The initial junction in the brain is a part of the mid brain called the hypothalmus. From these mid brain connections they then split with about 75% of the fibers to continue to the posterior portion of the brain called the occipital cortex. This is where the initial sight process begins to take place, recognizing, shapes, contours, colors, and depth. The remaining 25% then begin to interact to the mid brain functions, such as having effects on the pituitary gland which controls hormone functions.
The retina itself has two specialized neurons to receive light called the rods and cones. Rods are more aware of motion, night vision, the cones are more concentrated in the central retina responding to more sharp critical detail and color recognition.
The most acute area of the eye, is totally concentrated with cones only and is called the fovea centralis while the immediate surrounding area is called the macula lutea.
In measuring the visual field of a person, any obstruction of the pathway to the visual cortex, can show as a loss of visual field. Conditions such as glaucoma, strokes, tumors can then be diagnosed from the visual field evaluation. Rarely do patients have these types of diagnosis. Typically a neurological visual field evaluation will show that all completely normal.
Behavioral Optometrists first and foremost evaluate the health condition of the eye and neurological integrity. Using an example here of a light bulb that is on an adjustable rheostat, it can be made bright to dim. In a dimmer state the light is not broken but it is not giving off as much light as when it is at full brightness. The same can apply to how the eye is able to recieve information.
Utilizing a campimeter, a visual field evaluation can be manually performed. This can measure not only the available level of the visual field but by placing a demand on how the patient is seeing the target, determine the functional use of how much information is being processed. Individuals that present symptoms of information processing, often will be found to have significantly less funtional use of the visual field but the neurological connections are totally normal.
This would be similar to learning problems of a bright person, where there is no known reason why there is a learning problem, when all the evaluations shows as normal. It is not just the amount of available ability but the way in which someone can function with it.
If a deficit is found in this ability, since the eye is only designed to receive light and the brain is doing the processing of what is seen, the use of specific frequencies of light can be applied to the eye to stimulate the retina and expand the functional visual field. This procedure is often referred to as Syntonics.
There are multiple causes of why a visual field may be neurologically normal, but functionally deficient. From birthing difficulties especially forceps delivery, long labor, falls, such as bicycle accidents, sports injury, blows to the head such as from whiplashes, rolling off a baby changing table, high temperatures above 103.5, toxicity, strokes and traumatic brain injuries, even poor nutrition, lighting, emotions and posture can have effects on this.
Many times the exact cause can not be determined but the patient is still deficient in how much funtional use they have of space.
A simple way of measuring the functional visual field, is to stand about arms reach in front of the person covering one of their eyes, and closing one of your eyes so you are both looking at each other eye to eye. Taking your hand and extending it straight out to the side, ask the subject when they first become aware of any of your hand as you move it in from the side holding the palm of your hand parallel to your shoulders and the subject. This should be basically a full arm reach out. Then open your 4 fingers and put them in front of your face. Ask if they can see all four fingers separated. If they can, then covering one eye, again extend your hand out like the first time and ask them when they first become aware of seeing all 4 individual fingers looking straight toward your open eye. If full information and there is no loss of processing skills, it should be close to where they were able to see only your hand. If it is significantly reduced this is an indication that even though all the "WIRING" from the eye to the brain is in tack, their ability to actually use it is reduced.
If it is deficient, have the subject look between your eyes, at the bridge of your nose. Then ask if they can actually see your ears, or is it just a "blob" there, and they know it is a ear or do they actually recognize the ear as an ear. You can then have them stand across the room, and ask them to look at the bridge of your nose, and then ask if they actually see your chest, waist, hands by your side, knees, feet when they are looking straight at your eyes. If this is reduced, these very individuals are often labeled "Klutzy", clumsy, or hyperactive. They will be much more accident prone as the brain is literally not processing the awareness of space, and knowing where they are in relationship to space and time. They often trip over things, and tip over things like a glass of water at the dinner table.
Without the peripheral awareness, they are often touching things to recognize objects, as vision has not evolved to substitute for tactical awareness of information processing. The person will never complain because they are not aware to how the loss of functional vision is effecting them. When touching something, a child will often say very innocently "I was only just looking at it".
An underlying cause for hyperactivity may often be a loss of a functional visual field and the person's only alternative is to revert to the only way of processing information that they have developed. But with touching, they are then scolded as if they have done something wrong and labeled with a multiple terms of various diagnoses ie: Dyslexia ADD, ADHD. They are then medicated and placed in special school programs and the actual hidden problem is never addressed.
If you were to walk into a class room, and look around at the students, you often would notice many students were touching various things. Once touched they then move their bodies to actually look at the object. Another person could walk in and just look around. If the second person had a good visual system, they would have actually visually "touched" more things as the information was processed by the visual system and not the tactical or motor system.
Behavioral Optometrists do not treat the learning problems but the visual dysfunctions that may be associated with learning. Their post graduate training and education is to enable patients to restore the skills necessary to allow increased levels to process information. This in turn may reduce the syndrome of learning difficulties that were caused by an inefficient visual system to process information.
From here tutoring can begin, but should at first be slow and not overload the visual system. Immediately after therapy, it is more balanced but like wet concrete, overdoing things or trying to catch up on homework or other aspects is very much like pouring concrete, and then walking on it when it is still not dry. It will normally take about three months to integrate the new skills of visual processing once released from therapy to begin to restore the lost educational opportunities. At that point the additional intervention such as tutors would be totally appropriate to catch up on what has been missed academically. The visual system must be ready for the demands, before visual learning can take place efficiently.