Children's and Infant Vision
Introduction
Dr. Brisco specializes in developmental vision and one of her passions is working with children. She works with children of all ages, starting at 6 months. She is a consultant to more than 40 schools and helps children achieve their potential.
There is a strong connection between vision, reading, and learning. Undiagnosed vision problems affect learning. Many learning-related issues have a vision component that can be addressed. While some children need contacts or glasses, many vision problems involve deficits in visual skills. These skills include eye tracking, eye teaming, focusing, visual memory and visual discrimination. These children see with 20/20 vision, but do not have the visual skills necessary to read and comprehend at an age appropriate level. Having your child's vision checked early and often is important, especially in families with a history of eye problems or learning difficulties.
Parents and educators should look for the these symptoms of a vision skills problem:
Back to topDoes Your Child Have a Visually-Related Learning Problem?
If your child has 2 or more of the following symptoms, a Visual Efficiency and/or Visual Perceptual Evaluation is strongly recommended to determine if deficient visual skills are interfering with your child's academic performance.
| Eyes feel tired or uncomfortable when reading or studying? |
| Headaches while reading or studying? |
| Feels sleepy while reading or studying? |
| Difficulty remembering when he/she has read? |
| Loses concentration while studying? |
| Words move, jump, or appear to "swim"? |
| Double vision? |
| Do you feel that your child reads slowly? |
| "Pulling" sensation around eyes while reading? |
| Words blur, or go in and out of focus? |
| Loses place, or jumps over letters or words? |
| Re-reads the same line over and over? |
| Avoids reading? |
| Short attention span while reading compared to other activities? |
| Learns better verbally than visually? (i.e. when read to rather then when reading to himself) |
The Role of Vision in Learning: A Parents' and Educators' Guide
by Dr. Elise Brisco, O.D., F.C.O.V.D.
(as was published in the Journal of the Association of Educational Therapists)
Reading is a highly visual task; therefore, a weakness in the visual system interferes with learning. The ability to correctly input and process visual information is critical for optimal reading because visual input precedes cognitive functioning.
Visual dysfunctions interfere with information processing since the extra effort and attention needed to compensate for a visual problem detracts from that available for cognitive processing. For optimal academic performance, visual functioning needs to be efficient, well integrated, and automatic (requiring little attention).
Approximately 20% of the population have deficient visual skills, yet few are identified because tests to evaluate these skills are not part of the standard eye exam. To identify visual-motor dysfunctions, specialized tests beyond the basic optometric or ophthalmologic exam must be performed. This battery of tests is called a Visual Efficiency Evaluation.
A visual skills deficiency may either be severe enough to interfere with a student's ability to learn to read, or mild enough to allow the student to do well academically by using compensatory strategies, but at the expense of not being able to perform to his or her fullest potential.
I believe that every parent and educator should have a solid understanding of how visual skills are involved in reading, be able to recognize symptoms of visually-related learning problems, and know where to go for treatment if a visual deficit is suspected.
I make these bold statements for two reasons. First, a high percentage of children who are having academic difficulty also have a visual skills dysfunction. Second, since deficits in the visual system interfere with a student's ability to perform to his or her fullest potential, we need to appropriately diagnose and treat these problems. When we have done that, we have served our students in the best way that we can.
The purpose of this article is to convey some of the basics about how vision affects learning, and Vision Therapy that I believe parents and educators should know.
Let's discuss some of the visual skills that are involved in reading.
Back to topOculomotor (Tracking)
Reading begins with input of information through the visual-motor system. At the most basic level, muscles move the eyes across the page to gather words and phrases in correct sequence.
These eye fixations are called saccades, and are a learned skill that becomes more precise as a child develops. A preschool child typically uses head and neck movements, rather than eye movements, to look between different objects. By age four to five, the eyes begin to guide the gross motor system in activities such as catching a ball, and drawing. By age 6 or 7, the child should be able to make reading eye movements without head or body movements.
As fine motor control develops, the number of fixations, and the time required per fixation decreases with age. For example, the average first grader makes 224 eye movements to read 100 words, while the average college student makes only 90 saccades. The number of regressions, or re-reads, also decreases with maturation, but this is also dependent on cognition, and reading skills improvement.
A student with underdeveloped eye movement skills may have difficulty keeping his or her place while reading, read letters or words out of order, or have difficulty adding numbers in columns. His reading speed may be reduced because of slow eye movements and frequent loss of place, or due to a small span of recognition (the width of text that is processed per fixation). Delayed or incorrectly developed eye movement control is called an Oculomotor Dysfunction.
Back to topBinocular Vision (eye teaming)
The right and left eyes must move in perfect synchrony so that the images received by the brain are nearly superimposed. Through a sensory process called fusion, these two images are fused into a three-dimensional image.
Visual confusion, decreased depth perception, or double vision can occur if the eyes are slightly out of alignment, or if one image is less clear than the other. This can give rise to headaches, eyestrain, fatigue, and confusion of what is seen, which makes reading difficult and uncomfortable. Children who have difficulty coordinating their eyes, may also exhibit a head tilt, head turn, or even cover one of their eyes to favor the "better" eye, and to avoid seeing double images.
Different types of Binocular Dysfunctions include strabismus (manifest eye turn), heterophorias (latent eye deviation), and fusional instability.
Back to topAccommodation (focusing)
Another visual-motor skill is accommodation, which is the ability to keep the print clear for a prolonged period, and to change focus quickly from near to far, and vice versa. Accommodative dysfunctions can create symptoms such as intermittent blur while reading, and difficulty copying from the chalkboard. Students who are unable to sustain accommodation may do well on short assignments, but do poorly on longer visual tasks because of eyestrain or blurring of print that increases as the focusing system fatigues. Accommodative Dysfunctions include Accommodative Insufficiency and Accommodative Infacility.
