The Eyes must work together
By Toni Hager, NDS ©2002

There are three main areas of concerns involving the visual channel. Convergence and tracking, central/near point vision and strabismus.

The eyes must work together in a coordinated manner, referred to a visual pursuit. Each eye is controlled by three (3) sets of two (2) muscles and four (4) cranial nerves. These muscles work by one muscle opposing the pull of its combating buddy. 

They include 
1.) pull the eye upward, 
2.) pull the eye downward, 
3.) pull the eye out—away from the nose, 
4.) pull the eye in toward the nose, 
5.) pull the eye out and up, and 
6.) pull the eye out and down. 

Thus, for one eye to move smoothly, it requires the cooperation and coordination of six muscles all working together. The eyes work as a pair; therefore, require twelve muscles to get along and work as a team.

When one muscle is weak and doesn’t "pull his load" the eyes may move in a jerky motion. This causes the child to frequently lose his or her place while reading. When this happens the child may pause until he finds his place again, (which slows down his reading speed); omit words but continue to read; or substitute his own word and continue reading. Omitting or substituting a word frequently changes the meaning of what is being read, causing comprehension to suffer.

You say, but my child has been to the Ophthalmologist. Most eye exams don’t test convergence, nor do most ophthalmologist treat it. CAN LEARN programs can recommend visual eye exercises and other activities that can eliminate the problem.

Convergence is the ability of the two eyes to work in a synchronously together. We can test for convergence with a pen light directly in front of the eyes one foot away. The light should produce a reflection of itself exactly in the center of both eyes. If the reflection is to the inside of the pupil, the eye is looking outward or divergent strabismus or exotropia. If the reflection is to the outside of the pupil, the eye is looking inward or convergence strabismus or entropia. A strabismus is when the eye turns in either direction and is common among school-age children.

What happened to cause these issues?

At birth, a baby’s eyes aren’t yet able to converge properly. Convergence must develop in vision and does so during the creeping (hands and knees) stage of mobility. Early attempts at convergence are inefficient and are called yolking or accidental convergence. In order for the eyes to learn to converge. The child must fixate on an object at a fixed distance from the eyes. While the child is crawling on their tummy, there is no fixed object for them to see. He can look out at varying distances. If the child misses creeping on his hands and knees and either sits, stands or walk, he again sees at varying distances with no fixed target. Developmentally, only creeping on the hands and knees give the eyes the ever present fixed target they need. Where IS a fixed distance? On the floor!!

Individuals with a strabismus needs to go back to this developmental stage and creep a few minutes every day for a few months to eliminate it.

When the eyes do not converge, each eye may see a separate image, causing double vision or diplopia. It’s like looking at a TV with poor antenna causing a ghost or double image. Double vision confuses the brain. To stop the confusion the child may start squinting. The name for strabismus was "squint" because many children squinted to eliminate double vision. The other way the brain will stop the double vision is by the cortex of the brain suppressing the vision in one eye. If one eye is continually squinted or suppressed it will eventually, because of lack of use, become a weak (lazy) eye which is called amblyopia. This happens in about 5% of all children.

Lens and/or surgery are generally prescribed for strabismus. Neither should be considered until the child has properly completed the creeping stage and until proper eye exercises have been tried for a reasonable period. Surgery for strabismus has a poor success rate even when done early. If the strabotomy has been done follow-up exercises and creeping can help improve the results.

Some learning problems related to strabismus:

• Unable to keep eye contact,

• Skip words or line while reading

• Mix columns in math

Many children have undeveloped macular vision, central field of vision. They see more of what is to the side than directly in front of their face. These are the kids who while looking straight ahead can tell you the color of the car beside yours. They skip words, sentences or even whole paragraphs while reading. They can’t find an item they ‘appear’ to be looking straight at. They dislike activities such as watching TV, reading or any close work or hobbies.

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Visual Processing Chart above adapted from work of Lylle Palmer -
     
click to see larger visual (left box) auditory (right box) version

CAN LEARN uses a variety of specific exercises to improve dysorganization in the visual areas. Only by treating these inefficiencies will the problems disappear thus helping your child overcome his/her learning struggles.

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