Table 17-1: Development of visual acuity (approximate).

From about age 4 on, it becomes possible to elicit subjective responses by use of the illiterate "E" chart, child recognition figures, Lea figures, or HOTV cards. Usually, at the first- or second-grade level, the regular Snellen chart may be employed. Stereoacuity can be shown to develop in most infants beginning at 3 months of age, but clinical testing is not generally possible until 3-4 years of age. Absence of stereopsis, as judged with the random dot "E" test or the Titmus stereo test, is suggestive of strabismus or amblyopia and the need for further investigation.

Refraction

Objective refraction is an important part of the pediatric ophthalmic examination, especially if there is any suggestion of poor vision or strabismus. In young children, this should be performed under cycloplegia in order to overcome the child's tendency to accommodate. In many circumstances, 1% cyclopentolate drops applied twice-separated by an interval of 5 minutes-30 minutes prior to examination will provide sufficient cycloplegia, but atropine is recommended if convergent strabismus is present or the eyes are heavily pigmented. Because atropine drops are commonly associated with systemic side effects, 1% atropine ointment applied once daily for 2 or 3 days prior to examination is the recommended regimen. The parents should be warned of the symptoms of atropine toxicity-fever, flushed face, and rapid pulse-and the necessity for discontinuing treatment, cooling the child with sponge bathing, and, in severe cases, seeking urgent medical assistance. Cycloplegic refraction provides the additional advantage of good mydriasis to facilitate fundal examination.

About 80% of children between the ages of 2 and 6 years are hyperopic, 5% are myopic, and 15% are emmetropic. About 10% have refractive errors that require correction before age 7 or 8. Hyperopia remains relatively static or gradually diminishes until 19 or 20 years of age. Myopia often develops between ages 6 and 9 and increases throughout adolescence, with the greatest change at the time of puberty. Astigmatism is relatively common in babies but decreases in prevalence during the first few years of life. Thereafter, it remains relatively constant in prevalence and degree throughout life.

Anterior & Posterior Segment Examination

Further examination needs to be tailored to each child's age and ability to cooperate. Anterior segment examination in the young child relies mainly upon the use of a hand light and magnifying loupe, but slitlamp examination is often possible in babies with the cooperation of the mother-and in young children with appropriate encouragement. Measurement of intraocular pressure and gonioscopy are more of a problem and frequently necessitate examination under anesthetic. Fundal examination relies upon good mydriasis. It is generally easier in neonates and babies than in young children because they can be restrained easily by being wrapped in a blanket.

The foveal light reflection is absent in infants. Instead, the macula has a bright "mother-of-pearl" appearance with a suggestion of elevation. This is more pronounced in black infants. At 3-4 months of age, the macula becomes slightly concave and the foveal light reflection appears.

The peripheral fundus in the infant is gray, in contrast to the orange-red fundus of the adult. In white infants, the pigmentation is more pronounced near the posterior pole and gradually fades to almost white at the periphery. In black infants, there is more pigment in the fundus, and a gray-blue sheen is seen throughout the periphery. In white infants, a white periphery is normal and should not be confused with retinoblastoma. During the next several months, pigment continues to be deposited in the retina, and usually at about 2 years of age the adult color is evident.

CONGENITAL OCULAR ABNORMALITIES

Congenital defects of the ocular structures fall into two main categories: (1) developmental anomalies, of which genetic defects are an important cause; and (2) tissue reactions to intrauterine insults (infections, drugs, etc).

Congenital Abnormalities of the Globe

Failure of formation of the optic vesicle results in anophthalmos. Failure of invagination leads to a congenital cystic eye. Failure of closure produces colobomas of the iris, retina, and choroid. Cryptophthalmos occurs when the eyelids fail to separate.

Abnormally small eyes can be divided into nanophthalmos, in which function is normal, and microphthalmos, in which function is abnormal and there may be other ocular abnormalities such as cataract, coloboma, or congenital cyst.

Lid Abnormalities

Congenital ptosis is commonly due to dystrophy of the levator muscle of the upper lid. Other causes are congenital Horner's syndrome and congenital third nerve palsy.