Back to topSymptoms of Visual Deficiencies
Symptoms of incomplete or incorrect development of visual skills include, but are not limited to:
- print that appears to move
- print that goes in and out of focus
- frequent loss of place while reading
- eyestrain, fatigue or headaches associated with reading.
- double vision (constant or intermittent)
- head movement to track words
- squinting, tearing
- rubbing eyes
- reading letters or words out of sequence
- abnormal head tilt or turn, or covering one eye while reading
- poor depth perception
- poor eye-hand coordination while writing or catching a ball
Because visual problems interfere with the process of reading, students must concentrate more on gathering visual information rather than the content of what they are reading. Consequently, reading speed and comprehension are usually adversely affected.
Clinically, many of my patients with visual dysfunctions learn better verbally than visually. This is often reflected in the gap between their verbal and performance scores on the WISC test. As reading demand increases with grade level, symptoms of visual dysfunctions tend to manifest more.
Unfortunately, many teachers, parents, and health care professionals, are unfamiliar with the signs of vision problems that may interfere with learning. Children whose visual dysfunctions manifest as learning difficulties, may be thought of as unmotivated, slow learners, learning disabled, or behavioral problems.
Back to topTreatment of Visual Dysfunctions
Vision Therapy (VT) is the prescribed treatment of visual motor and perceptual dysfunctions which was pioneered by the French surgeon, Javal, in the 1800's. VT is similar to physical therapy, except that we are training fine motor skills and integrating vision with motor.
Since visual-motor and visual perception skills are developed rather than innate, these skills are as trainable and modifiable as learning to move your fingers and hands correctly to play the piano or tennis.
During VT, the therapist sets up activities to remediate and teach the development of individual deficient skills which in turn enhances performance. VT for visual-motor or binocular dysfunctions works on developing control and coordination of fine motor skills of the eyes.
VT is successful in helping patients because of neuroplasticity. New neural circuits are developed in the brain by isolating deficient visual skills and training correct eye movement and coordination. Through practice, these neural circuits are reinforced until the newly learned skills become automatic and are incorporated as "normal" behavior.
Back to topMulti-Disciplinary Intervention
Since reading and learning involve multiple skills and factors, other possible contributors must be considered when evaluating a student who is not performing to his or her potential. Some of the symptoms of visually-related dysfunctions could also result from other types of problems.
A case history for a professional from any discipline should include questions to screen for weaknesses that may require multi-disciplinary intervention. I often see students who also need to consult with an educational therapist, speech and language therapist, occupational therapist, nutritionist, or psychologist. A coordination of efforts is paramount for comprehensive and effective care for the patient.
Back to topHome Vision Screening
Besides a case history that includes symptoms of visual motor deficiencies, the following screening tests can be used to determine if a visual motor problem may exist.
If you suspect a tracking or Oculomotor Dysfunction, ask your child or student to follow a small target, such as a letter on a pencil. Watch his eyes for accurate, equal, and smooth eye movements. If his eyes do not accurately follow the target, cannot follow without moving his head or tongue for kinesthetic reinforcement, or his eyes do not follow as a team, he may have a tracking problem.
If you suspect an eye teaming problem, you can check convergence ability by using the same pencil with letters. Begin with the pencil about 10 inches away, and slowly bring the pencil towards the student's nose. Watch for an equal turning in, or convergence, of the eyes. One eye will turn out when the student has lost convergence. This should not happen further than 3 inches from the student's nose.
You can also do a screening for focusing strength, or accommodative insufficiency by noting when the small letter target becomes blurry while you are doing the above test. The student should be able to keep the letter clear to within 3-4 inches of her nose.
Back to topThe Importance of Screening for Visual Dysfunctions
Students with visually related learning problems often "fall through the cracks". These students usually don't complain about their vision problems because they don't know that their eyes are not working properly: they cannot compare their visual world to anyone else's. Consequently, it is critical for educational therapists, teachers and parents to be able to identify symptoms of possible visual skills dysfunctions.
Correct visual-motor and visual-perceptual skills are critical for optimal academic performance since these activities must occur before cognitive functioning does.
Good vision is fundamental to reading, and reading is essential to learning; therefore, by ensuring that your children or students are free of vision problems, you'll be giving them a better chance to perform to his or her fullest potential.
Back to topHow to find a Developmental Optometrist
The following organizations can refer you to a local Developmental Optometrist:
- College of Optometrists in Vision Development (COVD)
- Optometric Extension Program (OEP)
- Parent Active for Vision Development (PAVE)
- Your local professional optometric society
References
Garzia RP, Sesma MA. Vision and Reading: Neuroanatomy and Electrophysiology. J of Optometric Vision Development, 1993; 24(1):4-51.
Solan, HA. Visual perceptual factors and reading. J Behav Optom, 1990; 1(3):60-64.
Vogel G. Saccadic eye movements: theory, testing & therapy. J of Behavioral Optom, 1995; 6(1):3-12.
Griffin DC, Walton HN, Ives V. Saccades as related to reading disorders. J Learn Disabil, 1974; 7:310-316.
Christenson GN, Griffin, Wesson MD. Optometry's role in reading disabilities: resolving the controversy. J Am Optom Assoc 1990; 61:363-372.
Crick F. The Astonishing Hypothesis, The Scientific Search for the Soul, Scribner 1994; 173.
Back to top