Leuven is a lovely college town in Flanders where history, culture, architecture, gastronomy and modern science merge to form the ideal setting for a workshop on neuropsychology. Were he alive today, Dr. Fred Brock, optometrist extraordinaire, would have devoured the topics presented there. The name Brock is well known in our field primarily because of his contributions to String Theory. Not the same string theory that quantum physics occupies itself with, but the concepts behind an elegant vision therapy tool that serves to elaborate visual space.
The thing about the Brock String when we first demonstrate it to patients is that it looks much too simplistic to be a powerful vision therapy tool. But in the right hands, and with the proper instructional guidelines, it becomes a magnificent tool for exploring one’s visual space world. Here’s the basic idea. Tie one end of a rope to a doorknob and hold the opposite end to the bridge of your nose. Actually, you don’t need me to explain it to you – there’s a marvelous online video that was done that will walk you through it.
The way the video reviews the procedure is the way we routinely instructed patients, largely about the string guiding you on where your eyes are meeting in space compared to where you’re aiming them. We also knew that patients had to be at a certain cognitive level, developmentally, before they were able to deal with it. After all, the normal binocular perception of what we call physiological diplopia is a type of virtual reality experience. Even more, it relies on divided attention to be able to select one bead or point in space and simultaneously be aware of what’s happening in the region in front or behind of that point. This task also requires that the patient attends to the central field while simultaneously being aware of periphery in 3-D space.
But wait, there’s more! Neuropsychology speaks of three regions of space related to your body: personal – in your immediate surround; peripersonal – within reaching distance; and extrapersonal – beyond that point. So with the front bead near your nose, the second bead within arm’s length, and the third bead at the far end, we can depict this as the Brock Graphic Space.
There are all kinds of exciting implications to this. One is that these spatial areas are coded differently by different parts of the brain. Another is that the spatial codes mapping near space and far space are intimately tied in to the accommodative and vergence systems. The notion of personal space may be related directly to the Skeffingtonian “centering” of one’s body in a social setting, a key concept lacking in many children who are on the autistic spectrum. This has further applications to the Brock String regarding the difference in how space is partitioned when one is using, for example a dowel stick to help localize where the middle or far bead is in space relative to the patient’s body.
Now consider this: would the effect of using a dowel stick to localize a point in space by touch be the same as using a laser pointer to localize that location in space? Further, what if an individual were experiencing what is known as visual inattention or neglect after acquired brain injury. Would it be possible to have neglect of one side of visual space selectively in near space but not in far space? The answers to these questions reside in part in what took place in the lovely Belgian town of Leuven, during last weekend’s Neuropsychology Workshop.
Only in part, because it takes a brilliant clinician like Fred Brock to illuminate how we modify these apparent adaptive oddities of visual space. Add lenses, prisms, filters and movement to alter the appearance of the Brock String through the continuum of personal—peripersonal—extrapersonal visual space, and you build a powerful bridge between neuropsychology and optometric vision therapy.
– Leonard J. Press, O.D., FCOVD, FAAO