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DESCRIPTION:(also known as optic neuritis) A general term implying inflammation of the optic nerve, but also includes degeneration or demyelinization of the optic nerve; included retrobulbar neuritis, a condition affecting the optic nerve behind the optic disk (i.e., there are no visible changes of the optic nerve head unless optic atrophy has occurred). Causes include demyelinating diseases (e.g., multiple sclerosis, postinfectious encephaIomyelitis), systemic infections (viral - polio, flu, mumps, measles - and bacterial - pneumonia et. Al.), nutritional and metabolic diseases (diabetes, pernicious anemia, hyperthyroidism), Leber's Disease, secondary complications of inflammatory diseases (e.g., sinusitis, meningitis, tuberculosis, syphilis, chorioretinitis, orbital inflammation), toxic reactions (to tobacco, methanol, quinine, arsenic, salicylates, lead), and trauma. Papillitis is differentiated from papilledema; it is unilateral instead of bilateral, shows less elevation of the nerve head, and sluggish pupillary response. In optic neuritis, there is usually a severe but temporary loss of vision for several days and pain in the eye when moved.

TREATMENT: Treatment is directed toward the underlying cause. Systemic corticosteroids may be helpful, but the tendency without treatment is toward improvement. Visual acuity usually begins to improve in 2-3 weeks, and sometimes returns to normal in a few days.

IMPLICATIONS: Central scotomas are the most common visual field defect, but any unilateral field change is possible. A single attack of optic neuritis is not likely to leave severe damage, but permanent and significant visual loss is probable over a period of years when recurrent attacks are experienced.

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Optic Atrophy

DESCRIPTION: Dysfunction of the optic nerve; may be congenital or acquired. If congenital, it is usually hereditary. The milder form is autosomal dominant and has a gradual onset of deterioration in childhood but little progression thereafter; the more severe form is autosomal recessive and is present at birth or within 2 years; this form is accompanied by nystagmus. Leber's Disease has an unclear mode of inheritance but is suspected of being X-linked, since it only rarely occurs in women; optic neuropathy occurs more commonly in 20-30 year old males; some vision is retained but there are varying degrees of impairment. The acquired type of optic atrophy may be due to vascular disturbances (occlusions of the central retinal vein or artery or arteriosclerotic changes within the optic nerve itself), may be secondary to degenerative retinal disease (e.g., papilledema or optic neuritis), may be a result of pressure against the optic nerve, or may be related to metabolic diseases (e.g., diabetes), trauma, glaucoma, or toxicity (to alcohol, tobacco, or other poisons). Loss of vision is the only symptom. Pale optic disk and loss of pupillary reaction are usually proportionate to the visual loss.

TREATMENT: There is no known treatment, since degeneration of optic nerve fibers is irreversible. Since changes in visual function occur gradually (over weeks or months), ophthalmoscopic observations are not reliable predictors of functioning until disk cupping and marked pallor are noted; these are unfavorable signs. Visual loss as a result of pressure against the optic nerve may be restored if the cause is identified and treated early. Optic atrophy secondary to vascular, traumatic, degenerative, and some toxic causes has a negative prognosis.

IMPLICATIONS: Enhancing visual function may require high levels of illumination and enlarged print with high contrast; magnification may be useful in some cases. Color perception may be impaired.

Since it is impossible to identify exactly which fibers of the optic nerve are involved, it should not be assumed that the optic nerve is not functioning at all; a better assumption might be that the visual stimulus is experiencing difficulty in getting to the brain; if and when it arrives, it may be in distorted or incomplete form. Thus, perceptual function may be greatly affected. Moreover, day-to-day classroom performance of a student with optic atrophy may fluctuate with no apparent reason. The child may not be aware of these fluctuations; the classroom teacher should be alerted to their possibility.

NOTE: Optic nerve hypoplasia should not be confused with optic atrophy. Optic nerve hypoplasia is an undeveloped optic nerve due to a neurological insult early in the prenatal developmental period; the optic nerve has started to develop, but regresses. Ophthalmologically, the nerve head appears unusually small, and is surrounded by a white "halo" of scleral tissue showing through. The anomaly appears to be related to chronic alcohol and drug abuse by the mother during the prenatal period. CAT scans of these children reveal defects in the septum pelucidum and posterior corpus callosum; those who lack the septum pellucidum have spatial orientation problems. At least one third of these children had low APGAR scores and end up to have endocrine problems. Most have some type of neurological problems. Visual acuity ranges from normal to severely impaired.

