Education Network Journal - Vol 1, July 1998
|What You Should Know
About Vision & Learning
By Harlington L. Hanna Jr.
About The Author
This article was written by Dr. Harlington L. Hanna Jr., former professor of Pediatric & Neuro-Optometry, Southern College of Optometry. Dr. Hanna is a board certified Optometric Physician and Attorney practising both Optometry and Law in West Palm Beach, Florida. In addition to his doctorate degrees in Optometry and Law, he holds a masters degree in Educational Psychology. This article is part of a series written and presented by Dr. Hanna in a special course " Vision & Learning" designed for special education teachers and school/educational pychologists.
|PEDIATRIC EYE/VISION CARE
Pediatric eye/vision care requires special examination and treatment techniques. In addition to diseases and disorders of the eye and visual system which primarily affect children, special attention should be paid to the child's developing visual system.
In particular these developing systems and the stress placed upon them by the demands of school work cause tremendous problems with school and academic performance.
It is important that in addition to the examination for eye disease and eye sight as usually performed in a regular eye examination, other systems which control a child's focusing, eye teaming, eye tracking and visual perception be examined. These systems are extremely important to ensure that the child can compete with the demands and the visual stress involved in school work. Children who perform below standard in school many times show remarkable improvement with proper eye/vision care. Many times these children have had eye/vision screenings and regular eye/vision examinations which reveal no eye disease and normal 20/20 sight. They may have been given a clean bill of eye/visual health when in fact they have not been examined for many of the functions which would truly reveal their problem.
It is important to have the eye doctor check your child for proper function in the following six (6) areas:
1. PRIMARY AND SECONDARY EYE HEALTH
eye disease limited to the eye and eye disease caused by other systemic diseases or disorders.
2. REFRACTIVE STATUS
Eyeglass needs and measurement of clarity of sight.
3. ACCOMMODATIVE FUNCTION
focusing problems, particularly the stability, accuracy and ease of focusing.
The teaming of both eyes in maintaining good depth perception and fusion under the stressful situations caused by reading, close work and concentrated school work.
5. OCULAR MOTILITY
The tracking of the eyes particularly in precise demands like reading.
6. VISUAL PERCEPTION
The function that allows the brain to interpret what the eyes see. In children this function is the last to develop fully. All of the physical attributes of vision may be fully functional yet the child may still have problems understanding what he or she sees. Dyslexia is a classic example of a visual perceptual problem.
If your child exhibits any of the following signs or symptoms you should immediately have the child checked by a Pediatric Optometrist:
The most important fact to remember about your child's vision is that the child may have perfect eye health (no eye disease) and perfect clarity of eyesight (20/20) and still have significant vision problems, particularly the kinds of problems that can cause poor school performance.
WHAT YOU SHOULD KNOW ABOUT PROPER EYE EXAMINATIONS AND EYE CARE.
Consumers of health care in general and eye care in particular are increasingly confronted with advertising and gimmickry in the market place. Without an adequate knowledge of the essentials of proper eye care consumers are frequently in the position of the blind leading the blind in their search for proper eye care. It is important that eye care patients recognize that a thorough eye examination is the most important element of their primary level eye care, unfortunately most seem unaware of its importance. Consumers should be well educated about the elements of a thorough eye examination since it provides the basis for all other further care. In the increasing commercialization of health care and eye care in particular it is ironic that patients already visually at risk are bombarded with misinformation and advertising gimmickry which further clouds their ability to understand and see fact from fiction and gimmick from quality.
Patients seeking good eye care should ensure that the eye examination covers the six (6) major areas of ocular and visual function: Eye health, Refractive status, Ocular Motility, Binocularity, Accommodative Function, and Psycho/Perceptual Visual Function.
All areas of evaluation are essential for a proper general eye/vision evaluation of all patients. Unfortunately in practice many times only the first two areas are emphasized. In particular the evaluation of childrens' vision as it pertains to the development of the visual system and school performance requires careful evaluation of the last four areas. Also evaluation of these functions are critical for college students, those who use computers extensively or who other wise do a significant amount of near reading or close work. All of these types of patients may have excellent ocular health and 20/20 sight but may still have significant visual problems which may go undetected if these last four (4) areas of function are not adequately evaluated.
|A thorough eye examination covering these areas
can be obtained from any conscientious eye doctor, Optometrist or
Ophthalmologist, practising primary eye care. Typically in the modern eye
care marketplace most Optometrists specialize in primary eye care & disorders
of the visual system, most Ophthalmologists specialize in eye surgery. Thorough
eye examinations should be regularly performed every year. The following
is a breakdown and brief explanation of the (six) 6 major areas of ocular
and visual function:
1. EYE HEALTH
The examination should cover 3 basic areas.
