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Special Subjects of Pediatric Interest

Paul Riordan-Eva, FRCOphth

Pediatric ophthalmology offers particular challenges to the ophthalmologist, pediatrician, and family physician. Symptoms are often nonspecific, and the usual examination techniques require modification. Development of the visual system is still occurring during the first decade of life, with the potential for amblyopia even in response to relatively mild ocular disease. Because the development of the eye often reflects organ and tissue development of the body as a whole, many congenital somatic defects are mirrored in the eye. Collaboration with pediatricians, neurologists, and other health workers is essential in managing these conditions. Similar collaboration is required in assessing the educational needs of any child with poor vision.

Details of the embryology and the normal postnatal growth and development of the eye are discussed in Chapter 1.

EXAMINATION OF NEONATES

Every newborn’s physical examination should include assessment for normal symmetrical external ocular anatomy and normal red reflex in each eye (Table 17–1). If any abnormality is identified, full ophthalmological assessment is required, for which the necessary instruments are hand light, loupe, direct and indirect ophthalmoscopes, and occasionally a portable slitlamp. Any congenital abnormality may be associated with nonocular abnormalities requiring further investigations.

Table 17–1. Pediatric Eye Examination Schedule

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Vision

Assessment of vision of the neonate is limited to observing the following response to a visual target, the most effective being a human face. Visual fixation and following movements can be demonstrated in most neonates; however, during the first 2 months of life, some do not demonstrate consistent fixation behavior and following (smooth pursuit) eye movements may be coarse and jerky.

External Inspection

The eyelids are inspected for growths, deformities, lid notches, and symmetric movement with opening and closing of the eyes. The absolute and relative size of the eyeballs is noted, as well as their position and alignment. The size and luster of the corneas are noted, and the anterior chambers are examined for clarity and iris configuration. The size, position, and light reaction of the pupils are also noted. The pupils are normally relatively dilated until 29 weeks of gestation, at which time the pupillary light response first becomes apparent. The light response is not a reliable test until 32 weeks of gestation. Anisocoria of 0.5 mm can be seen in as many as 20% of neonates. It is important to carefully examine the pupils of any infant with ptosis, looking for anisocoria, as Horner’s syndrome, while usually benign, can be due to neuroblastoma.

Ophthalmoscopic Examination

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The red reflex is examined with a direct ophthalmoscope. Any abnormality requires direct and/or indirect ophthalmoscopy through dilated pupils. (Phenylephrine 2.5% and cyclopentolate 1% or tropicamide 1% are generally safe in full-term neonates. They may have adverse effects on blood pressure and gastrointestinal function in premature neonates and those with lightly pigmented eyes, for whom combined cyclopentolate 0.2% and phenylephrine 1% [Cyclomydril] should be used.)

Physiologic cupping of the disk is usually not seen in premature infants and is rarely seen at term. In neonates, the optic disk may appear gray, resembling optic nerve atrophy, but if so, there is gradual change to the normal adult pink color by about 2 years of age. Fundal hemorrhages are present in up to 50% of newborns, usually clearing completely within a few weeks and leaving no permanent visual dysfunction. In addition to fundal abnormalities, ophthalmoscopy reveals corneal, lens, and vitreous opacities.

EXAMINATION OF INFANTS & YOUNG CHILDREN

Vision

Vision should be assessed at each “well child” examination. It is best not to wait until the child is old enough to respond to visual charts, as these may not furnish accurate information until school age. During the first 3–4 years, estimations of vision generally rely on observation and reports about the child’s behavior both at play and during interactions with parents and other children. However, seemingly normal visual performance is possible with relatively poor vision. Obviously abnormal performance probably reflects extremely poor vision. The influence of visual impairment on motor and social development must always be borne in mind.

The pupillary responses to light are only a gross test of visual function and are reliable only for ruling out complete dysfunction of the anterior visual or efferent pupillary pathways. The ability to fixate and follow a target is much more informative. The target must be appropriate to the age of the child. Binocular following and convergence are best examined first to establish the child’s cooperation. Each eye should then be tested separately, preferably with occlusion of the fellow eye by an adhesive patch. Comparison of the performance of the two eyes will give useful information about their relative acuities. Resistance to

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occlusion of one eye suggests that it is the preferred eye and the fellow eye has comparatively poor vision. In nystagmus with a latent component (increased intensity with occlusion of one eye), occlusion of either eye is likely to be resisted because of its adverse effect on visual acuity. Manifest nystagmus may be indicative of an anterior visual pathway disorder or other central nervous system disease (see Chapter 14). After 3 months of age, strabismus, detected by examining the relative position of the corneal light reflections, may be indicative of poor vision in the deviated eye, particularly if this eye does not or is slow to take up fixation of a light upon occlusion of the fellow eye (see Chapter 12).

