Pediatric Vision Disorders
Vision and Reading

The following are excerpts from an article on Vision, Learning and Nutrition by Donald J. Getz, OD, FCOVD, FAAO It is reprinted by premission of: www.children_special-needs.org

This article discusses children�s problems with reading, learning, and behavior caused by convergence insufficiency, tracking problems, esophoria, exophoria, and other visual problems.

Vision and Eyesight
Eyesight is simply the ability to see something clearly, the so-called 20/20 eyesight (as measured in a standard eye examination with a Snellen chart). Vision goes beyond eyesight and can best be defined as the understanding of what is seen. Vision involves the ability to take incoming visual information, process that information and obtain meaning from it.

Two general statements can be made about vision. First, vision is learned. A child learns to see just like he learns to walk and talk. When learning to walk and talk, he has the added opportunity of imitating his parents and siblings. In addition, parents can observe their children to determine if walking and talking are developing properly. Vision development, however, generally proceeds without much concerned awareness on the part of parents. Because of these differences in development, no two people see exactly alike.

Vision is learned; therefore vision is trainable. If a child does not possess the necessary visual skills, he can be taught to possess them through the proper vision therapy techniques.

Adequate Vision Is Critical to Learning Since something like 75% to 90% of all a child learns comes to him via the visual pathways, it stands to reason that if there is any interference in those pathways, a child will not develop to his maximum potential.

The Visual Skills Needed for Academic Success

Visual Acuity:
There are many visual skills which are important for academic success. One of the least important skills is termed visual acuity (clarity, sharpness). This is the so-called 20/20, 20/400, etc., eyesight. All that is meant by the notation 20/20 is that a person is capable of seeing clearly at a distance of twenty feet. Unfortunately, how well a child sees at twenty feet has little to do with how his vision functions at the reading and learning distance � approximately eleven to sixteen inches from the face. In fact, it is my opinion that the Snellen eye chart test which measures visual acuity actually does more harm than good. It gives both parents and teachers a false sense of security that vision is normal. There are many other important visual skills that might not be developed even though visual acuity at distance is normal.

Binocular Coordination:
One of the more important visual skills is the ability to coordinate the two eyes together. A child is born with two eyes, but he must learn to team them together. Some children learn to do this properly while others do not. For example, some children develop a problem known as exophoria, which is a tendency for the eyes to deviate in an outward direction. This is not the same as a condition known as exotropia where the eye actually can be seen to be in an outward position.

Adequate Convergence:
During the act of reading, the demand is for the two eyes to turn inward so that they are aimed at the reading task. If the eyes have a tendency to deviate outward, the child must use excess effort and energy to maintain fixation on the reading task. Most studies have shown that the greater the amount of effort involved in reading, the lower will be the comprehension and the lower will be the performance. When reading, the eyes do not move smoothly over a line of print. Rather, they make a series of fixations looking from word to word. When an exophoria exists, each time fixation is broken and moved to the next word, the eyes will tend to deviate outwards and they must be brought back in to regain fixation. Human nature being what it is, the child generally has an avoidance reaction to the reading task. This is compounded by the fact that anything the child doesn�t do well, he would rather not do. This is the child who looks out the window rather than paying visual attention. He is commonly given labels. He is often accused of having a short attention span and not trying. He is told that he would do better if he tried harder, but he has tried harder to no avail. He is often labeled as having dyslexia, minimal brain dysfunction, learning disability, etc. Commonly, he loses his place while reading and/or uses his finger or a marker to maintain his place. While making the eye movements during the act of reading, he might not land on the next word, but rather land a few words further on. Consequently, he commonly omits small words or confuses small words. Often, he just adds a word or two to make the sentence make sense. If the two eyes are pointing at the same point in space, a person will see the fixated object as being single. Double vision or overlapping vision results if the two eyes are not exactly pointing at the same point. Don�t expect a child to tell you that his vision isn�t clear. He has no yardstick of comparison to inform him that his vision differs from the vision of anyone else.

Overlapping Vision