We introduced a seemingly simple set of VT activities in Part 5 that demonstrated the applicability of a central principle in ecological optics, specifically optic flow. It underlies the problems that many patients we work with in a therapeutic relationship have in managing the complexities of the everyday environment, particularly when in motion. We addressed thumb rotations as an example of seemingly simple procedure with many layers of complexity, indicative of what patients have to contend with in interacting with the ambient optic array, in J.J. Gibson’s terms, as they navigate the environment. Sue Barry and I are in strong agreement that the Brock String is one of the most powerful feedback tools we have for localizing in binocular space, and our colleague, Samantha Slotnick, has introduced a variation of this equally elegant in its simplicity and power.
What I would suggest therefore is to do monocular and binocular (or bi-ocular as the case may be) thumb rotations initially, then introduce Thumb-Pinky Vergence Rock as a way to transfer spatial dimension into the ambient optic array. All you need to do is follow Dr. Slotnick’s video, then follow that with the same sequence as thumb rotations. Now you are trying to maintain spatial localization on either foreground or background of the thumb or pinky as you introduce optic flow. This can be done with the patient lying on her back, seated in a chair, standing, walking, standing on a balance board, or while on a walking rail, depending on whether anti-gravity mechanisms need to be passively supported or actively stimulated.
Helping the patient manage movement is crucial. We do this routinely with Eccentric Circles. It is a very different experience when fusing the targets in a hand-held stationary position, or when doing this while in motion. In this context, Roderic Gillilan, O.D. pioneered Dynamic Adaptive Vision Therapy (DAVT) to treat what he termed the See Sick Syndrome. Several years ago our colleague, Dr. Dan Fortenbacher, did a nice visionhelp blog post on this as related to visual-vestibular integration. In this regard, doing Eccentric Circles while introducing movement in a variety of gazes is very important. Opaque backgrounds are fine for encouraging convergence, but managing the transparent circles is much more indicative of what is done when navigating the environment. Tromboning and circling as conventionally done is lovely, but walking while engaging in this, with the optic flow not only of the surround but the background is an entirely different level of visual-vestibular integration.