoscopic vision

"The key to stereoscopic vision is the two eyes have to be aimed at the same place in space at the same time. When that happens, the brain can integrate the information coming from the two eyes. I was cross-eyed since the very first months of life -- which means that if I were to look at you, Terry, I would be looking at you with one eye, and the other eye was turned in. And so the two eyes were not aimed at the same place in space at the same time and the brain could then not integrate the information from the two eyes."

On retraining her eyes to see in 3-D

"I went for vision therapy -- not to gain stereo vision. I am a neurobiology professor; I taught for years in the classroom about the concept of the critical period -- that stereo vision had to develop in early life or it was not possible to gain it in adulthood.

"When I went to see a developmental optometrist, what my major complaint was ... when I looked in the distance, everything seemed to jitter. I couldn't drive and read road signs at the same time. Even in the classroom, I wouldn't look at students in the back of the class because to look, especially in a large classroom, took a great deal of effort. Even though the vision in my two eyes with glasses was 20/20. Because of the conflict between the two eyes, it was difficult to see in the distance. ... So my major goal was to find a way to see more comfortably ... I did not expect that I would be able to gain stereo vision. I was quite convinced of the opposite: that stereo vision was well beyond me."

On trees

"I sometimes find myself just admiring the pockets of space between the different branches in a tree and walking and immersing myself in those pockets of space. It is just beautiful. It is a beautiful sensation."