Getting at the root of reading problems
When children have trouble reading, parents and teachers need to investigate many possible causes. That's because reading difficulty usually stems from a combination of problems, rather than just one.
One potential problem that is sometimes overlooked is the child's vision. This may happen because the child appears to be able to see, does not complain about his or her eyes or has passed a school vision screening.
Reading requires the integration of a number of vision skills: visual acuity, visual fixation, accommodation, binocular fusion, convergence, field of vision, and form perception. The typical school eye chart test only evaluates distance visual acuity. And parents, teachers or children often don't notice the symptoms of reading-related vision problems.
A comprehensive optometric examination, however, covers all of these vision skills. Any child who is having trouble reading should have a comprehensive eye exam. Following are the vision skills that your optometrist will evaluate during the exam:
Visual Acuity. Visual acuity is the ability to see objects clearly. The typical eye chart is designed to be seen at 10-20 feet and measures how well or poorly the child sees at that distance.
Visual Fixation. Fixation is the ability to aim the eyes accurately. Static fixation is the ability to focus on a stationary object when reading a word or working a math problem. Saccadic fixation is the ability to move the eyes quickly and accurately across a page to read a line of print. Pursuit fixation is the ability to follow a moving object with the eyes. These complex operations require split-second timing for the brain to process the information received and to track the path of the moving object.
Accommodation. Accommodation is the ability to adjust the focus of the eyes as the distance between the individual and the object changes. Children frequently use this vision skill in the classroom as they shift their attention (and focus) between their book and the chalkboard for sustained periods of time. Being able to maintain focus at near distances is important for reading, writing and taking tests.
Binocular Fusion. Binocular fusion refers to the brain's ability to gather information received from each eye separately and form a single, unified image. If a child's eyes are not precisely aligned, he or she may experience blurred or double vision, discomfort, confusion or avoidance. If that occurs, the brain often subconsciously suppresses the vision in one eye to avoid confusion. That eye may then develop poorer visual acuity (amblyopia or lazy eye).
Convergence. Convergence is the ability to turn the two eyes toward each other to look at a close object. Children depend on this vision skill for school desk work.
Field of Vision. Field of vision is the wide area over which vision is possible. It is important that a child be aware of objects in the periphery (left and right sides and up and down) as well as in the center of the field of vision. Near central (or para-central) vision is important for reading ability.
Perception. Visual perception is the total process responsible for the reception and understanding of what is seen. Form perception is the ability to organize and recognize visual images as specific shapes. The shapes the child encounters are remembered, defined and recalled when he or she begins developing reading skills.
Treating Reading-Related Vision Problems
During a comprehensive eye examination, the optometrist examines these vision skills and determines how well the child is using them together. If your optometrist diagnoses a vision problem, he or she can prescribe glasses, vision therapy or both.
Vision therapy can be very effective in treating reading-related vision problems. Your optometrist designs an individualized program of training procedures to help your child acquire or sharpen the vision skills necessary for reading.
Because reading problems usually have multiple causes, treatment must often be multidisciplinary. Educators, psychologists, optometrists and other professionals must work together to meet each child's needs.
The optometrist's role is to help the child overcome the vision problems interfering with the ability to read. Once this is accomplished, the child is then more capable of responding to special education efforts aimed at treating the reading problem itself.