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DESCRIPTION: Involuntary, rhythmical, repeated oscillations of one or both eyes, in any or all fields of gaze; may be pendular (with undulating movements of equal speed, amplitude, and duration, in each direction) or jerky (with slower movements in one direction, followed by a faster return to the original position). Movements may be horizontal, vertical, oblique, rotary, circular, or any combination of these. Generally, the faster the rate, the smaller the amplitude (and vice versa). The defect is classified according to the position of the eyes when it occurs. Grade I occurs only when the eyes are directed toward the fast component; grade II occurs when the eyes are also in their primary position; grade III occurs even when the eyes are directed toward the slow component. The cause of nystagmus is unknown. Reduced acuity is caused by the inability to maintain steady fixation. Head-tilting may decrease the nystagmus and is usually involuntary (toward the fast component in jerky nystagmus, or in such a position to minimize pendular nystagmus). Head nodding often accompanies congenital nystagmus. Dizziness or vertigo may be experienced if oscillopsia (illusory movements of objects) occurs. Nystagmus may be induced with an optokinetic drum or through the stimulation of the semicircular canals. Congenital nystagmus of the pendular type usually accompanies congenital visual impairment (e.g., corneal opacity, cataract, albinism, aniridia, optic atrophy, chorioretinitis). Nystagmus may also accompany a number of neurological disorders, and may be a reaction to certain drugs (including barbiturates).

TREATMENT: There is no known treatment, however, certain types of jerky nystagmus (commonly Grade I types) show spontaneous improvement in childhood (up to age 10). This type may also be amenable to muscle surgery (essentially, a repositioning of muscles to take advantage of the point of least nystagmus, or position of relative rest).

IMPLICATIONS: With the exception of brief experiences of oscillopsia, most individuals with nystagmus perceive objects as being stationary. It is believed that the brain is responsible for the perceptual adjustment.

Educationally, children with nystagmus (who may tend to lose their place in beginning reading instruction) may be helped through the use of a typoscope (card with a rectangular hole, to view one word or line at a time) or an underliner (card or strip of paper to "underline" the line being read). As children with nystagmus mature, they seem to need these support devices less often.

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DESCRIPTION: Abnormal smallness of one or both eyes; congenital, and almost always hereditary (usually recessive, but may also be dominant). Other ocular abnormalities also occur, including cataract, glaucoma, aniridia, and coloboma. Systemic and anatomic abnormalities also often occur; these include: polydactyly, syndactyly, clubfoot, polycystic kidneys, cystic liver, cleft palate, and meningoencephalocele. Deficient vision is the rule.

TREATMENT: Lens correction for refractive errors, often tinted; lighting according to needs, to control glare.

IMPLICATIONS: Genetic counseling is indicated.

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Macular Degeneration

DESCRIPTION: Hereditary and untreatable group of diseases which affect the macular area of the retina. When the disease affects the choriocappilaris, as in central areolar choroidal sclerosis, there is gradual loss of central vision in middle life. Genetically, this type of macular degeneration is autosomal dominant or recessive. Other types of macular degeneration affect the pigment epithelium. Stargardt-Behr disease is transmitted genetically as an autosomal recessive factor; it results in gradual deterioration of the pigment epithelium, which begins at different ages and progresses at different rates; rate and degree of visual loss varies from family to family. In Best's vitelliform macular degeneration (an autosomal dominant genetic pattern), changes are confined to the macula. Initially, it resembles a poached egg "sunny side up;" later, the "yolk" appears scrambled, and central vision is seriously decreased. (see also Scotomas)

TREATMENT: Untreatable.

IMPLICATIONS: Identification of the type of deterioration may be helpful in educational planning, however, the wide range of resulting visual loss and rate of degeneration makes prediction of final visual status impossible. Regular fundus examination may indicate changes which will have implications for educational and/or rehabilitative planning.

Genetic counseling is indicated.

Eccentric viewing may be observed in an attempt to utilize peripheral input.

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DESCRIPTION: A rare, trilateral, degenerative disease; inherited as an autosomal recessive trait; affects all races; appears in the second decade of life, and progresses slowly between the ages of 20 and 60; associated with a number of other diseases, including Down's syndrome, atopic dermatitis, retinitis pigmentosa, aniridia, Marfan's syndrome. Keratoconus is literally an increasing conical shape to the cornea; the central cornea thins and may rupture in advanced stages. Blurred vision is the only symptom, however, examination shows a distorted corneal reflection and an inability to see the fundi.

TREATMENT: Contact lenses improve visual acuity in the earliest stages. A corneal transplant is indicated when the corrected visual acuity decreases beyond the patient's tolerance for functional activities.

