The right focus

Through vision work,a neurobiologist retrains the adult brain

In the early 1960s,when Susan Barry was in the third grade,the assistant principal showed up one morning to demote her from the class for above-average students to the special-problems class. A boy was assigned to drag Barrys desk behind her down the hall,and the scraping sound it made on the floor would haunt her for years.

Since infancy,Barry had suffered from a vision problem that affects millions of children but is still profoundly misunderstood by science. Barry developed a condition called strabismus,a misalignment of the eyes that causes a variety of conditions; in Barrys case,cross-eyes. Three surgeries as a child made her eyes appear straight,but they still were poorly aligned and sent such confusing signals to her brain that she experienced double vision and difficulty reading.

Barry compensated like those with similar vision problems. Her brain suppressed the image from one eye so she could learn to read. But she could barely see things at a distance. As a result,her brain could not compare the images from both eyes,which would create the perception of depth. Thus,she lacked the stereo vision of normal sight. To judge distances,Barry used other senses or cues,such as placing her hands in front of her or counting steps. Her world was jittery and flat.

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Doctors told her this condition could never be changed because she had passed the crucial period of early childhood,after which the brain becomes fixed and cannot be rewired to read correct signals from the eyes.

But now,in a development that could affect such areas as learning disabilities and soldiers returning from war with traumatic brain injuries,Barry has proved that the adult brain is considerably more flexible than originally thought.

In Fixing My Gaze: A Scientists Journey Into Seeing in Three Dimensions,Barry describes how,at 48,she began vision therapy that accomplished what the best scientists of her generation said could never be achieveda brain that can read eye signals properly and allow sight in three dimensions.

The majority of ophthalmologists still tell parents that there is nothing they can do for their child after the age of 7 or 8, says Barry,now a professor of neurobiology at Mount Holyoke College in Massachusetts,US. Well,I was 48 when the right developmental optometrist taught me how to retrain my brain.

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Barrys vision breakthrough began seven years ago. She sought the help of a developmental optometrist who prescribed a rigorous program of vision therapy. This therapy involved small wooden balls suspended on strings,looking at complicated eye charts through prisms and waving moving objects in her peripheral vision while jumping on a trampoline. All of this was designed to focus both eyes at once on the same object so the brain was receiving accurate,stereoscopic information.

One day,Barry was starting her car when she glanced at the steering wheel and,suddenly,it was floating in its own space,with a palpable volume of empty space between the wheel and the dashboard. For the first time,Barry realised,she was seeing with normal,three-dimensional vision because her brain had been retrained.

With a few more years of intensive training,Barry was seeing normally,and a whole new world of distance vision,trees with normal dimensions and roads she could easily follow,opened up to her.