Monday, June 01, 2009
Visual Processing & "Fixing My Gaze"
Sue Barry's wonderful book Fixing My Gaze is now in stores, and it's a terrific read for all neurophiles, professionals in the neurorehabilitation field, as well as parents, educators, and other professionals working with children.
10% of children have vision problems and in our learning clinic, almost half have some difficulties that are vision-related. But vision problems are grossly under-recognized because conventional eye chart tests assess vision one eye at-a-time and without movement, and children (and even adults) have difficulty putting into words what problems they have with seeing (for more on this check out Check out Chapter 4 in our book The Mislabeled Child).
Dr. Barry had been "cross-eyed" and stereo-blind since early infancy. She had strabismus surgery to correct the alignment, but she still couldn't coordinate both eyes together for depth perception.
Excerpt: "When I looked down at the letters on the page, they didn't stay in one place. This problem grew worse as the print got smaller...When I was learning to read, my right eye saw letters located to the left of the letters I saw with my left eye. I didn't merge images from the two eyes but rapidly alternated between my left- and right-eye views. Although I am not dyslexic, I distinctly remember being in first grade and trying to figure out whether the word I was reading was 'saw' or 'was'." In fact - Dr. Barry's problem is essentially the same as what some dyslexic students experience - the slipping of gaze fixation - so at one minute it looks like saw, the next, was.
Like many with visual processing disorders, Dr. Barry heard the old saw that she was past the critical period for retraining her vision, and that nothing could be done to recover it, but frustrated by increasing vision problems in her 40's, she went to see a behavioral optometrist.
After some prism corrections and dutiful practice with visual therapy, suddenly one day something happened. Looking at the steering wheel of her car she realized it looked as if it were "popped out" from the dashbooard. Her stereoscopic vision was "delightful": "The leaves didn’t just overlap with each other as I used to see them. I could see the SPACE between the leaves. The same is true for twigs on trees, pebbles on the road, stones in a stone wall. Everything has more texture."
At right, a study showing that 'lazy brain' results from lazy eye. When light is shined into the amblyopic eye, much less fMRI signal is detected in the visual cortex.
p.s. We came across a recent review on visual crowding - a common problem for many students (dyslexics, visual problems of many types) in every classroom. It is a bit technical, but helpful to support the need for more spacing of worksheets or test items in the classroom.
NPR: Going Binocular: Susan's First Snowfall
The Different Ways We See pdf