Palpebral coloboma is a cleft of usually the upper lid, due to incomplete fusion of fetal maxillary processes. Large defects require early repair to avoid corneal ulceration due to exposure. Congenital eyelid colobomas are commonly seen in association with craniofacial disorders such as Goldenhar's syndrome.

Corneal Defects

There may be partial or complete opacity of the corneas such as is found in congenital glaucoma, forceps injuries at birth, faulty development of the corneal endothelium, developmental anterior segment abnormalities with persistent corneal-lens attachments, intrauterine inflammation, interstitial keratitis, and mucopolysaccharide depositions of the cornea as in Hurler's syndrome. The most frequent cause of opaque corneas in infants and young children is congenital glaucoma, in which the eye is often larger than normal (buphthalmos). Forceps injuries at birth may cause extensive corneal opacities with edema as a result of rupture of Descemet's membrane. These usually clear spontaneously but frequently induce anisometropic amblyopia.

Megalocornea is an enlarged cornea with normal clarity and function, usually transmitted as an X-linked recessive trait. It must be differentiated from congenital glaucoma. There are usually no associated defects.

Iris & Pupillary Defects

Misplaced or ectopic pupils (corectopia) are frequently observed. The usual displacement is upward and laterally (temporally) from the center of the cornea. Such displacement is occasionally associated with ectopic lens, congenital glaucoma, or microcornea. Multiple pupils are known as polycoria. Coloboma of the iris indicates incomplete closure of the fetal ocular cleft and usually occurs inferiorly and nasally. It may be associated with coloboma of the lens, choroid, and optic nerve. Aniridia (absence of the iris) is a rare abnormality, frequently associated with secondary glaucoma and usually due to an autosomal dominant hereditary pattern. There is a significant association between sporadic aniridia and Wilms' tumor. Frequent abdominal examinations with periodic renal ultrasonography should be performed to detect Wilms' tumor at an early treatable stage.

The color of the iris is determined largely by heredity. Abnormalities in color include albinism, due to the absence of normal pigmentation of the ocular structures and frequently associated with poor visual acuity and nystagmus; and heterochromia, which is a difference in color in the two eyes that may be a primary developmental defect with no functional loss, due to congenital Horner's syndrome or secondary to an inflammatory process.

Lens Abnormalities

The lens abnormalities most frequently noted are cataracts, though there may be faulty development, forming colobomas, or subluxation, as seen in Marfan's syndrome.

Any lens opacity that is present at birth is a congenital cataract, regardless of whether or not it interferes with visual acuity. Congenital cataracts are often associated with other conditions. Maternal rubella during the first trimester of pregnancy is a common cause of congenital cataract. Other congenital cataracts have a hereditary background.

Congenital opacities may occur at any time during formation of the lens, and the stage during which the opacity started to develop is often measurable by the depth of the opacity. The innermost fetal nucleus of the lens forms early in embryonic life and is surrounded by the embryonic nucleus. During adult life, further growth in the lens is peripheral and subcapsular.

If the opacity is small enough so that it does not occlude the pupil, adequate visual acuity is attained by focusing around the opacity. If the pupillary opening is entirely occluded, however, normal sight does not develop, and the poor fixation may lead to nystagmus and profound amblyopia. Good visual results have been reported with both unilateral and bilateral cataracts treated by early surgery. Aphakic correction is then achieved usually with extended-wear contact lenses that need to be changed frequently to maintain optimal correction.

A major management problem in congenital cataracts is the associated amblyopia. Whether this can be dealt with adequately is a major determinant in deciding whether early surgery for monocular congenital cataract is justified. In the case of bilateral congenital cataracts, the time interval between operating on the two eyes must be as short as possible if amblyopia in the second eye is to be avoided. If early surgery is to be undertaken for congenital cataracts, it is best done within the first few weeks of life, and early referral to an ophthalmologist thus is essential. Surgery for congenital cataracts is discussed in Chapter 8.

