The Ophthalmologist’s Role in Visual Processing and Learning Disabilities
HAROLD P. KOLLER
KENNETH B. GOLDBERG
There has been a growing public interest in recent years regarding the learning difficulties experienced by a significant number of school children as well as adults. Adult attention deficit disorder has become a more popular item for public discussion during the first decade of the twenty-first century.1 These subjects have traditionally been believed by most to be best addressed by schoolteachers and special education professionals. In the early 1930s an enterprising optometrist, A. M. Skeffington, founded the Optometric Extension Program, which claimed to effectively treat children with learning disabilities (LDs) using “Vision Therapy.”2 The idea was to use a variety of orthoptic and occupational therapy techniques to improve fusional amplitudes of the eyes and enhance eye/hand coordination. He believed that, as do present day “behavioral optometrists, the misalignment of the eyes, however small, as well as visual perception deficits, was at the root of an individual’s learning difficulty.3 We now know that the brain is responsible for LDs as well as most eye misalignments.4
In this chapter we will discuss why and how the ophthalmologist should be aware of visual perception science and its effect on learning. Ophthalmologists have been schooled in visual function and ocular pathology. The science of learning disorders, however, has been neglected in the past by ophthalmology, only to be undertaken by organized optometry, but with no value and evidenced-based studies to back up their claims that the eyes are the primary sites of learning difficulties encountered in our schools.5 We will define the major neuropsychologic divisions of learning disorders, suggest the role of ophthalmology in the diagnosis and treatment of these conditions, and provide some background as to effective multidisciplinary remediation of these disorders. Some seemingly unrelated subjects such as pediatric migraine and systemic medical conditions will also be discussed as they relate to learning disorders.
Ophthalmologists should take the leading role in this field as far as making appropriate referrals is concerned because the public believes they are the experts in visual perception as well as visual function and ocular pathology. Ophthalmologists, especially pediatric ophthalmologists, are often the first experts to whom the pediatrician or primary care family doctor will refer such individuals. Ophthalmology has the resources and inter-medical relationships with other medical specialists such as developmental pediatricians, pediatric and adult neurologists, pediatric and adult psychiatrists, geneticists, and neuropsychologists to create a uniform multidisciplinary approach to correctly diagnosing and treating learning disabled children and adults.
The eyes themselves are not the origin of LDs. Total blindness is usually not a handicap to learning in school because blind children often have never had vision but usually have grown up with auditory and tactile skills plus the knowledge of Braille. Blindness and other eye conditions could alter an individual’s ability to perform in the classroom in a manner identical to normally sighted students, but with special accommodations as dictated by federal law such as the Individuals with Disabilities Education Act (IDEA) these students are able to learn effectively despite their handicaps (law described below).
Partial vision loss, monocular or binocular, may have an impact on reading efficiency. Typically this would involve a child’s ability to scan needed material (i.e., classroom chalkboards, reading materials, and motor activities at recess/gym class). Once again, compensatory strategies in the classroom (provided by IDEA) will help minimize difficulties encountered by these children. There are no data to suggest that these children have an increased rate of formal LD.6 Emotional issues can occur for children with monocular vision, especially if the involved eye appears anatomically abnormal (e.g., microphthalmic or with gross media opacification, lid abnormalities, or untreated strabismus) or if they fail to maintain pace with peers in class because of the stated problems (i.e., cannot copy homework quickly off the board, have trouble keeping up in gym class because of inefficient visual scanning).
Environmental factors can help children with these conditions. The home environment (including parental support and understanding), the ability of classroom teachers to comprehend the handicap, and the appropriate prescribing of optical and other visual aids (e.g., large-print books, magnifiers and telescopes, and enhanced video and computer monitors) help these individuals receive information in a more efficient and effective manner. Ophthalmologists need to be actively involved in academic planning for these children given that ocular pathology is the cause of the academic struggles. However, in most cases a significant or serious academic problem does not occur unless there is a comorbid underlying LD caused by brain processing dysfunction. A common example of this would be retinopathy of prematurity, which also results in multiple risk factors for central and peripheral neurologic insult and an associated high degree of LDs, based on low birth weights.7,8 Pediatric ophthalmologists should be aware of IDEA and Americans with Disabilities Act (ADA) plus other state laws showing how they can aid children in the classroom by developing a prescription for academic accommodations. Ophthalmologists can certainly refer these individuals for neuropsychologic testing or to other appropriate professionals in collaboration with their primary care physician.
