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An Ophthalmologist's Approach to Visual Processing/Learning Chapter 11. An Ophthalmologist’s Approach to Visual Processing/Learning Differences 243 11 An Ophthalmologist’s Approach to Visual Processing/Learning Differences Harold Paul Koller, M.D., F.A.A.P., F.A.A.O. In the past, most ophthalmologists read or The first step in educating ophthalmolo- were told that treatment of the disorders gists is to introduce psychiatry, educational affecting children with dyslexia and other and neuropsychology, physical and occupa- learning disabilities fell outside the field of tional therapy, and educational science in all ophthalmology because the brain, and not the its forms relating to learning differences in eyes, is the main organ active in the process children and adults to the ophthalmology of thinking and learning (Hartstein, 1971; community (Koller & Goldberg, 1999). (An Hartstein & Gable, 1984; Miller, 1988). appendix to this chapter outlines briefly what Because dyslexia, for example, implied an an ophthalmologist in general practice should inability to understand the written word, the know about learning disorders.) The second definitive diagnosis and therapy was in the is to make the diagnosis and treatment of hands of the educators and clinical psycholo- children more efficient by developing a sys- gists, not the ophthalmologist. The role of an tem for classifying disorders that is oriented ophthalmologist, thus, was to rule out disease toward ophthalmologists. This chapter as the first step in determining the reason for describes such a classification system for a learning difference before referring the learning disorders. It then goes on to describe child back to the pediatrician or family doc- causes and treatment of medically based oph- tor for further evaluation and referral. thalmic problems affecting learning, as well This limited role for ophthalmologists in as other conditions affecting learning that are treating children with learning disorders is not purely ophthalmic but which ophthalmol- now being displaced by a move toward an ogists can help diagnose (Koller, 1999a). interdisciplinary approach. The ophthalmolo- gist is often the first expert to whom the pedi- AN OPHTHALMOLOGIST’S atrician refers a child suspected of having a CLASSIFICATION APPROACH TO learning disorder. Educating ophthalmolo- LEARNING DISORDERS gists in the medical and nonmedical condi- tions and situations that could affect learning Children with learning disabilities can be in a child or older individual will help ensure classified into two main groups: (1) those that a patient receives appropriate, effective, with purely medically and surgically treated and timely remedial treatment. ophthalmic disorders that temporarily or 244 ICDL Clinical Practice Guidelines chronically affect learning efficiency in focusing structures of the eyeball (globe) school (DSM-IV: Axis III – general medical itself. Refractive status is inherited, with the conditions), and (2) those with conditions not eyeballs of children shaped like the eyeballs of purely ophthalmic that traditionally have fall- their parents. A nearsighted eye (myopia) is en into the243 fields of the cognitive sciences longer, and the light is focused in front of the and education (DSM-IV: Axis I). The second retina. A farsighted (hyperopia) eye is shorter, group of conditions can be subdivided into the and the light is abnormally focused in back of four traditional types of learning differences: the retina, not on it. An astigmatic eye is one in (1) developmental speech and language disor- which the cornea in front or the lens in the ders, (2) nonverbal learning disorders, (3) middle of the eye is misshapen microscopical- attention disorders, and (4) pervasive develop- ly like a lemon or football, more curved in one mental disorders (PDD). Many of these have direction than the other, 90 degrees away. A observable ophthalmologic findings. The blurry image results from all three refractive social reasons for deficient learning in school, abnormalities (Reinecke, 1965). A corrective such as dysfunctional family environment, spectacle lens is necessary to refocus the light poor instruction, foreign first language, and rays coming from the objects observed to cre- severe psychiatric disease are not directly ate a sharp focused image on the retina, which associated with eye abnormalities (DSM-II is then transmitted to the brain so a person can and IV). The next section discusses the causes interpret what is seen clearly. and treatment of disorders within the first Strabismus is the condition of misaligned main group; that is, medical conditions that eyes in which the eyes are not aimed in the temporarily or chronically affect learning. same visual direction. The eyes may be diver- gent (exotropia or walleyes), convergent Ophthalmic Causes of (esotropia or crossed eyes), or vertically apart Learning Difficulties (hypertropia). They also can be cyclotropic, or misaligned around an anterior-posterior axis There are several purely ophthalmic caus- through the pupil, which can