The developing sensory system can be assessed by the quantitative techniques of optokinetic nystagmus, forced-choice preferential looking methods, and visually evoked responses (see Chapter 2). Although visually evoked potentials have suggested that normal adult visual acuity is attained before 2 years of age, this is probably an overestimate and it is likely that 3–4 years of age is a more accurate estimate (Table 17–2). Forced-choice preferential looking methods provide reliable and relatively easy assessment of visual acuity in preverbal children, even in the very young. However, they tend to overestimate visual acuity in amblyopia.

Table 17–2. Development of Visual Acuity (Approximate)

From about age 4, it is possible to elicit subjective responses with the illiterate “E” chart, child recognition figures, Lea figures, or HOTV cards. Usually, at the firstor 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 should prompt further investigation.

Refraction

Objective refraction is a crucial part of pediatric ophthalmic examination, especially if there is any suggestion of poor vision or strabismus. In young

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children, this should be performed with cycloplegia to prevent accommodation. In most circumstances, cyclopentolate 1% drops applied twice—separated by an interval of 5 minutes—30 minutes prior to examination is sufficient, but atropine may be required if convergent strabismus is present or the eyes are heavily pigmented. Atropine drops can be associated with systemic side effects, so atropine 1% ophthalmic ointment applied once daily for 2 or 3 days prior to examination is recommended. 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 for examination of the fundus.

About 80% of children between the ages of 2 and 6 years are hyperopic, 5% are myopic, and 15% are emmetropic. Since hyperopia can be overcome by accommodation and tends during childhood to decrease with time, only about 10% of children require correction of refractive error before age 7 or 8. 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. Asymmetric refractive error can lead to (anisometropic) amblyopia, which is detected only by assessing visual acuity.

Anterior & Posterior Segment Examination

Further examination needs to be tailored to each child’s age and ability to cooperate. It is generally easier in neonates and babies than in young children because they can be restrained easily by being wrapped in a blanket, and examination is often easily accomplished by allowing the infant to feed or nurse during the examination. Anterior segment examination in the young child may rely on the use of hand light and 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 frequently necessitate examination under anesthesia. Fundus examination relies on good mydriasis.

In infants, there is no foveal light reflection. The macula has a bright “mother-of-pearl” appearance with a suggestion of elevation, which is more pronounced in heavily pigmented infants. At 3–4 months of age, the macula becomes slightly concave and the foveal light reflection appears. The peripheral

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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 at the periphery to almost white, which should not be confused with retinoblastoma. In more heavily pigmented infants, a gray-blue sheen is seen throughout the periphery. 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 optic vesicle/fissure closure produces colobomas of the iris, retina, and/or 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 (see Chapter 4). Other causes are congenital Horner’s syndrome and congenital third nerve palsy. Severe ptosis can lead to unilateral astigmatism or visual deprivation, and thus cause amblyopia.

Palpebral coloboma is a cleft of either the upper or lower eyelid 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.

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Corneal Abnormalities

Partial or complete opacification of the cornea at birth or during childhood may be due to congenital glaucoma, in which case the eye is often larger than normal (buphthalmos); forceps injury at birth, which may cause extensive corneal opacities with edema as a result of rupture of Descemet’s membrane that usually clear spontaneously but frequently induce anisometropic amblyopia; 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. Megalocornea is an enlarged cornea with normal clarity and function, usually transmitted as an X-linked recessive trait and an isolated anomaly.

Iris & Pupillary Defects

Displacement of the pupil (corectopia) is usually upward and outward. It may be associated with ectopic lens, when it is usually bilateral, congenital glaucoma, or microcornea. Polycoria means multiple pupils. 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, and involvement of these structures can be associated with profound reduction of vision. Aniridia (absence of the iris) is a rare abnormality, frequently associated with secondary glaucoma (see Chapter 11) and usually due to an autosomal dominant hereditary pattern. There is a significant association with Wilms’ tumor for which the risk can be determined by genetic testing, thus identifying the children who need to undergo screening by renal ultrasound every 3 months until age 8.

