Agnes M.F. Wong is a pediatric ophthalmologist in Canada who is at the forefront of a revolution in medical thinking about amblyopia. This is significant because, as she notes in her most recent paper, amblyopia is the number one cause of monocular visual impairment worldwide. I think that bears repeating: AMBLYOPIA IS THE NUMBER ONE CAUSE OF MONOCULAR VISUAL IMPAIRMENT WORLDWIDE. While the public health spotlight is on visual impairment as loss of visual acuity, or in low vision circles also defined by the extent of loss of peripheral vision, her co-authored chapter in a book we’ve been highlighting recently on Plasticity in Sensory Systems hammers home the point that the implications of amblyopia are well beyond the Snellen Chart. Here is an example of a recent paper by the Wong group which address visuomotor behavior in amblyopia. I have to confess that I’m not a big fan of the word plasticity to describe the modifiability of the visual system. Seems to me a better term to depict what we’re talking about is elasticity, or stretching the limits of change. Plastic in terms of a polymer still conveys rigidity. I much prefer neuro-elasticity.
Having said that, I want to return to the chapter by Dr. Wong and her colleagues in the book on Plasticity in Sensory Systems entitled Deficits and Adaptation of Eye-Hand Coordination During Visually Guided Reaching Movements in People with Amblyopia. They write the following (p. 64):
“Interestingly, the extended planning interval was also evident during fellow eye and binocular viewing in patients with severe amblyopia. This finding might be surprising at first glance because the fellow eye had acuity of at least 20/20. However, despite normal visual acuity, higher-order deficits in the fellow eye have been well documented in people with amblyopia. It has been hypothesized that higher order deficits exist because second-order neurons are binocular and require normal binocular input during development. Thus, anomalous binocular vision during early development leads to higher-order visual deficits, which can be detected during viewing with either the amblyopic eye or the fellow eye.”
The work by Dr. Wong and colleagues in Canada should broaden awareness in Ophthalmology, and capture more interest on the part of many in Optometry, on treating amblyopia beyond penalizing the better eye which is – as she notes – already compromised in some of its higher order functions. It’s as basic as this: Why punish the good kid in class for the poor behavior of another child? The good kid already has his learning compromised by the attention diverted to the bad kid, so figure out a better paradigm for learning. It’s high time to move beyond patching, and high time to work on motor and cognitive function if we want to treat the whole person in amblyopia rather focus on the central visual acuity of one eye.
Winds of change are in the air in Canada. Beyond the work of Wong and colleagues there is the marvelous research by Robert Hess and colleagues at McGill. He has a chapter in this book as well, and you can read about his prodigious production in visual elasticity, er … plasticity here.