Developmental Anomalies of the Anterior Segment

Failure of migration or subsequent development of neural crest cells produces abnormalities involving the anterior chamber angle, iris, cornea, and lens. Axenfeld's syndrome, Rieger's syndrome, and Peter's anomaly are examples. Glaucoma is a major clinical problem. The associated extraocular abnormalities are probably also manifestations of abnormal neural crest development.

Vitreous Abnormalities

Remnants of the hyaloid artery may be seen on the posterior surface of the lens (Mittendorf's dot) or on the optic disk (Bergmeister's papilla).

Persistent hyperplastic primary vitreous is an important cause of leukocoria that must be differentiated from retinoblastoma, congenital cataract, and retinopathy of prematurity.

Choroid & Retina

Gross defects of the choroid and retina are visible with the ophthalmoscope. The choroidal structures may show congenital colobomas, usually in the lower nasal region, which may also include the iris and all or part of the optic nerve. Choroidal colobomas are often associated with syndromes such as CHARGE association, Aicardi's syndrome, and Goldenhar's syndrome. Posterior polar chorioretinal scarring is a pigmentary disturbance often caused by intrauterine toxoplasmosis.

Optic Nerve

Congenital anomalies of the optic nerve are relatively common. They are usually benign, such as minor abnormalities of the retinal vessels at the nerve head and tilted disks due to an oblique entrance of the nerve into the globe, but they may be associated with severe visual loss in the case of optic nerve hypoplasia or the rare central coloboma of the disk (morning glory syndrome).

Optic nerve hypoplasia is a nonprogressive congenital abnormality of one or both optic nerves in which the number of axons in the involved nerve is reduced. Previously regarded as rare, it is now understood to be a major cause of visual loss in children. The degree of visual impairment varies from normal acuity with a wide variety of visual field defects to no perception of light. Clinical diagnosis is hampered by the difficulties of examining young children and the subtlety of the clinical signs. In more marked cases, the optic disk is obviously small and the circumpapillary halo of the normal-sized scleral canal produces the characteristic "double ring sign." In other cases, the hypoplasia may be only segmental and much more difficult to detect.

Optic nerve hypoplasia is frequently associated with midline deformities, including absence of the septum pellucidum, agenesis of the corpus callosum, dysplasia of the third ventricle, pituitary and hypothalamic dysfunction, and midline facial abnormalities. Jaundice and hypoglycemia in the neonatal period and growth retardation, hypothyroidism, and diabetes insipidus during childhood are important clinical effects of the resultant endocrine disturbances. More severe intracranial abnormalities such as anencephaly and porencephaly also occur. Endocrine and neuroradiographic investigations should be undertaken in all patients with optic nerve hypoplasia except perhaps those with unilateral segmental hypoplasia who are developing normally and have no other clinically evident congenital abnormalities.

Visual performance in children with optic nerve hypoplasia may be improved by occlusion therapy. Conversely, optic nerve hypoplasia is an important cause of poor vision that does not normalize with occlusion therapy in children with or without strabismus. A number of patients with optic nerve hypoplasia are not diagnosed until adult life because of the subtlety of the optic nerve abnormality.

Extraocular Dermoids

Congenital rests of surface ectodermal tissues may lead to formation of dermoids that occur frequently in the extraocular structures. These dermoids occur most commonly superolaterally, arising from the frontozygomatic suture.

Congenital Nasolacrimal Duct Obstruction

Canalization of the distal nasolacrimal duct normally occurs before birth or during the first month of life. As many as 30% of babies will have epiphora during this time. Approximately 6% have more prolonged symptoms, of which the majority will also resolve aided by lacrimal sac massage and treatment of episodes of conjunctivitis with topical antibiotics. Nasolacrimal probing is usually curative in the remainder and is best left until about 1 year of age. In the event of acute dacryocystitis, earlier probing is often indicated. The possibility of more extensive congenital nasolacrimal anomalies should be born in mind in patients with craniofacial anomalies. Epiphora may also be due to inflammatory anterior segment disease, lid abnormalities, and congenital glaucoma.