SYSTEMIC CONDITIONS THAT MAY AFFECT READING AND LEARNING
Many systemic conditions can be responsible for temporary or chronic visual disturbances in the classroom that can impact performance and reading efficiency. Learning in the long term, however, is not affected. Children with chronic allergies that cause tearing, itching, redness, and burning often have these annoying symptoms during class. Appropriate treatment is readily available with antihistaminic eye drops. Other systemic conditions such as juvenile rheumatoid arthritis, chronic sinusitis, and ocular trauma all, at one time or another, can result in some visual discomfort and make reading a bit stressful (usually leading to frustration or reduction in reading rate or fluency). They never interfere with learning or cerebral processing function and can once again be compensated for with accommodations (i.e., increasing time for reading, books on tape, having a “note-taking” service for class).9
Other disorders affecting learning that an ophthalmologist frequently sees include Tourette syndrome and other developmental neurologic conditions (i.e., cerebral palsy). Idiopathic sleep disorders can also affect learning, as can social and family dysfunction or poor school instruction. Several serious genetic diseases are frequently associated with learning disorders. These include familial dysautonomia (Reilly-Day syndrome10) and mitochondrial cytopathy.11 Both of these conditions involve multiple organ systems. The brain is a high oxygen/energy uptake organ system, and the mitochondria are the oxygen generators of our cells. Any disease of the mitochondria affects most organ systems. The autonomic nervous system is almost nonfunctional in familial dysautonomia, and brain processing is also affected. Much more research regarding mitochondrial (not nuclear) inheritance is required to associate learning disorders with these conditions. Familial dysautonomia may also be a partial mitochondrial disorder, as might certain types of learning disorders.
OCULAR CONDITIONS AFFECTING READING
Koller has described a number of purely ophthalmic conditions that at times may affect reading efficiency and attention (Table 1).12 All of them do not, however, permanently influence learning. These conditions include strabismus, amblyopia, nystagmus, pituitary disorders, infections (such as herpes simplex), trauma, and various congenital anomalies of the anterior and posterior ocular segments. Convergence insufficiency exophoria/tropia may cause reading fatigue but never has been shown to cause a learning disorder. The other conditions may make seeing a bit more difficult and create a need for more testing time and/or visual aids, but they do not directly or indirectly affect comprehension and learning. Intermittent blurring can occur with any of these conditions. IDEA and help with Individual Educational Plans are available to such students, if only for the period their ocular symptoms are active. This of course may be permanent in a number of cases (i.e., albinism, optic atrophy). Orthoptic eye exercises may be of benefit for individuals with true convergence insufficiency to alleviate their reading fatigue by creating diplopia awareness and improving convergence amplitudes.
Table 42-1. Visual Perception and Learning Differences in Pediatric Ophthalmology: What the Ophthalmologist Needs to Know About Learning Disabilities in Clinical Practice | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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MIGRAINE
Migraine has been defined as “a familial disorder characterized by recurrent attacks of headache of variable frequency, duration, and intensity, which are usually unilateral and associated with anorexia, nausea, and vomiting, the attacks may be preceded or accompanied by neurological or visual symptoms.”13 The 28th edition of Dorland’s Illustrated Medical Dictionary defines migraine as “an often familial symptom complex of periodic attacks of vascular headache, usually temporal and unilateral in onset, commonly associated with irritability, nausea, vomiting, constipation, or diarrhea, and often photophobia. Attacks are preceded by constriction of the cranial arteries, often with resultant prodromal sensory (especially ocular) symptoms and the spreading depression of Leao; the migraines themselves commence with the vasodilation that follows.”14 Migraines can occur without aura in approximately 10% of the population and are responsible for approximately 60% of all types of migraine attacks.15 Classic migraine begins with an aura, whereas common migraine may not. Migraine may also occur without headache. This “acephalgic migraine” variant is more common in children and may consist of any type of aura16 affecting vision alone (Table 2).
