By Janet Kohtz, FCOVD, NORA
Do you wonder how a pair of glasses could possibly appear to reverse the devastating effects of Parkinson’s disease? And yet, with a proper prism prescription, balance, posture, gait, and cognition can be dramatically changed.
Let’s talk about what vision is. Light comes into the eyes. The eyes are mere transistors of light, transferring energy to the brain. Vision is generated in the brain and involves the integration of vestibular (information from the ears), proprioception (information coming up from the spinal cord and other senses involving balance), and kinesthetic (information from touch), mixed together with information from the eyes.
Therefore, since this occurs in the brain, we, as neuro optometrists, are measuring the brain’s response to environmental changes in space and time. So, there are both internal and external visual systems functioning in harmony to achieve accurate and effortless balance, walking and visual tracking (as in reading and driving). In other words, there is a feed-back system and a feed-forward system in play. It is a sensory motor loop. All the information coming into the brain is integrated and feeds forward into space setting up how we stoop, drag a foot, hold one shoulder higher and one hip lower, and lean forward, back or sidewise. Spatial processing decisions are made beneath conscious awareness, using peripheral retinal signals, along with other sensory signals. Awareness of external target locations is governed by many internal processes. Some of this “thinking” is conscious (voluntary, or intentional) and some is pre-conscious (we move, determine space, and balance according to habitual, and often skewed information).
Glasses with prisms can be a powerful way to effect change in the spatial world by effecting the integration of all the systems in the brain. When there has been a neurological event in the brain, such as Parkinson’s disease, the eyes, always acting as a window OUT into the space-time relationships of the physical world, as well as a window IN, enable better cognition and ambulation.