Orbital Abnormalities

Craniofacial dysostosis (Crouzon's disease) is a rare hereditary deformity due to an autosomal dominant gene, characterized by exophthalmos, hypoplasia of the maxilla, enlargement of the nasal bones, abnormal increase in the space between the eyes (ocular hypertelorism), optic atrophy, and bony abnormalities of the region of the perilongitudinal sinus. The palpebral fissures slant downward (in contrast to the upward slant of Down's syndrome). Strabismus is also pres-ent. The strabismus is secondary to both structural anomalies of the muscles and orbital angle anomalies.

Various congenital abnormalities of skull development-due to premature closure of the skull sutures-are associated with deformities of the orbits and ocular complications resembling those associated with Crouzon's disease. Examples are oxycephaly and acrobrachycephaly.

INVESTIGATION OF THE BLIND BABY WITH NORMAL OCULAR & NEUROLOGIC EXAMINATION

An important part of pediatric ophthalmology is the investigation of babies with poor visual performance for which clinical examination reveals no ocular or neurologic cause. This presumes that defects such as optic nerve hypoplasia, albinism, and high refractive errors have been excluded. The important conditions to be considered are Leber's congenital amaurosis, cortical blindness, cone dystrophy, oculomotor apraxia, and delayed visual maturation.

Leber's congenital amaurosis-as distinct from Leber's hereditary optic neuropathy-and cone dystrophy are congenital retinal dystrophies detectable by electroretinography. Visual evoked responses and neuroimaging studies are used to diagnose cortical blindness. In oculomotor apraxia, a defect in initiation of horizontal saccades gives the impression of visual unresponsiveness, though the visual pathways are normal. Affected children develop characteristic compensatory head movements to overcome the eye movement disorder. Delayed visual maturation is a rare condition in which vision does not develop until after 3 months of age. In some cases, there may be associated ocular and neurologic abnormalities that limit final visual performance, but normal vision is attained in those in which it is an isolated condition.

POSTNATAL PROBLEMS

The most common ocular disorders of children are external infections of the conjunctiva and eyelids (bacterial conjunctivitis, hordeola, blepharitis), strabismus, ocular foreign bodies, allergic reactions of the conjunctiva and eyelids, refractive errors, and congenital defects. Since it is more difficult to elicit an accurate history of causative factors and subjective complaints in children, it is not uncommon to overlook significant ocular disorders (especially in very young children). Aside from the altered frequency of occurrence of the types of ocular disorders, the causes, manifestations, and treatment of eye disorders are about the same for children as for adults. Certain special problems encountered more frequently in infants and children are discussed below.

Ophthalmia Neonatorum (Conjunctivitis of the Newborn)

Conjunctivitis of the newborn may be of chemical, bacterial, chlamydial, or viral origin. Differentiation is sometimes possible according to the timing of presentation, but appropriate smears and cultures are essential. Antenatal diagnosis and treatment of maternal genital infections should prevent many cases of neonatal conjunctivitis. The presence of active maternal genital herpes at the time of delivery is an indication for elective cesarean section.

A. Conjunctivitis Due to Chlamydial Infection:

Chlamydia is now the commonest identifiable infectious cause of neonatal conjunctivitis in the USA. Inclusion blennorrhea due to chlamydial infection has its onset between the fifth and fourteenth days; the presence of typical inclusion bodies in the epithelial cells of a conjunctival smear confirms this diagnosis. Direct immunofluorescent antibody staining of conjunctival scrapings is a highly sensitive and specific diagnostic test. Systemic therapy with erythromycin is more effective than topical therapy and aids in the eradication of concurrent nasopharyngeal carriage, which may predispose to the development of pneumonitis.

B. Conjunctivitis Due to Chemical Trauma:

Chemical conjunctivitis caused by the silver nitrate drops instilled into the conjunctival sac at birth is most apparent during the first or second day of life. Silver nitrate conjunctivitis is usually self-limited. Silver nitrate solution (1%) should be contained in sealed single-use disposable containers. Because of the possibility of chemical conjunctivitis, some authorities advocate use of topical erythromycin or tetracycline instead for prophylaxis. Instillation of silver nitrate or an antibiotic is still required by statute in most states in the USA.