A. Primary eye disease, such as cataracts and glaucoma where the disease is limited entirely to the eye.
B. Eye disease or function secondary to neurological function. The eye in many aspects is an extension of the brain, and many primary neurological diseases may have one or several eye signs.
C. Eye disease or function secondary to systemic diseases. Many systemic disorders such as diabetes and hypertension may have one or more eye signs. Diabetes for example is the leading cause of blindness in the United States.
2. REFRACTIVE STATE
Examination of this function includes a measurement of visual acuity (ability for clear sight) at near and far distances e.g. 20/20, 20/50, 20/100 etc. This examination also requires measurement of the refractive error of the eye for both near and far distances. The refractive error is basically the correction needed for lenses to improve sight for nearsightedness, farsightedness, astigmatism and presbyopia. This area of testing is emphasized by many patients because it is the portion of the examination primarily responsible for the eyeglass prescription. It is important to note that such a prescription cannot be adequately determined without a thorough examination for eye disease since the refractive error may be intrinsically related to the health of the eye. Patients may have perfect 20/20 sight and still have significant eye disease.
3. OCULAR MOTILITY
The eyes should be examined for their ability to move in the orbits, for restriction of such movements and for accuracy, quickness, smoothness and facility in fixating on a target. Their ability to shift from one target to another and to follow a moving target should also be evaluated. Testing of these functions has significant neurological significance. deficiencies in these functions may cause problems with reading.
Both eyes must be able to work together so that they aim and point at the same target, and function without undue effort to produce one image from the two images derived from both eyes. The convergence system is the primary system responsible for this binocularity of vision. This ability in humans to make one single image from the images from the two eyes is mediated by the brain. Certain interferences with ocular function may make it more difficult and in some cases impossible for the brain to perform this function of producing single vision. Differences of refractive state in the two eyes, functionally crossed or wall eyes, cranial nerve and muscle disorders, muscle tension and visual acuity imbalances between the two eyes may all cause such problems.
These problems may result in patients experiencing double vision, headaches, significant eye strain, use of only one eye, reduced depth perception, difficulty reading, and poor school performance.
Examination of the relationship between the two eyes for any problem which may interfere with the two eyes functioning as a team is therefore extremely important.
5. ACCOMMODATIVE FUNCTION
The eyes should be able to easily focus up close a certain degree or amount and to do so quickly from far to near and near to far. They should both focus at the same rate, do so accurately, and maintain a stable nonfluctuating level of focus or control of the system. This ability to focus or accommodate is the primary function responsible for the clarity of sight at differing distances. An inability to focus or to be able to maintain stable accurate focusing will cause significant blurry vision even though the patient may have no significant refractive error. Also the association and relationship of the accommodative system to the convergence system is of prime importance and needs to be fully evaluated. Evaluation of the ability of the eyes to focus and produce a clear sharp image without undue effort is therefore important to detect and resolve problems with intermittent or constant blurriness, eye strain, difficulty reading and at times poor performance with school work.
6. PSYCHO/PERCEPTUAL VISUAL FUNCTION
This area involves a wide range of potential problems including types of visual disturbances or dysfunction caused by emotional or psychological factors. Problems may also be primarily of a perceptual nature and may result in confusion and misunderstanding of information taken in through an intact and patent physical vision system. The visual perceptual functions allow the brain to interpret what the eyes see. In children these functions are generally the last to fully develop. All of the physical attributes of vision may be fully functional yet the child may still have problems understanding what he or she sees. In some cases Dyslexia is a classic example of a visual perceptual problem. Other visual perceptual problems may cause deficient visual memory, form, size and shape recognition, and visual figure ground. Because such problems may interfere with the learning process these problems are usually first discovered or suspected by astute teachers, special educators, speech therapists, school and educational psychologists or psychologists in the behavioral specialties. Resolution of these problems usually require further evaluation and treatment by optometric specialists with special training in Neuro-Optometry or Behavioral and Developmental Optometry. Many of these problems may also require a multidisciplinary approach utilizing various therapists and educators for adequate resolution.