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 (see Chapter 8).

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Others are faulty development, such as coloboma or subluxation, which occurs 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 in emerging countries. Other congenital cataracts have a hereditary background, with autosomal dominant transmission being the most common in developed countries. The time of onset of congenital cataract is often identifiable by its position. 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 a congenital cataract is too small to occlude the pupil, adequate visual acuity is attained by viewing around it. If the pupil is occluded, normal sight does not develop and visual deprivation may lead to nystagmus and profound irreversible amblyopia. Good visual results have been reported with both unilateral and bilateral cataracts treated by early surgery with prompt correction of aphakia and amblyopia therapy. Aphakic correction is done by using extended-wear contact lenses with the power changed frequently to maintain optimal correction as the globe grows and the refractive status changes or by implantation of an intraocular lens, but determining the appropriate power is difficult.

A common management problem in congenital cataracts is the associated amblyopia. Whether this can be dealt with adequately is the 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 2 months of life, and thus prompt referral to an ophthalmologist is essential.

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. Mutations of the PAX6 gene cause many of these developmental anomalies of the eye, such as Axenfeld-Rieger syndrome and Peters’ anomaly. Glaucoma is a major clinical problem that often requires surgical intervention, as good control

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of intraocular pressure is required before considering corneal transplantation.

Congenital Glaucoma

Congenital glaucoma (see Chapter 11) may occur alone or in association with many other congenital lesions. It is often bilateral. Early diagnosis and treatment are essential to preserve useful vision and prevent permanent blindness. The most striking symptom is extreme photophobia. Early signs are corneal haze or opacity, increased corneal diameter, and increased intraocular pressure. Since in childhood the outer coats of the eyeball are not rigid, the increased intraocular pressure expands the cornea and sclera, 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, of which none produce enlargement of the globe.

Vitreous Abnormalities

In premature infants, remnants of the tunica vasculosa lentis are frequently visible, in front of and/or behind the lens. Usually they have regressed by term, but rarely, they remain permanently and appear as a complete or partial “cobweb” in the pupil. At other times, remnants of the primitive hyaloid system fail to absorb completely, leaving either a cone on the optic disk that projects into the vitreous (Bergmeister’s papilla) or a gliotic tuft on the posterior lens capsule (Mittendorf’s dot). Persistent hyperplastic primary vitreous is an important cause of leukocoria that must be differentiated from retinoblastoma, congenital cataract, and retinopathy of prematurity.

Choroid & Retina

Choroidal colobomas, usually in the lower nasal region and sometimes involving the iris and all or part of the optic nerve, are often associated with syndromes such as CHARGE, Aicardi’s, in which another feature are focal chorioretinal lesions (lacunae), and Goldenhar’s (hemifacial microsomia). Posterior polar chorioretinal scarring is a feature of toxoplasmosis and other maternally acquired intrauterine infections.

Optic Nerve

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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) (see Chapter 14).

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 recognized 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 consequences. 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.

Visual performance in children with optic nerve hypoplasia occasionally 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. They occur most commonly superolaterally, arising from the frontozygomatic suture.

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Congenital Nasolacrimal Duct Obstruction

Canalization of the distal nasolacrimal duct normally occurs before birth or during the first month of life, with as many as 30% of infants having 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 deferred until about 1 year of age. In the event of acute dacryocystitis, earlier probing is often indicated. In a few cases, temporary intubation and/or balloon catheter dilation of the lacrimal system or lacrimal surgery is required. The possibility of more extensive congenital nasolacrimal anomalies should be borne in mind in patients with craniofacial anomalies. Epiphora may also be due to inflammatory anterior segment disease, lid abnormalities, and congenital glaucoma.

Orbital Abnormalities

Crouzon’s syndrome is a rare autosomal dominant premature fusion of the skull bones (craniosynostosis) characterized by shallow orbits with proptosis, hypoplasia of the maxilla, enlargement of the nasal bones, abnormal increase in the space between the eyes (ocular hypertelorism), and optic atrophy. The palpebral fissures slant downward (in contrast to the upward slant of Down syndrome). Strabismus due to structural anomalies of the muscles and orbit is often present.

INVESTIGATION OF THE BLIND BABY WITH NORMAL OCULAR & NEUROLOGIC EXAMINATION

An important part of pediatric ophthalmology is the investigation of infants 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, ocular motor apraxia, and delayed visual maturation.