Table 42-2. Visual Phenomena of Migraine | |||||||||||||||||||||||||||||||||||
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Although there are many migraine variants, Dorland’s14 goes on to define acute confusional migraine, which is a rare variant of classic migraine that occurs in children. It is marked by attacks of confusion and disorientation with agitation that manifest as a mixture of apprehension and combativeness. A headache may occur later. We have observed that the cause of frequent complaints of intermittent blurred vision in school-age children while in the classroom, with an otherwise normal eye examination, is migraine. Photophobia is the most common complaint of children who are found to have migraine. In adults, basal migraine is defined as that which results in a prodrome of visual field constriction with various other visual phenomena. In children, this may manifest in the classroom environment as intermittent blurred vision (fortification spectrum). However, on ophthalmologic examination, visual acuity of 20/20 in each eye, near and far, is frequently obtained, with normal stereopsis and no strabismus. They merely are experiencing the pediatric equivalent of adult, constricting visual fields and the typical “scintillating scotoma.”15,17
Pediatric migraine, paramigraine phenomena, and/or associated symptoms in a school-aged child are very important to diagnose early to understand secondary ocular symptoms that might affect classroom efficiency. Migraine is a genetic disorder, and first-line blood relatives will likely have a history of vascular headache syndromes.18 In addition, the affected child will likely have a history of several of the following symptoms19:
Infantile colic
Lactose intolerance requiring a milk substitute
Frequent infantile febrile seizures
Unexplained abdominal discomfort on a recurrent basis
Photophobia
Phonophobia
Hyper smell sense
Allergic predisposition
Sleep disturbances, including nightmares, night terrors, and sleep walking
Motion sickness, especially when riding in a motor vehicle
Type A personality
Macropsia/micropsia/metamorphopsia, in which things seem larger or closer than they actually are, or smaller or further away than they actually are, with and without associated distortion (the “Alice in Wonderland” Syndrome)
Numerous other visual phenomena such as silver foils, sparkling lights, and seeing various colors at different times
These last two symptoms are classified as ophthalmic or ocular migraine (Table 2).20
DIPLOPIA WITHOUT STRABISMUS
Migraine symptoms often go undetected in childhood and may be the only factor responsible for children with visual difficulties in school without other afflictions. Because these children frequently have type A personalities, the fact that they have recurrent disturbing symptoms without an apparent cause may in and itself cause them to have difficulty concentrating in school, the intermittent blurring notwithstanding. The blurring is believed to be a result of vascular constriction causing decreased blood supply to the retina. There are a significant number of children with defined learning disorders who also have migraine or paramigraine symptoms that may interfere with concentration and attention in the classroom and at home (personal observation).21
A comprehensive medical history and appropriate treatment are always indicated in severe cases that involve functional incapacity. The worst cases of migraine in children can involve ophthalmoplegias in which paralysis of one or more of the extraocular muscles cause diplopia. Double vision may last for hours or months and can be disturbing to the school-aged child. Diplopia without strabismus, however, is more frequent.18
LEARNING DISABILITIES
LD can be defined as “a generic term that refers to a heterogeneous group of disorders manifested by significant difficulties in the acquisition and use of listening, speaking, reading, writing, reasoning, or mathematic abilities. These disorders are presumed to be caused by central nervous system dysfunction and may occur in conjunction with other handicapping conditions (e.g., mental retardation, psychologic problems) and environmental circumstances (e.g., poor instruction).”21 LD can take a variety of presentations based on the symptoms that the child demonstrates (i.e., reading disorder, math disorder, disorder of impulse control, and disorder of social cognition) and can be a result of a variety of pathologic causes (i.e., genetic, environmental base).
