Physical therapy, psychotherapy, occupation therapy, speech and hearing therapy, vision therapy…wait a minute? Vision therapy? Is that a new one? No, it has been the recommended therapeutic treatment for training the visual system to function maximally for over seventy-five years.
Nobody is born with perfect vision-vision is a developmental process. As with all learned behavior, vision is influenced by both heredity and environment. Just as the infant learns to coordinate other body parts to perform activities such as crawling, walking, and talking by interacting with the environment, he must learn to use both eyes as a team-a concept termed “binocular vision”.
The vision system is the human’s most complex sensory system. Consider the fact that the brain has twelve cranial nerves-six of those nerves are solely connected to the eyes, and two have minor connections to the eyes. Considering how much of the brain input is visual in origin, the assumption can be made that vision is the primary sense. It has been estimated that eighty to eighty-five percent of what humans learn enters the brain through the vision system.
The first three years of life are critical to the development of human vision. Vision-It’s Development in Infant and Child by Arnold Lucius Gesell examines the work done in the area by the Gesell Institute for Child Behavior and establishes norms for the different age groups. Various factors can interfere with the normal development of the vision system. Prenatally, fetal oxygen deprivation can have a significant impact. At critical developmental stages after birth, high fevers, trauma, and other environmental factors can adversely affect vision development. These early disruptions can cause amblyopia (lazy eye), strabismus (crossed-or walleye), and/or high refractive errors (extreme nearsightedness, farsightedness, or astigmatism). These conditions are problems in vision development.
Ideally, the two eyes develop the ability to work together as a team-binocular vision-enabling the child to develop basic gross motor skills such as skipping, hopping, jumping, running, throwing, catching, and balancing. Then, in turn, fine motor skills, including hand-eye coordination develops. Any disruption in binocularity interferes with the ability to perform these tasks. This causes developmental delays and failures that may be subtle at first, but become more obvious as the stress level increases because of the complexity of tasks. The child’s performance begins to lag behind that of his peers. This is often evidenced by the inability to attend until completion of tasks, low frustration threshold, and loss of meaning or comprehension. Subjective symptoms may include headache, double vision, and blurred vision. These problems may result in poor academic performance and self esteem issues. The child is often described as lazy, disruptive, immature, or in need of medication. They are also frequently labeled as “learning disabled”. This is the child, who if denied proper intervention, will graduate high school unable to read!!
Reading and writing (literacy) are basic skills that must be mastered to function adequately in our educational system. These are visual tasks! G. N. Getman, OD defined handwriting as “the visual control of direction”. Reading depends on the ability to track, fixate, and focus on printed material. Any interference in binocular function impedes reading ability and comprehension, as well as the ability to write legibly with proper orientation (e.g. b/d and saw/was) and spacing.
To prevent children from experiencing visually related developmental problems, a developmental vision examination should be performed at or before three years of age or even earlier if a problem is suspected, by a person trained in behavioral or developmental vision. Once a problem is identified or diagnosed, the recommended treatment to remediate the problem is vision therapy through the use of lenses and/or vision training by a qualified professional.
Vision therapy arranges conditions so that the brain can receive, process, and respond to visual stimuli appropriately. This involves the use of lenses, which alter visual input. Most children described as having visual processing problems simply have problems with inconsistent visual input. Therapy manipulates the visual input, resulting in the development of binocularity, which achieves the desired goal of improved vision performance.