Leber’s congenital amaurosis and cone dystrophy are congenital retinal dystrophies that cause poor vision in infants who present with large-amplitude

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nystagmus and poor visual fixation. These infants will frequently demonstrate eye poking, pressing, or rubbing (oculodigital sign). Diagnosis is confirmed by electroretinography. Cerebral (cortical) visual impairment, a common cause of vision impairment in premature infants and infants who sustained perinatal hypoxic-ischemic encephalopathy, is the leading cause of infantile blindness in developed countries. Diagnosis is confirmed by neuroimaging and clinical history. In ocular motor apraxia (infantile-onset saccade initiation delay), a defect in initiation of horizontal saccades gives the impression of visual unresponsiveness, although 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 2 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), amblyopia, strabismus, ocular foreign bodies, allergic reactions of the conjunctiva and eyelids, and refractive errors. 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).

Ophthalmia Neonatorum (Conjunctivitis of the Newborn)

Conjunctivitis of the newborn may be chemical, bacterial, chlamydial, or viral. 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 may be an indication for elective cesarean section (see Chapter 20). In all cases of chlamydial, gonococcal, and herpes simplex virus neonatal conjunctivitis, the baby must be tested and treated for other sexually transmitted

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infections, and the mother and her sexual partners should be assessed and treated.

A. Chlamydial Conjunctivitis

Chlamydia is now the most common identifiable infectious cause of neonatal conjunctivitis in the United States. Typically its onset is between 5 and 14 days after birth. Characteristic inclusion bodies are seen in epithelial cells of a conjunctival smear. Direct immunofluorescent antibody staining of conjunctival scrapings is a highly sensitive and specific diagnostic test, and polymerase chain reaction is now clinically available. 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. Bacterial Conjunctivitis

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—typically presents between 2 and 5 days after birth. Provisional identification of the causative organism may be made from conjunctival smears. Gonococcal conjunctivitis necessitates parenteral therapy with ceftriaxone, or cefotaxime if there is hyperbilirubinemia. Other types of neonatal bacterial conjunctivitis require topical instillation of antibacterial agents, such as sodium sulfacetamide, bacitracin, or polymyxintrimethoprim, as soon as results of smears are known.

C. Viral Conjunctivitis

Herpes simplex virus produces characteristic giant cells and viral inclusions on cytologic examination. Herpetic keratitis occurring in children younger than 6 months necessitates admission to hospital for lumbar puncture with polymerase chain reaction evaluation to determine whether there is central nervous system systemic infection and whether systemic therapy is needed. Herpetic keratoconjunctivitis usually resolves spontaneously but may require antiviral therapy, particularly when associated with disseminated infection that occurs chiefly in atopic individuals.

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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 spondylarthritides, intermediate uveitis, Fuchs’ heterochromic iridocyclitis, and idiopathic anterior uveitis. These are treated in the same way as in adults (see Chapter 7), but with care in the use of systemic steroids because of their effects on growth. Uveitis in association with juvenile idiopathic arthritis is generally asymptomatic in its early stages and, if undetected, may produce severe loss of vision due to glaucoma, cataract, or band keratopathy (see Figure 7–9). Regular ophthalmic screening of children with oligoarticular disease, which generally occurs in girls with positive antinuclear antibodies, is essential. Long-term use of topical steroids and mydriatic/cycloplegic agents is often effective in controlling the uveitis, but some patients will require systemic immunosuppression, possibly with agents other than steroids (see Chapters 7 and 15).

Retinopathy of Prematurity

Retinopathy of prematurity (ROP) (see Chapter 10) has been estimated to result in 550 new cases of infant blindness each year in the United States. The major risk factors for ROP 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 ROP, other factors contribute to the onset and severity of the disease. They include acidosis, apnea, patent ductus arteriosus, septicemia, blood transfusions, and intraventricular hemorrhage. Improved neonatal care has reduced the percentage of babies affected but has also greatly increased the total number at risk.

A. Pathogenesis and Progression

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. ROP 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; Table 17–3), followed by

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formation of a distinct ridge (stage 2), then extraretinal fibrovascular proliferation (stage 3). Even among patients with stage 3 disease, there is a high incidence of spontaneous regression. Consideration is also given to the location of the changes with respect to distance from the optic disk (zone I or II), 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 defined by increasingly severe retinal detachment, which results in profound vision impairment even with vitreoretinal surgery.