The literature has reported that approximately 7% to 15% of all school-aged children have been diagnosed with an LD.22 Other samples have varied depending on definitions of LDs and sampling procedures.23,24 There has been much debate as to how to define and quantify LDs to enhance nosologic systems and diagnostic clarification. These diagnostic systems seem to differ between professional groups (i.e., physicians, psychologists, and educators) and jurisdictions (state by state). Several methods of defining LDs include (a) intellectual functioning versus achievement discrepancy; (b) grade level discrepancy; (c) response to intervention; and (d) cognitive processing models.
MODELS OF LEARNING DISABILITIES
The intellectual functioning versus achievement discrepancy model or aptitude versus achievement model is the most commonly used practice in diagnosing LDs in the school setting.25,26 The premise of this model is that the individual’s IQ score should be approximately equivalent with his or her academic achievement. Instances in which the achievement level is below the IQ score, by a certain degree (not defined in strict terms), would lead to the diagnosis of an LD. This model has advantages in that it is the easiest to operationally define and perform in a daily setting. The standards can be held in a rigid fashion by schools and are easy to enforce. However, there are many problems with this model, including the size of the discrepancy that is needed to diagnose LD and psychometric difficulties with testing (i.e., it is difficult to discover LD in younger children in this model because of the test properties and because LD may be more difficult to diagnose in children at the extremes of IQ). Moreover, this approach does not appreciate the aberrant cognitive processes that lead to the diagnosis, which would ultimately aid with the development of remediation strategies.
The second model, less commonly used by schools, is that the child shows a discrepancy from his achievement grade norm. Inherently this model does not account for aptitude and thus would place individuals with low aptitude into LD classifications. This method, rarely used, would change the definitions of mental retardation and would likely not provide adequate programming for individuals with low aptitudes who would not be able to achieve even with specialized instruction in the LD classroom environment with an academic-based curriculum (as opposed to a more functionally based approach training children at low levels in life skills).
A recently proposed model is the response to intervention model.27 This model proposes that children who fail to progress in school, with intensive instruction geared toward individual learning needs, are learning disabled. The problem inherent with this model is the failure-based position of having to watch a child struggle until he or she can receive specialized instruction, possibly taking many years. Shaywitz has reported that early intervention and specialized instruction have led to better functional outcomes.28 This methodology would hamper the child’s access to early interventions.
The cognitive processing model is one put forth by the field of neuropsychology.
Neuropsychology is a branch of psychology that studies the relationship between brain function and behavior.29 Neuropsychology, as a field, attempts to study areas of the brain and correlate certain behaviors (i.e., memory, language, attention/concentration, problem solving, reading, and math) with the underlying physiologic brain region. The neuropsychologic study of LDs operates under the notion that brain systems develop in concert with the environment and stimulation to specialize in the processing of certain types of information. Foder30 called this modularity, and Pennington31 refers to this phenomenon as the genesis for the creation of his model for the study of LDs.
Foder’s (1983) modularity hypothesis also plays a role in the understanding of the development of LDs and the categorization of LD typologies that will be presented in this chapter.30 Cognitive functions exist in a systematic fashion (i.e., language, visual-perceptual) subsumed by regions in the brain that can be impacted during development through genetic, intrauterine, and/or environmental variables. Each type of LD has a certain prevalence in the community (reading disorders and attention deficit/hyperactivity disorder [ADHD] tend to be greater than nonverbal LDs and pervasive developmental disorders) because the brain systems that underlie reading (posterior left hemisphere) and attention (prefrontal cortex) tend to be more susceptible to damage than other brain regions that are involved in the other conditions.31 This model also allows for the study of comorbid disabilities (a frequent occurrence in the LD population) because the cause of the neuropathology may not always be circumscribed to one functional system. Ultimately, these systems would need to interact successfully to produce optimal academic and social performance.
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