Eye Teaming

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While eyes are designed to work as a team, each eye functions independently.  When a child looks at something, his or her right eye records the image separately from his or her left eye, which records its own image.  The two images are transmitted up the optic nerves to the brain, which combines them into a single picture.  For the visual system to work correctly, each eye must aim at the exact same point in space so that the images recorded are identical.  This allows the brain to combine, or "fuse" both incoming images for single vision. If the eyes aren't aiming together, the images recorded are slightly different.  If the disparity is great enough, the brain can't combine the two pictures.  The result is double vision.

About 10% of school-aged children have eye teaming problems, technically referred to as convergence insufficiency or convergence excess.  At close up distances required for reading, children with eye teaming problems are only able to aim their eyes together correctly for short periods of time.  As the ability of both eyes to aim and function as a team breaks down, a child’s eyes end up pointing at slightly different places on the page, resulting in visual strain and eventually blurred, scrambled, or double print.  When the strain on his or her eyes is so great, a child with an eye teaming problem can find it difficult to concentrate and remain on task.  This can lead to misdiagnosis of Attention Deficit Disorder (ADD).  Other symptoms of eye teaming problems include loss of place as the print "swims" and moves, fatigue, headaches, and frustration.

To keep from seeing double, a child with eye teaming problems may end up suppressing an eye.  Suppression occurs when the brain "turns off" one eye by neurologically blocking its visual input.  This allows a child to maintain single vision because he or she is only using one eye.  While suppression helps a child cope, it is exhausting and not conducive to concentration.  A child will adapt to seeing this way, and may not recognize that he or she is fighting to maintain a clear, single picture. A child may not realize something is wrong and report transient double vision or the eye-strain and fatigue associated with suppression.

Left undiagnosed and untreated, eye teaming problems can appear to be a learning disability or Dyslexia, which they are not.  However, the symptoms are similar and only a comprehensive eye exam by an eye doctor can determine if a vision problem is the basis of the child's struggle to read.