Table 17–3. Stages of Retinopathy of Prematurity

B. Screening and Treatment

All babies with a birth weight of 1500 g or less or gestational age at birth of 30 weeks or less and some infants with a birth weight between 1500 and 2000 g or gestational age at birth greater than 30 weeks, such as those who receive cardiorespiratory support, should undergo screening by a suitably experienced ophthalmologist. Up to 60% of such babies are affected, if only by the early stages. Onset of serious ROP correlates best with postmenstrual age. If gestational age at birth is 27 weeks or less, screening should begin at 31 postmenstrual weeks, or possibly earlier if gestational age at birth is less than 25 weeks. If gestational age at birth is 28 weeks or more, screening should begin at 4 weeks chronological age. Screening is repeated until the retina is fully vascularized, the retinal changes have undergone spontaneous resolution, or appropriate treatment has been given. Cyclomydril (cyclopentolate 0.2% and phenylephrine 1%) is convenient to dilate the pupils. Tropicamide 0.5% can be used instead of cyclopentolate. If only higher concentrations (2.5–5%) of phenylephrine are available, the risk of systemic adverse effects must be borne in mind.

Laser ablation of the immature retina delivered by a head-mounted indirect ophthalmoscope diode or argon laser is the recommended treatment and should be undertaken once there is any stage disease close to the optic disk (zone I) with plus disease, stage 3 disease in zone I, or stage 2 or 3 disease with plus disease.

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Previously cryotherapy was the treatment of choice, but there was a higher incidence of complications. Intravitreal injections of anti–vascular endothelial growth factor (VEGF) agents have been shown to be effective in threshold and prethreshold ROP, with regression of neovascular changes and continued peripheral growth of normal retinal vessels. Any 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. Vitreoretinal surgery may be appropriate for eyes with stage 4 or 5 disease but is only recommended when such disease occurs in the better eye as the visual prognosis continues to be poor.

In a significant number of infants with ROP, there is spontaneous regression. Peripheral retinal changes of regressed ROP include peripheral folds and retinal breaks and changes in the posterior retina include straightening of the temporal vessels, temporal stretching of the macula, and retinal tissue that appears to be dragged over the disk. Other ocular findings of regressed ROP include myopia (which may be asymmetric), strabismus, cataract, and angle-closure glaucoma.

Leukocoria (White Pupil)

Parents will occasionally see, or identify on photographs as absence of the “redeye” effect, a white spot through the infant’s pupil (leukocoria). A rare but important cause is retinoblastoma, a rare malignant tumor of childhood that is fatal if untreated and, in 90% of cases, is diagnosed before the end of the third year (see Chapter 10). Leukocoria is more often due to cataract, retinopathy of prematurity, persistent hyperplastic primary vitreous, or refractive error in the case of absence of the red-eye effect, but any affected child must be seen urgently to ensure that vision and life-threatening conditions are diagnosed and treated promptly.

Strabismus

Strabismus (see Chapter 12) 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.

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Amblyopia

Amblyopia is decreased visual acuity in the absence of sufficient organic eye disease to explain the level of vision.

Normal development of the 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. 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. High degrees of hypermetropia or astigmatism may cause bilateral amblyopia. Successful treatment depends on early detection and compliance with treatment, which involves appropriate correction of refractive error and then, if necessary, occlusion therapy (patching) of the sound eye for several hours a day or the use of atropine penalization (pharmacologic blurring of the sound eye) daily for several weeks. No matter what therapy is instituted, visual acuity of both eyes must be monitored.

Since poor visual function in a young child may go unnoticed, routine screening by the age of 4 years is recommended (see Chapter 20).

Child Abuse

Child abuse is an important cause of childhood trauma, and its prompt recognition is essential if affected children are to be appropriately protected, 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 cerebral injury, even if computed tomography is normal. Retinal hemorrhages in children less than 3 years of age without external evidence of head injury is strongly suggestive of child abuse, as long as other causes such as blood dyscrasia have been excluded.

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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. The ophthalmologist should work in close collaboration with the pediatrician to ensure that all other potential causes of hemorrhage have been evaluated and to document all other injuries of the child.

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 should be made by education specialists. 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 error, strabismus, or amblyopia as required. 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.

REFERENCES

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