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Retinal Degeneration

DESCRIPTION: Retinal tissue may degenerate for a number of reasons. Among them are: artery or vein occlusion, diabetic retinopathy, R.L.F./R.O.P. or disease (usually hereditary). Retinitis pigmentosa, retinoschisis, lattic degeneration, and macular degeneration are characterized by progressive types of retinal degeneration.

(see also Macular Degeneration and Retinitis Pigmentosa)

TREATMENT: Varies, according to cause, symptoms, or effects. Adaptations in the learning environment may include a variety of optical aids and controlled illumination (especially for glare).

Genetic counseling may be indicated.

IMPLICATIONS: Schoolchildren with diagnoses of retinal degeneration disorders should be under regular and routine ophthalmological care, since retinal detachments are possible.

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Albinism

DESCRIPTION: A hereditary deficiency of pigmentation, which may involve the entire body (complete albinism) or a part of the body (incomplete albinism); believed to be caused by an enzyme deficiency involving the metabolism of melanin during prenatal development; inherited as an autosomal dominant or recessive trait; in the X-linked type, ocular albinism is only visible ophthalmologically in the female carrier; in complete albinism, there is usually lack of pigmentation in skin and hair, as well as in retinal & iris tissue; in incomplete albinism, skin and hair may vary from pale to normal; in ocular albinism, function may vary from normal to impaired. Impairments may involve the retina (especially the macula) and iris; photophobia, nystagmus, and refractive errors are typical. If acuity is decreased, it commonly ranges between 20/70 and 20/200. Visual fields are variable; color vision is usually normal. Prognosis: non-progressive.

TREATMENT: Optical correction of refractive errors; tinted or pinhole contact lenses; absorptive lenses; optical aids, lowered illumination if needed; genetic counseling recommended.

IMPLICATIONS: Adjust illumination to conditions and individual (i.e., control glare via seating and/or tinted lenses; use sunglasses and/or hat with visor outdoors). Classroom seating should be appropriate to the corrected refractive error and photophobia. Should be evaluated for low vision aids. Genetic implications should be noted.

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Amblyopia

DESCRIPTION: (also known as "amblyopia ex anopsia," which is dimness of vision from disuse.) In the absence of organic eye disease, reduced visual acuity in one eye (uncorrectable with lenses) due to cortical suppression; commonly caused by strabismus or by unequal refractive errors, but may also be caused by opacities of the lens or cornea. In strabismus, the image from the deviating eye is suppressed; fusion is lost, as is depth perception. If treatment is not instituted early, vision fails to develop in the deviating eye, and cannot be regained. In older children (over about 8 years of age), amblyopia may be untreatable.

(see also Strabismus)

TREATMENT: Optical correction of refractive errors; occlusion ("patching") and/or orthoptics (eye exercises); surgery to straighten eyes. (Peak age for strabismus surgery success is age 2. Chances for improvement of acuity decrease until approximately age 8, after which acuity improvement is unlikely.)

IMPLICATIONS: EARLY DETECTION AND TREATMENT IS ESSENTIAL if acuity is to be developed and maintained. Lighting according to individual needs. If amplyopia is untreatable (as in an older child), classroom seating should favor the functional eye.

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Aniridia

DESCRIPTION: Rare, congenital absence or partial absence of the iris; genetically caused by an autosomal dominant or recessive hereditary pattern. Often, the iris is vestigal (little more than a margin is present) and the eye appears to have no color (only a larger than normal pupil). Other deformities of the anterior chamber are also often present (e.g., cataract), and glaucoma frequently develops before adolescence. There is usually decreased acuity (circa 20/200), photophobia, possible nystagmus, cataracts, displaced lens, and underdeveloped retina; visual fields are usually normal, unless glaucoma develops.

TREATMENT: Pinhole contact lenses; tinted lenses and/or sunglasses; corrections for refractive errors; optical aids; lower illumination levels to control glare. If glaucoma develops (and regular monitoring for this is essential), medical and/or surgical treatment (i.e., goniotomy or trabeculotomy) may help, but long-term prognosis is poor.

IMPLICATIONS: Control glare through lenses or illumination level. Magnification may be helpful.

Genetic counseling is indicated.

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Aphakia

DESCRIPTION: Absence of the lens, due to surgical removal, perforating wound or ulcer, or congenital anomaly; causes a loss of accommodation, hyperopia, and a deep anterior chamber. Complications include detachment of the vitreous or retina, and glaucoma.

TREATMENT: Strong convex lens prescription, in glasses or possibly contact lenses.

IMPLICATIONS: Good illumination, but avoid glare and excessive light; seating away from windows; good contrast in printed materials.

There is currently some controversy over the use of "black light" with aphakic children. Ultra-violet light is thought to be absorbed by the lens, thus protecting the retina from exposure. When there is no lens to perform this function, the retina is exposed and may be damaged. Precautionary measures suggest that the use of "black light" with any child should be limited, and that care should be taken to shield the light source from the eyes (i.e., do not allow the child to look directly into the light source).

