Vision & Learning Center
Vision Therapy & Rehabilitation
Vision Problems
Vision & Learning //
It is estimated that 80% of school learning involves the sense of vision. Studies have shown that a significant portion of students struggling with reading have vision problems. That means that these frustrated children can be helped! A comprehensive evaluation for learning-related vision problems can determine the extent to which vision contributes to academic difficulties.
Knowing the signs and symptoms of learning-related vision problems can keep children from struggling needlessly. Children and adults may complain of headaches in the afternoon, rub their eyes, have blurry vision with extended reading, or experience text that seems to swim or float on the page. They may struggle with copying from the board or may hold reading material unusually close or hunch over their books. They may skip words or lines or use a finger to avoid losing place in text. They may have to read and re-read to understand. Some kids with learning-related vision problems avoid reading or have difficulty paying attention when the task involves near vision work such as reading, homework, or schoolwork. The visual skills needed for reading and learning are discussed below.
Children with undetected vision problems struggle in school needlessly. Their "hidden" vision problems keep them from performing to their potential. Teachers and parents often fail to make the connection between poor reading and children's vision. This stems partly from confusion about the meaning of 20/20, partly from a misconception about what school screenings are designed to assess, and partly from the erroneous assumption that all eye examinations are the same. A vision evaluation for learning-related vision problems will take longer than the 15-30 minutes required for a “typical” eye examination. Testing for learning-related vision problems is more extensive, since the visual skills that impact learning involve much more than clarity of distance sight.
Interdisciplinary Approach //
A successful approach to learning difficulties recognizes the uniqueness of each child and the complexity of the inter-related processes involved in learning. Some children suffer from deficits in phonetic decoding, verbal language, or auditory processing--skills needed to make the connection between a word's written symbols and its appropriate sounds. However, a significant portion of children who are struggling to read are not dyslexic at all. Their phonetic, verbal, and auditory skills are fine. They're intelligent. It's their vision that is interfering with their ability to read. In other cases, vision problems co-exist with various non-visual deficiencies. When multiple factors contribute to learning difficulties, the vision problem may severely limit the child's response to remedial programs and other interventions that involve visual tasks such as reading and writing. Educational efforts are most effective when vision is functioning optimally.
Visual Acuity //
First, children must have crisp, sharp eyesight in order to see the board clearly. School vision screenings routinely check children's sharpness of vision at distance--measured by the 20/20 line on the eye chart--and refer children for glasses if they have blurry far-away vision and can't see the board from the back of the room. Unfortunately, this is all that most school vision screenings are designed to check, and children's vision involves much more. Unfortunately, some eye examinations assess little more than eye health, visual acuity, and the need for glasses to see clearly at a distance. Without additional testing to probe the visual skills described below, eye examinations may miss vision problems that affect reading and learning.
Eye Coordination & Binocularity //
Our eyes are designed to work as a team, but each eye functions independently. When we look at something, the right eye records the image and the left eye records the image. Then the two separate 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 being recorded are identical. This allows the brain to combine, or "fuse", the two incoming images for clear, comfortable single vision. However, if the eyes aren't aiming together, then the images being recorded are slightly different. If the disparity is great enough, the brain can't combine the two pictures. The result is double vision or "smeared" or "wobbly" text.
Unfortunately, about ten percent of school-aged children have eye teaming problems--technically, convergence insufficiency or convergence excess. At the 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 their ability to accurately aim their eyes breaks down, their eyes end up pointing at slightly different places on the page. The result is a great deal of visual strain and eventually blurred, scrambled, or double print. Other symptoms include loss of place as the print "swims" and moves, eyestrain, fatigue, headaches, and frustration. Of course, reading and comprehension become increasingly difficult as the child strains to aim both eyes at the same place to keep the print from blurring, jumping, or splitting apart like this:
A successful approach to learning difficulties recognizes the uniqueness of each child and the complexity of the inter-related processes involved in learning. Some children suffer from deficits in phonetic decoding, verbal language, or auditory processing--skills needed to make the connection between a word's written symbols and its appropriate sounds. However, a significant portion of children who are struggling to read are not dyslexic at all. Their phonetic, verbal, and auditory skills are fine. They're intelligent. It's their vision that is interfering with their ability to read. In other cases, vision problems co-exist with various non-visual deficiencies. When multiple factors contribute to learning difficulties, the vision problem may severely limit the child's response to remedial programs and other interventions that involve visual tasks such as reading and writing. Educational efforts are most effective when vision is functioning optimally.
