Vision-Related Learning Disabilities and Visual Information Processing
About 80 percent of what a child learns in school comes to them visually. In order for vision to help rather than hinder learning, all three parts of vision (the state, functioning and perception of the eye) must be working properly:
1. The state of the eyes pertains to eye health, visual acuity and refractive errors such as nearsightedness, farsightedness and astigmatism.
2. The functioning of the eyes encompasses focusing, the eyes working in tandem and eye movement. A child with a focusing problem may have difficulty reading the chalkboard because they cannot change focus rapidly from near to far. If the eyes do not function properly as a team they may have eyestrain, double vision, headaches and difficulty sustaining attention. Inability to control eye movements means they will lose their place frequently while reading.
3. Visual perception includes understanding what you see, identifying it, judging its importance and linking it to previously stored information. Eye-hand coordination also has to do with visual perception. Visual perception relates to visual memory, too. This means, for example, recognising words that you have seen previously, and using the eyes and brain to form a mental picture of the words you see.
Symptoms of learning-related vision problems include:
- Blurred vision at any distance.
- Double vision.
- Eyes that are crossed or turned in, or that move independently of each other. (amblyopia and strabismus.)
- Dislike or avoidance of close work.
- Short attention span for the child’s age.
- Turning or tilting the head to use one eye only, or closing or covering one eye.
- Placing the head close to the book or desk when reading or writing.
- Excessive blinking or rubbing the eyes.
- Losing place while reading, or using a finger as a guide.
- Trouble finishing timed written assignments.
- Difficulty remembering what was read.
- Omitting or repeating words, or confusing similar words.
- Persistent reversal of words or letters.
- Difficulty remembering, identifying or reproducing shapes.
- Difficulty with sequential concepts.
- Poor eye-hand coordination.
- Evidence of developmental immaturity.
- Headaches, nausea and dizziness.
- Burning or itchy eyes.
- Colour blindness, especially in situations where learning materials are colour-coded.
Many professionals, including teachers, paediatricians and some eye care practitioners focus only on the first of the three parts of vision — the state of the eyes, specifically refractive errors. If vision is defined as seeing a certain size letter on a chart at a specific distance, your child may have 20/20 eyesight with or without glasses, but poor visual skills. The difference is critical. An eye exam by most eye care professionals and all school vision screenings ignore 9 out of 10 visual abilities necessary for a child to achieve full potential in school. Very few Opticians, Optometrists or eye doctors have the interest or specialised training in detecting and treating these visually related reading problems. Don’t assume that all eye exams are the same.
If vision is defined more broadly as seeing clearly, understanding what you see and processing what you see, some children will be diagnosed with a visual dysfunction that affects how they learn.
Hidden visual difficulties are common. According to the American Optometric Association, almost 1 out of 4 children suffer from inadequate visual abilities. While many of these patients have refractive error (nearsightedness, farsightedness, or astigmatism) commonly treated by glasses or contacts, some have additional problems in the functioning of the vision system that are most appropriately treated with optometric vision therapy. About 40% of all Americans have functional vision deficits. Children with vision disorders rarely complain or tell others, because they don’t even realize they have a problem.
These learning disabilities may extend beyond academic performance to more general problems of social interaction. Often associated with learning disabilities — but not defined as learning disabilities per se — are hyperactivity, inattention, perceptual-coordination problems, hearing problems and motor-skills defects.