cause significant es of temporary or chronic learning difficul- visual confusion and image “tilt” or torsion. ties. Many times these conditions cause Most acquired strabismus can cause double intermittent blurry vision in school and at vision (diplopia), which is most annoying to home, itchy eyes, redness, foreign body sen- school-aged children. Less frequently, the sation, various visual phenomena, double sudden onset of strabismus with diplopia in a vision, tearing, light sensitivity (photopho- school-aged child or younger may be of para- bia), and ocular pain and headache. All of lytic etiology as a result of a virus infection, these symptoms can affect children’s concen- or even a brain tumor. The paralysis in the lat- tration in the classroom and at home and their ter case is due to one of the three cranial ability to learn efficiently (Koller, 1997). The nerves innervating the six extra-ocular mus- main categories of ophthalmic causes affect- cles in each eye being affected. A thorough ing learning are refractive errors, strabismus medical evaluation is mandatory (Parks, and amblyopia, nystagmus, systemic diseases 1975). affecting the eyes, local ocular diseases, and Treatment for exotropia is usually surgi- neuro-ophthalmic disorders. cal, although for small deviations and those Refractive errors are optical refractive less severe cases in which the eyes go out imperfections due to the size and shape of the more at near (convergence insufficiency) than Chapter 11. An Ophthalmologist’s Approach to Visual Processing/Learning Differences 245 in the distance (divergence excess), eye “A” and “V” syndromes in which the eyes go exercises in the form of classic orthoptics or “in” or “out” more in one gaze than in anoth- optometric vision training is quite acceptable. er. For example, a “V”-pattern esotropia is The idea is to train diplopia awareness to one in which the eyes go in more when look- improve fusional convergence amplitudes. ing down than when looking up, which could This enables the individual to see and focus cause double vision when reading. Treatment singly over a broader area of viewing and for a is either with bifocal eyeglasses or surgery if longer duration (Bedrossian, 1969). Treatment spectacles are ineffective. for nonparalytic esotropia (the eyes are Amblyopia is the term applied to dimin- crossed in but move normally in all directions ished vision without an obvious physical or and to the extreme gaze positions) is usually structural abnormality present to account for surgical or optical (eyeglasses) if there is the vision loss (Simon & Calhoun, 1998). It excessive farsightedness. In such a case, the is called “organic amblyopia” when the eyes over-focus and turn in too much. The vision loss is due to a structural defect such hyperopic power of the glasses assumes the as an abnormal optic nerve. The lay term for focusing function and, when the lenses are amblyopia is “lazy eye,” which people often worn, the eyes do not have to focus to see confuse with strabismus or “a weak eye mus- clearly and the eyes remain straight. If the cle.” A more appropriate term for amblyopia eyes turn in more at near than in the distance, would be “lazy vision.” There are three types bifocal eyeglasses are required to cause more of amblyopia: (1) refractive, due to the eyes focusing relaxation close up. There are cases, having different refractive errors and focus- however, involving both esotropia mecha- ing ability; (2) strabismic, in which the eyes nisms that require both glasses and, for the are not aimed at the same object, causing portion of deviation not controlled by the eye- diplopia to occur; and (3) occlusion ambly- glasses alone, surgery. If left untreated, the opia, in which one eye has unclear or opaque weaker eye may develop suppression in order media inhibiting light from being clearly to avoid double vision and become ambly- transmitted from the environment to the reti- opic. Paralytic as well as restrictive esotropia na, such as a cataract. patients often present with face turns to pre- For vision to develop normally, both eyes serve use of their eyes together away from the must be in focus, see clearly, be aligned side of the paralyzed eye muscle. This can straight ahead, and maintain coordinated eye sometimes interfere with efficient reading. movements in all fields of gaze. If this does Treatment is often surgical. not take place, the lateral geniculate body in Hypertropia or vertical strabismus comes the brain develops ganglion cell degeneration in a variety of forms but often it presents to and a subsequent decrease in visual acuity. the pediatrician or ophthalmologist as a head The cause of this in the refractive type is one tilt, chin depression, elevation or face turn, or blurred retinal image in the affected eye and combinations of these abnormal head pos- one clear image in the more normal eye. The tures. These can all interfere with normal brain automatically shuts off the blurry navigation as well as with reading and learn- image and the cells in the lateral geniculate ing.
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