Eye Focusing / Accommodation //
Our eye focusing system, technically called accommodation, allows us to see clearly, especially up close. Our eyes are designed for distance vision, so when we look at something up close, the natural lens in our eye has to change shape to redirect light rays on the retina for near objects to become clear. A muscle inside the eye modulates the shape of the eye's lens for focusing. At the close ranges required for reading, this is the visual skill needed to maintain clear, sharp images for extended periods of time without discomfort, squinting, or eye rubbing. It also includes the ability to quickly shift focus when looking from near to far, such as when looking from our desk to the board. For children with accommodation problems, print will become progressively blurry as they read for longer periods of time, and their eyes will fatigue from the strain of trying to keep the print clear. Sometimes children with focusing problems will hold their books very closely or adopt an unusual reading posture. Headaches are common. Reading glasses or bifocals are sometimes prescribed for children to compensate for inadequate focusing systems, and sometimes vision therapy is needed to improve a child's focusing accuracy and stamina.
If a child is struggling with his focusing system, print on the page will often look like this:
Eye Tracking / Motility //
Tracking skills, or the ability to control the fine eye movements required to follow a line of print, are especially important in reading. Children with tracking problems will often lose their place, skip or transpose words, and have difficulty comprehending. Many are forced to use their fingers to follow the line because their eyes can't.
When we read, our eyes don’t move smoothly across the line. Instead, our eyes make a series of jumps and pauses as we read. The small jumps between words or groups of words are called saccades. The brief pause we make while looking at the word is called a fixation. After a fixation, we move our eyes to the next word or group of words—another saccade.
This very precise coordination of jumps and pauses is controlled by our central and peripheral visual systems. Our central vision processes what we’re seeing in clear detail and defines what we’re looking at. Our peripheral, or side vision, simultaneously locates surrounding objects and let’s us know where to look. (The parvocellular and magnocellular systems are sometimes referred to as the "What is it?" and "Where is it?" systems.) In reading, our central vision processes the word, while our side vision locates the following word and tells us where to aim our eyes next. The integration of these two systems is what allows us to efficiently move our eyes along a line of print without overshooting or undershooting, or mistakenly aiming our eyes at lines above or below. Without fluid, continuous integration of these two systems, reading is halted or jerky, loss of place in text is common, and comprehension suffers.
Children with tracking problems can't control their eye movements properly at close ranges. The following is an example of how their eyes move during reading:
Reversals ("b and d" "was and saw") //
Reversals of letters, numbers, and words often indicate a visual perceptual problem with laterality and directionality. This involves awareness of the sides of one's body and position in space. While reversals are common in kindergarten, they should disappear by the end of second grade. This is not "dyslexia," but a vision problem. Visual perceptual testing by a developmental pediatric optometrist can determine the presence and extent of this and other visual perceptual problems. Visual perceptual therapy may be prescribed to remediate problems with letter reversals and other deficits.
Visual Motor Integration //
This is use of the visual system to guide movement. Visual skills are important for both sports performance and good handwriting. Twenty percent of the visual data coming from the retina does not go back to the visual cortex for imaging but breaks away and travels to the brain's motor centers to help with balance, coordination, and movement. Think of it as a visual "follow the leader": the eyes go first and tell the muscles where to follow.
Gross Motor Eye-Body Coordination--the efficient visual input to the body's relationship with its surrounding space, commonly referred to as eye-body coordination. Good visual motor and bilateral integration skills allow children to use their visual systems to monitor and adjust placement of their body weight against the gravitational forces on both sides of their body's midline, allowing for good balance and coordination. Children with poor eye-body skills may have difficulty in such areas as sports, learning to ride a bicycle, or general "clumsiness."
Fine Motor Eye-Hand Coordination--the efficient visual input into the body's fine motor system. Children with poor eye-hand coordination may have poor handwriting and take longer to complete written assignments. They usually become frustrated over time and may be self-conscious about the appearance of their writing. Occupational therapy for fine motor skills frequently improves handwriting. When gains are limited, or when writing frequently drifts up or down and away from the line, a vision problem is often present.
Vision Therapy //
There is help for children who struggle to read and learn because of learning-related vision problems. A complete diagnostic work-up determines the extent to which a child's visual skills are hindering school performance. Vision therapy is the science of remediating inadequate visual systems to improve function and performance. It is a form of physical therapy performed under the supervision of a doctor of optometry with postgraduate residency training and certification in the field. Vision therapy is highly successful, supported by decades of research and the testimony of countless parents and children whose lives have been changed when dysfunctional vision systems are restored to normal. Remove a child's stumbling block to learning, and you allow him the opportunity to succeed.
If you suspect your child may be struggling because of an undiagnosed vision problem, you may want to review the checklist of common symptoms. You may also want to attend one of our regularly scheduled public workshops on topics including vision, reading, and A.D.H.D. For more information, contact the Vision & Learning Center of Northcentral PA at (570) 546-4885.