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Refractive Errors

DESCRIPTION: In a normal eye, parallel rays of light focus exactly on the fovea (the central area of the macula), when the eye is in a state of rest (i.e., the lens does not have to accommodate). In a farsighted (hyperopic) eye, under the same conditions, the eyeball is too short, and the light rays focus (theoretically) behind the fovea. In a nearsighted (myopic) eye, under the at-rest conditions, the eyeball is too long, and the light rays come to a focus before they reach the fovea. Astigmatism is an irregular curvature of the cornea in one or more of its meridians. The lens may also contribute to astigmatism (as in old age, when it may become somewhat irregular in shape because of cataractous changes). Astigmatism may be simple(i.e., not combined with hyperopia or myopia), or compound; when an eye has both myopia and astigmatism or hyperopia and astigmatism, it is a compound defect. Astigmatism may also be "mixed" (when myopia is combined with hyperopic astigmatism, or when hyperopia is combined with myopic astigmatism). In middle age (beginning anytime past age 40), the lens becomes less flexible and less able to accommodate for nearpoint viewing; this condition is called "presbyopia" and is described as "when arms aren't long enough." In addition to simple myopia or hyperopia and the variations of astigmatism, and because the human organism has two eyes which must have coordinated visual reception for good vision to occur, a multitude of refractive variations are possible. Anisometropia refers to different refractive errors in each eye, and aniseikonia denotes a difference in the image size in the two eyes.

Refractive errors tend to be inherited, but there is no pattern of inheritance. Size of the eyeball, shape of the cornea, shape of the lens, and depth of the anterior chamber are all variables in refractive errors. These variables increase the possible ocular combinations for refractive errors.

Symptoms of myopia include squinting and frowning; hyperopia may cause a lack of interest in reading, rubbing of the eyes, or even headache, dizziness, or nausea. Astigmatism may cause visual fatigue, headaches, frowning, and squinting.

Degenerative myopia (sometimes also called progressive myopia) is similar to simple myopia except that the degenerative changes occur in the optic disk, choroid and retina, sclera, and vitreous, and are not related to the degree of myopia (i.e., the myopia does not increase; the structure of eye parts changes in such a way that visual function is negatively affected). Loss of central vision, retinal detachment, and vitreous opacities are typical; cataracts and secondary glaucoma may be additional complications. Progressive myopia is genetically determined as a recessive trait.

TREATMENT: Myopia and hyperopia are treated by the use of spherical concave and convex lenses, respectively. Astigmatic corrections are cylindrical and are added to any prescription for myopia or hyperopia. Presbyopia necessitates the use of bifocals or trifocals. In the absence of disease or other ocular abnormalities, glasses or contact lenses are the only treatment needed for refractive errors.

IMPLICATIONS: The wearing of glasses does not "strengthen" or "weaken" eyes, or affect the degree and progress of myopia. Eye exercises are of no benefit in improving refractive errors, since they cannot alter the size of the eyeball or the refractive power of the lens.

Current interest in radial keratotomy (the surgical changing of the shape of the cornea) suggests possible "cures" for high myopia and astigmatism, but the surgical techniques are still in experimental stages. Long-term effects have yet to be observed, analyzed, and documented.

Contact lenses have revolutionized the corrective lens industry, however, both hard and soft contact lenses continue to be somewhat controversial. As with surgical solutions to refractive errors, there are precautions and problems yet to be solved. Contact lenses are preferable to glasses in some kinds of corneal anomalies and in unilateral aphakia, but their general use still assumes user integrity. Severe ocular injury can occur if contact lenses are used carelessly. Moreover, certain occupations (e.g., beauticians) should avoid the use of the soft lenses, since they tend to absorb chemicals that could be harmful to the eye. The decision to wear contact lenses must be made with care; they are not "for everybody."

About 80% of children are hyperopic at birth because of the shortness of the eye; approximately 5% are myopic. During the years between ages 2 and 25, there is a gradual decrease in hyperopia; myopia usually increases somewhat during the teen years, and levels off at around age 25, regardless of lighting, rest, amount of close work, or vitamins taken. Most astigmatism remains fairly constant throughout life (in the absence of keratoconus).

Educational implications for refractive errors focus primarily on identification through early and continual, adequate vision screening, referral, and follow-up. Most refractive errors found in school children can be corrected with lenses. The major exception is the child with high myopia, who may be unable to be fully corrected. Magnification, higher levels of illumination, and/or telescopic aids may be indicated. Certainly, a low vision evaluation should be pursued for these children.

In the case of degenerative myopia, the associated problems should be addressed (e.g., central vision loss). Educational adjustments may need constant re-evaluation as the ocular condition progresses.

 

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Blepharitis

DESCRIPTION: A common, chronic, bilateral inflammation of the lid margins; may be staphylococcal (ulcerative) or seborrheic (non-ulcerative), or a combination of the two; may run a chronic course over a period of months or years if not treated adequately. The seborrheic type is associated with dandruff. Symptoms are itching, burning, irritation, and scaly appearance of the lid margins. Conjunctivitis, mild keratitis, chalazions and hordeola may be complications.