C. Conjunctivitis Due to Bacterial Infection:

Bacterial conjunctivitis, usually due to Staphylococcus aureus, Haemophilus species, Streptococcus pneumoniae, Streptococcus faecalis, Neisseria gonorrhoeae, or Pseudomonas species (the last two being the most serious because of potential corneal damage), presents between the second and fifth days after birth. Provisional identification of the causative organism may be made from conjunctival smears. Gonococcal conjunctivitis necessitates parenteral therapy with aqueous penicillin G procaine given intravenously for penicillin-sensitive strains and ceftriaxone given intravenously with topical erythromycin for penicillinase-producing strains. In all cases due to chlamydial or gonococcal infection, both parents should also be given systemic treatment. Other types of bacterial conjunctivitis require topical instillation of antibacterial agents, such as sodium sulfacetamide, bacitracin, or tetracycline, as soon as results of smears are known.

D. Conjunctivitis Due to Viral Infection:

Herpes simplex virus produces characteristic giant cells and viral inclusions on cytologic examination. Herpetic keratoconjunctivitis usually resolves spontaneously but may require antiviral therapy, particularly when associated with disseminated infection that occurs chiefly in atopic individuals.

Uveitis in Childhood

Inflammatory eye disease is relatively uncommon in children, but there are a number of important syndromes. The conditions that are seen in the same form as in adults are acute nongranulomatous anterior uveitis associated with the HLA-B27 spondyl-arthritides, intermediate uveitis, Fuchs' hetero-chromic cyclitis, and idiopathic anterior uveitis. These are treated in the same way as in adults but with care in the use of systemic steroids because of their effects on growth. Uveitis in association with juvenile rheumatoid arthritis is generally asymp-tomatic in its early stages and often remains undetected until severe loss of vision due to glaucoma, cataract, or band keratopathy, has already occurred. Regular ophthalmic screening of children with juvenile rheumatoid arthritis is essential. Girls with a pauciarticular onset of juvenile rheumatoid arthritis, especially if they have circulating antinuclear antibody, are at particularly high risk for developing uveitis. Long-term use of topical steroids and mydriatics is effective in controlling the uveitis associated with juvenile rheumatoid arthritis. (Further discussion of uveitis in children is included in Chapter 7.)

Retinopathy of Prematurity

Retinopathy of prematurity, previously called retrolental fibroplasia, has been estimated to result in 550 new cases of infant blindness each year in the United States. Improved neonatal care may reduce the percentage of babies affected but has also greatly increased the total number at risk. Retinal cryotherapy is now recommended treatment for babies with severe active disease.

Retinal vascularization proceeds centrifugally from the optic nerve, beginning at the fourth month of gestation. Retinal vessels normally reach the nasal ora serrata at 8 months and the temporal ora serrata at 9 months. Retinopathy of prematurity develops if this process is disturbed. It is usually bilateral but often asymmetric. The active phase involves changes at the junction of vascularized and avascular retina, initially as an obvious demarcation line (stage 1), followed by formation of a distinct ridge (stage 2), then extraretinal fibrovascular proliferation (stage 3). Even among patients with stage 3 disease, there is a very high incidence of spontaneous regression. Consideration is also given to the location of the changes with respect to distance from the optic disk, the extent of the disease in clock hours, and the presence of venous dilation and arterial tortuosity in the posterior segment ("plus" disease). The cicatricial phase (stages 4 and 5) is manifested by increasingly severe retinal detachment.

The major risk factors for retinopathy of prematurity are decreasing gestational age and decreasing birth weight. Although recognition of the causative role of supplemental oxygen and its restriction seems to have reduced the incidence of retinopathy of prematurity, other factors must also be important. Associated risk factors include acidosis, apnea, patent ductus arteriosus, septicemia, blood transfusions, and intraventricular hemorrhage.