IMPLICATIONS: If a corneal transplant is done before corneal thinning occurs, about 80%-95% of patients retain reading vision.

Genetic counseling may be indicated.

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DESCRIPTION: A term used to define a wide variety of corneal infections, irritations, and inflammations; since each type of condition is unique, medical diagnosis and treatment is essential. Corneal ulcers are commonly caused by bacterial or fungal invasions following superficial corneal abrasions; among the common infectious agents are: staphyloccus, streptococcus, herpes (both simplex and zoster), adenovirus, rubeola, rubella, mumps, trachoma, infectious mononucleosis, and pneumococcus; also at fault may be Vitamin A deficiency or broad spectrum antibiotic drug reactions. Corneal ulcers may also follow trauma, may be associated with other eye infections (e.g., conjunctivitis), may be related to other corneal disorders (e.g., degenerative conditions, or ptosis, which may cause a "dry eye"), or may arise from a variety of systemic disorders (especially those of autoimmune origin). Symptoms of corneal infection include extreme pain and photophobia.

TREATMENT: Medical treatment is absolutely essential - even a delay of a few hours can affect the ultimate visual result. The causative factors must be determined through laboratory analysis of scrapings; medical treatment (i.e., medication) varies according to the cause.

IMPLICATIONS: It is extremely important to treat keratitis before corneal tissue is destroyed and scar tissue is formed. Because the pain is so severe in keratitis, the patient usually welcomes medical attention. However, if the cornea loses its sensitivity (as in trauma, surgery, or damage to the trigeminal nerve), ulcers can develop without accompanying pain.

The implications for personal hygiene are evident, especially with children. Handwashing during periods of illness and following toileting is of vital importance as a preventive measure.

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DESCRIPTION: A common staphyloccal infection of the lid glands; essentially an abscess, with pus formation; symptoms include swelling, redness, and pain. Two types are classified: internal hordeolum (relatively large, affecting the meibomian glands; may point toward the skin or toward the conjunctive) and external hordeolum (also known as a "sty;" smaller and more superficial; an infection of the glands of Moll or Zeiss; painful; always points toward the skin side of the lid margin).

TREATMENT: Both types of hordeola are treated with warm compresses for 10-15 minutes 3-4 times a day; if the condition does not improve within 48 hours, incision and drainage of the pus is indicated. Antibacterial ophthalmic ointment is also helpful.

IMPLICATIONS: Although hordeola are not visually threatening, they are uncomfortable and should be treated; prevention of infection spreading to other parts of the eye is a consideration. A large internal hordeolum has the potential to affect the entire lid through accompanying cellulitis.

Personal hygiene, especially for children, is an indication.

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DESCRIPTION: Disease of the choroid; caused by an invasion of a fungal organism; transmitted by airborne spores found in dried animal excrement; the peripheral fundus has "punched-out" spots similar to healed chorioretinal lesions, but smaller and less pigmented. Macular involvement may occur later (believed to be a result of earlier choroidal sensitization and subsequent reinfection); these macular lesions may progress to hemorrhagic detachments. There is no vitreous haze. There is a positive reaction to a skin test for the disease. It seems to occur more often in the eastern half of the United States.

TREATMENT: Many treatments have been advocated, including systemic corticosteroids, antihistamines, and photocoagulation of perimacular leakage, but results have been questionable in all cases. Once disciform changes begin, prognosis is very poor.

IMPLICATIONS: In the initial stages, when only the peripheral fundus is affected, the vision is not affected (except for peripheral scotomas, which do not usually interfere with visual functioning). If the macula becomes involved, decreased central acuity, deficient color vision, and central scotoma can cause considerable loss of visual function. Optical aids may be helpful in these cases.

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DESCRIPTION: Literally, "half vision;" a condition resulting from malfunction or damage to one side of the optic tract (see diagram below). Images from only one half of each eye reach the brain; thus, there is only reception of half-fields for each eye.

Hemianopsia graphic - described in text

TREATMENT: There is no treatment for hemianopia itself; the cause (e.g., tumor or hemorrhage) should be investigated and treated if possible. Visual fields losses can sometimes be alleviated with prism lenses, but their efficient use depends on the individual user (motivation, perceptual ability, etc.). Orientation and Mobility adjustments may be indicated. Reading may be affected, depending on whether the loss is in the right (in reading, the "anticipatory" field) or left fields.

IMPLICATIONS: Examination of the diagram will suggest that different types of visual losses occur when sites of malfunction differ (e.g., a tumor affecting the optic chiasm will cause visual impairment in both eyes, but a tumor affecting either optic nerve will affect only one eye).

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