TREATMENT: Scalp, eyebrows, and lid margins must be kept clean and scales removed daily. Antibiotics or sulfonamide ointments are possible medications.

IMPLICATIONS: Good personal hygiene and immediate/adequate medical care are essential for the prevention and treatment.

 

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Buphthalmos

DESCRIPTION: Sometimes associated with infantile glaucoma, caused by abnormal development of the angle formed by cornea and iris; Schlemm's Canal is usually collapsed; onset at birth or before age 3 (over 80% of cases are evident by 3 months of age); usually an autosomal recessive trait. Symptoms are excessive tearing, photophobia, increased intraocular pressure, and cupping of the optic disk. The eyes usually appear abnormally large; corneal haze is not uncommon. In untreated cases, blindness occurs early. The earlier the defect appears, the less favorable the prognosis. Long-term visual prognosis is fair. Depending on when treatment is instituted, there may be lowered acuity or restricted visual fields. Must be treated surgically (goniotomy, trabeculotomy, or trabeculectomy).

TREATMENT: Surgical treatment, at the earliest possible time, is essential if vision is to be saved.

IMPLICATION: If visual fields are restricted, Orientation and Mobility instruction is indicated.

 

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Cataract

DESCRIPTION: A clouding or opacity of the lens, believed to be caused by chemical changes in the lenticular structure/material. Etiology includes: hereditary, congenital anomalies associated with disease or syndrome; infection, severe malnutrition, or drugs during pregnancy; systemic disease (e.g., diabetes); trauma (e.g., head injury or puncture wound); normal manifestation of old age. May be congenital, senile, or traumatic. Symptoms include whitish appearance of the pupil and blurred vision/decreased acuity (especially at distance). The congenital type may also include nystagmus, squint, photophobia; traumatic cataract symptoms include general redness and irritation of the eye, and may be complicated by infection, uveitis, retinal detachment, and glaucoma.

TREATMENT: There is no medical treatment - only surgical. Congenital cataracts (not caused by rubella) should be removed within the first few months of life if acuity is to develop normally; contact lenses or glasses provide the accommodative power of the missing lens. (Depending on the type of surgery, secondary cataracts sometimes reappear, and repeat surgery is necessary.) Senile cataract removal is followed by one or more of the following: cataract glasses, contact lenses, or intraocular lens implant. Complications of cataract surgery include vitreous and/or retinal detachments and glaucoma.

IMPLICATIONS: Variable lighting to reduce glare in persons with unoperated cataracts. Lighting should be from behind to reduce glare. NOTE: Children with cataracts caused by maternal rubella usually do not have surgery until at least age 2, since the live virus is present in ocular tissues many months after birth. Such children have less favorable prognoses for good acuity following surgery, since the period for retinal stimulation has passed.

Genetic counseling may be indicated.

Educational note: A child with a central, unoperated cataract may have some unusual head positions; these should be tolerated, since the child is essentially "looking around the cataract." Magnification is helpful in some cases.

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CHARGE Syndrome

From the CHARGE Syndrome Fact Sheet

CHARGE syndrome refers to a specific set of birth defects, medical problems, and developmental issues. The most distinctive birth defects are coloboma, choanal atresia and characteristic ears (external ears and small/absent semicircular canals).

Diagnosis should be made by a medical geneticist. Diagnosis is based on key features, ideally with DNA testing for CHD7 mutations.

Key features: Coloboma, Cranial nerve abnormalities, Choanal atresia, Heart defects, Characteristic external ears, Esophageal defects, Small/absent semicircular canals, Genitourinary abnormalities, CHD7 gene mutations

Incidence: One in every 8,000-10,000 births. Every person with CHARGE has a unique set of features. There is wide variation in physical features and cognitive ability.

Cause: Mutations in the CHD7 gene on chromosome 8 are found in 80-90% of cases. There is no relationship to sex, race, nationality, religion, socio-economic status, or prenatal exposure.

Recurrence: It does not usually run in families. Recurrence risk to unaffected parents is 1-2%. If a parent has CHARGE Syndrome, the risk to a baby is 50/50.

Sensory deficits: Most individuals with CHARGE have difficulty with hearing, vision and balance. This results in delayed motor development and communication. The educational term for combined vision and hearing deficits is “deafblind.”

Cognitive ability & testing: Many have decreased cognitive abilities, but 30-50% have normal intelligence. Intelligence of children with CHARGE is often underestimated due to the effects of combined hearing, vision and balance issues. Testing, therapies and educational intervention MUST take into account hearing, vision and balance status.

Lifespan: There is an increased mortality, especially in the first two years. Although individuals with CHARGE remain medically fragile, lifespan can be normal.

Outcome: Individuals with CHARGE need medical care appropriate to their particular features. In addition, early intervention and appropriate and challenging educational and vocational programs specific to their sensory needs are imperative. Although there are many problems, children with CHARGE can survive and become healthy, happy citizens.

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