It is recommended that all babies with a birth weight of 1500 g or less and those that receive prolonged supplemental oxygen therapy should undergo repeated screening for retinopathy of prematurity. As many as 60% of such babies will develop the disease, even if only in its early stages. Screening should begin at 2-4 weeks after birth and continue until the retina is fully vascularized, until the changes of retinopathy of prematurity have undergone spontaneous resolution, or until appropriate treatment has been given. Pupillary dilation is achieved with Cyclomydril (cyclopentolate 0.2% and phenylephrine 1%). In eyes with five contiguous or eight cumulative clock hours of stage 3 "plus" disease, it is recommended that retinal cryotherapy or laser photocoagulation be applied to the entire avascular retina anterior to the ridge in order to reduce the risk of subsequent cicatricial disease. Whether treatment should be given to both eyes if they both fulfill the criteria has not been determined. Such treatment should be carried out with the assistance of an experienced neonatologist and under careful monitoring because of the risks of serious systemic complications including respiratory and cardiorespiratory arrest.

Vitrectomy and lensectomy may be beneficial in cicatricial disease but probably should be reserved for babies with severe disease in both eyes.

See also Chapter 10 and discussion of oxygen toxicity in Chapter 15.

Congenital Glaucoma

Congenital glaucoma (see Chapter 11) may occur alone or in association with many other congenital lesions. Early recognition is essential to prevent permanent blindness. Involvement is often bilateral. The most striking symptom is extreme photophobia. Early signs are corneal haze or opacity, increased corneal diameter, and increased intraocular pressure. Since the outer coats of the eyeball are not as rigid in the child, the increased intraocular pressure expands the corneal and scleral tissues, producing an eye that is larger than normal (buphthalmos). The major differential diagnoses are forceps injuries at birth, developmental anomalies of the cornea or anterior segment, and mucopolysaccharidoses such as Hurler's syndrome. All of these cause corneal clouding but none produce enlargement of the globe. Useful vision may be preserved by early diagnosis and medical and surgical treatment by an ophthalmologist.

Leukocoria (White Pupil)

Parents will occasionally see a white spot through the infant's pupil (leukocoria). Although retinoblastoma must be ruled out, the opacity is more often due to cataract, retinopathy of prematurity, or persistent hyperplastic primary vitreous.

Retinoblastoma

This rare malignant tumor of childhood is fatal if untreated. In 90% of cases, the diagnosis is made before the end of the third year. In about 30% of cases, retinoblastoma is bilateral. Development of the tumor is thought to occur because of the loss-from both members of the chromosome pair-of the normally protective dominant allele at a single locus within chromosomal band 13q14 (see Chapter 18). This gene is normally responsible for production of a nuclear phosphoprotein with DNA binding activity. Loss of the allele is caused by mutations, either in the somatic retinal cells alone (nonheritable retinoblastoma) or in the germ line cells as well (heritable retinoblastoma). In heritable retinoblastoma, the genetic predisposition is inherited as an autosomal dominant trait; children of survivors have a nearly 50% chance of having the disease; and the tumor is more apt to be bilateral and multifocal. Parents who have produced one child with retinoblastoma run a 4-7% risk of having a subsequent child with the disease. Recent sequencing of the retinoblastoma gene locus now allows more specific genetic counseling and identification of individuals carrying the mutation. In sporadic cases, the tumor is usually not discovered until it has advanced far enough to produce an opaque pupil. Infants and children with presenting symptoms of strabismus should be examined carefully to rule out retinoblastoma, since a deviating eye may be the first sign of the tumor. In children of families affected by familial retinoblastoma, regular screening is important in the early detection of tumors.

Enucleation is the treatment of choice in nearly all extensive unilateral cases of retinoblastoma. In bilateral cases, conservative therapy with radiotherapy, either with episcleral plaques or external beam, and photocoagulation techniques are used increasingly to preserve the less severely affected eye. A collaborative study has been initiated to investigate the efficacy of chemotherapy in the treatment of advanced retinoblastoma.

