Did you know that your posture and balance can cause changes in your glasses prescription?
Did you know that soccer players almost always have “good” eyes?
Did you know that as we age and are slowed down by disease and discomfort it causes a change in our glasses prescription? Why is this?
The good news is that it is possible for a neuro-optometrist to have a positive effect on posture, balance, gait and movement through the application of lenses and prisms.
In other words, prisms and lenses can cause a realignment of the body through the re-integration of the neural pathways in the brain. Prisms and lenses are extremely powerful tools that a knowledgeable optometrist, working in the area of neuro optometric rehabilitation, can use to alter the distribution of light entering the eye and passing into the brain. These tools are more widely in use now with our war veterans as well as other patients with acquired brain injury, such as Parkinson’s, MS, stroke patients, and victims of accidents.
Let me acquaint you with a different type of structuring of the visual system than you might be used to. You may possibly have heard, and rightfully so, that the visual system is composed of parts that control focusing near and far, turning the eyes in and out, and moving the eyes from point to point, such as along a line of print. These are considered oculo- motor problems. I will be discussing non oculo-motor problems.
How is this relevant to patients suffering from acquired brain injury such as Parkinson’s? I am going to suggest dividing the visual system up in another way, called FOCAL and AMBIENT.
Basically, the focal system is the central vision and the ambient vision is the peripheral vision. And remember, vision is the result of each individual’s operation of these systems as they occur in the brain, not the eyes. The eyes are only the transmitters of information. The brain organizes the visual information and integrates it with posture, movement, spatial organization, manipulation of the environment, and to its highest degree, perception and thought. That’s right. What we see determines how we think. Like the umpire said, “it ain’t nothing ‘til I call it!”
So let’s move ahead with these two systems. A focal system is for information processing. It is not relevant to motor-sensory. The focal system has no interest in where you are in space. It is considered a FEEDBACK system. First, something is seen. Processing occurs in the brain. Information is being fed back based on what is seen or perceived to have been seen.
The ambient system, on the other hand, is a peripheral visual system that transmits information to the brain based on that received from the body and eyes, as the body moves through space. It is a function of vision relevant to posture and balance and gains information from the kinetic/proprioceptive systems (which gather information from the head, neck, spine, and balls of the feet), and the vestibular system (the ears as they pertain to posture and balance), regarding our motion and where we are in space. These systems process motor-sensory information and act as a FEED FORWARD for balance and posture. It is considered a survival system. It is what the football player uses as he weaves his way down the field. It is what the cave man used as he avoided the saber-tooth tiger lurking in the forest. It is what we use to avoid car accidents. And it doesn’t work well unless both eyes work together. The information that comes in from the ambient (peripheral) system directs where we move next, in our body and our minds.
The sum total of the interaction of the focal and ambient systems is the perceptual/cognitive process, which equates to thinking and moving, that is to say, with vision leading movement. Remember, vision initiates the feed forward process that opens the door to foresee and to react to change, both of body position and thinking. How is this relevant to patients suffering from acquired brain injury such as Parkinson’s?
We will start with the Focal system. You may have seen a Parkinson’s patient leaning forward over a walking aid, looking down, and not moving, or moving very restrictedly. This is known as the Parkinson’s shuffle, and is recognized by neuro- optometrists as OVER-FOCALIZATION. It means that the patient has engaged, and is stuck in, the focal feed back system. He is getting information into his brain about the space in front of him, and nothing more. When the body is stooped forward, the peripheral system shuts down so there is no feed forward (ambient) system working. The Parkinson’s patient steps gingerly forward, or not at all, because he does not have the information coming in relevant to where he is in space. There is no spatial judgment occurring, no ability to avoid, or interact with, what is around him. This over-focalization represents a shut down cognitively. It is called cognitive interference.
Parkinson’s disease is considered part of the group of problems under the umbrella called Post Traumatic Vision Syndrome, PTVS, and affects cognition, memory, attention, concentration, motor performance, speech and language. If there is no feed forward for motor movement, there is a loss of feed forward in the area of speech and language also. This FOCAL BINDING negatively compromises the ability of the Parkinson’s patient to utilize the preconscious relationship between thinking a thought, and speaking it. This freezing causes the inability to RELEASE the thought-language-motor flow. And this can be positively influenced by the proper application of lenses and prisms by an optometrist who is skilled in the area of neuro-optometric rehabilitation.
How does the Parkinson’s patient take advantage of this information? By locating a neuro-optometrist to properly analyze the functioning of the focal and ambient visual systems as they relate to the body’s sensory motor systems. This examination includes detailed medical, social, developmental, neurological and visual histories, with questions regarding balance, posture, movement, and prior rehabilitation. This is followed by a lengthy visual analysis, which explores the limitations of ocular motility, misalignment of the eyes, and the limits of binocularity and depth perception. Posture is constantly being assessed as the clinician continues. Asymmetry is noted between the eyes, as it speaks to the alignment of the body and thereby the ability of the body to move through space. The visual midline of the body is also appraised.
In conclusion, the result of this complex analysis is a prescription for lenses and prisms to improve not only vision, but also balance and posture. Neuro-optometric rehabilitative therapy and light therapy can also be utilized to help re-open neuro pathways and visual fields, and enhance thinking.
Dr. Janet Kohtz practices neuro optometry in Riverside, California. She attended UCLA and graduated from the Los Angeles College of Optometry. She is an associate clinical professor at Western University College of Optometry, a member of the Neuro- Optometric Rehabilitation Association and a Fellow of the College of Optometry of Vision Development.