Strabismus

Strabismus is present in about 2% of children. Its early recognition is often the responsibility of the pediatrician or the family physician. Occasionally, childhood strabismus has neurologic significance. The idea that a child may outgrow crossed eyes should be discouraged. Any child with evidence of strabismus after 3 months of age must be referred as soon as possible for ophthalmologic assessment. Neglect in the treatment of strabismus may lead to undesirable cosmetic effects, psychic trauma, and amblyopia (see below) in the deviating eye. Strabismus is covered in Chapter 12.

Amblyopia

Amblyopia is decreased visual acuity of one eye (uncorrectable with lenses) in the absence of organic eye disease. Organic eye disease may be present but insufficient to explain the level of vision.

Normal development of the physiologic mechanisms of the retina and visual cortex is determined by postnatal visual experience. Visual deprivation due to any cause, congenital or acquired, during the critical period of development (probably lasting up to age 8 in humans) prevents the establishment of normal vision in the involved eye. Reversal of this effect becomes increasingly difficult with increasing age of the child. Early suspicion and prompt referral for treatment of the underlying condition are important in preventing amblyopia.

The most common causes of amblyopia are strabismus, in which the image from the deviated eye is suppressed to prevent diplopia, and anisometropia, in which an inability to focus the eyes simultaneously causes suppression of the image of one eye and high hypermetropia, in which both eyes may become amblyopic because of failure to form a focused image in either eye. All of these conditions are treatable.

Since poor visual function in a young child may go unnoticed, routine screening is advocated to detect amblyogenic factors (eg, by photorefraction of babies for refractive errors and strabismus) or established amblyopia (by testing visual acuity at age 4).

Child Abuse (Shaken Baby Syndrome)

Child abuse is an increasingly recognized cause of childhood trauma. Making the diagnosis is essential if affected children are to be given the protection they must have, but wrong diagnosis must also be avoided if families are not to be unjustly treated.

In the shaken baby syndrome, external signs of head injury are absent, but intraretinal, preretinal, and vitreous hemorrhages are common. They are often accompanied by intracranial hemorrhage and may be indicative of the presence of subdural hemorrhage even if a computed tomography (CT) scan is normal. Unexplained retinal hemorrhages in children less than 3 years of age without external evidence of head injury is strongly suggestive of child abuse.

Blunt trauma to the head and eyes is a more readily recognized form of child abuse. Ocular manifestations include subconjunctival hemorrhage, hyphema, cataract, lens subluxation, glaucoma; retinal, vitreous, intrascleral, and optic nerve hemorrhages; and papilledema.

Victims of child abuse may present initially to ophthalmologists, and the diagnosis must be kept in mind. Ophthalmologists may also provide evidence of injuries to the head and eyes in children presenting with unexplained injuries to other parts of the body.

Learning Disabilities & Dyslexia

Ophthalmologists are often asked to evaluate children with suspected learning disabilities in order to rule out ocular disorders. Dyslexia is the most common type of learning disability and is characterized by the inability to develop good reading and writing skills. Affected children are usually of normal intelligence and have no associated physical or visual abnormalities. Parents and educators sometimes attribute learning disabilities to visual perceptual abnormalities, but most of these affected children have no visual or ocular impairment. It is believed that dyslexia is caused by a specific defect of information processing in the central nervous system. The diagnosis of learning disabilities can be readily made by education specialists, and treatment is often effective in ameliorating this condition. When asked to evaluate a child with a learning disorder, the ophthalmologist should perform a complete examination and treat any refractive, strabismic, or amblyopic conditions identified. It is important to advise the parents that ocular or visual abnormalities generally do not lead to learning disabilities, and special educational programs may be necessary to treat these children. "Vision training," "visual therapy," and "perceptual training" programs have not been evaluated in a scientifically controlled, randomized, or prospective fashion, and thus their efficacy has not been proved. Ophthalmologists should provide indicated care of ocular problems and refer patients to appropriate educational programs for diagnosis and treatment of learning disabilities.

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List of Tables

Table 17-1: Development of visual acuity (approximate).

10.1036/1535-8860.ch17

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