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.

All infants should have their eyes examined as a part of the newborn physical examination, and the practitioner should look for the presence of a normal red reflex in both eyes, normal external ocular anatomy, and symmetry between the eyes. A careful eye examination soon after birth may reveal congenital abnormalities that suggest the presence of abnormalities elsewhere in the body and the need for further investigations. A pediatric examination table is presented in Table 17–1.

The instruments required for the ocular examination of the newborn are a good hand light, direct and indirect ophthalmoscopes, a loupe for magnification, and occasionally a portable slitlamp. Phenylephrine 2.5% and cyclopentolate 1% or tropicamide 1% are generally safe for pupillary dilation in full-term neonates, although even these concentrations may have adverse effects on blood pressure and gastrointestinal function in premature neonates and those with lightly pigmented eyes; in these instances the combination of cyclopentolate 0.2% and phenylephrine 1% (Cyclomydril) should be used to dilate the pupils.

Subjective response testing 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 newborn babies; however, some infants do not demonstrate consistent fixation behavior until 2 months of age. Following movements in the first 2 months of life can be coarse and jerky and should not be expected to resemble the smooth pursuit movements of older children and adults.

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 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 and the ophthalmologist can play a pivotal role in making the timely diagnosis.

Ophthalmoscopic Examination

With undilated pupils, some information can be obtained by use of the ophthalmoscope in a dimly lighted room but ideally all newborns should be examined with an ophthalmoscope through dilated pupils. Ophthalmoscopic examination will demonstrate any corneal, lens, or vitreous opacities as well as abnormalities in the fundus. In premature infants, remnants of the tunica vasculosa lentis are frequently visible, either in front of the lens, behind the lens, or in both positions. The remnants are usually regressed by the time the infant has reached 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 called Mittendorf’s dot.

Physiologic cupping of the disk is usually not seen in premature infants and is rarely seen at term; if seen then, it is usually very slight. In such cases the optic disk will appear gray, resembling optic nerve atrophy. This relative pallor, however, gradually changes to the normal adult pink color at about 2 years of age. Preretinal and intraretinal hemorrhages have been reported in 30%–45% of newborns, usually clearing completely within a few weeks and leaving no permanent visual dysfunction.

Tests for Visual Acuity

In the early years, visual acuity should be assessed as part of each general “well child” examination. It is best not to wait until the child is old enough to respond to visual charts, since these may not furnish accurate information until school age.

During the first 3–4 years, estimations of vision rely greatly on observation and reports about the child’s behavior both at play and during interactions with parents and with other children. Unfortunately, at this age, seemingly normal visual performance is possible with relatively poor vision, and obviously abnormal performance probably reflects extremely poor acuity. The influence of visual impairment on motor and social development must always be borne in mind. The pupillary responses to light are 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 converging reflexes 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 occlusion of one eye strongly suggests it is the preferred eye, and therefore that the fellow eye must have comparatively poor vision. In cases of latent nystagmus—nystagmus increasing with occlusion of one eye—the child is likely to resent occlusion of each eye because of the effect such nystagmus has on visual acuity. Manifest nystagmus may be indicative of an anterior visual pathway disorder or other central nervous system disease until these have been excluded. (Further discussion of the assessment of nystagmus is given in Chapter 14.)

After 3 months of age, the presence of strabismus, detected by examining the relative position of the corneal light reflections, must also be regarded as indicative of poor vision in the deviated eye, particularly if this eye does not take up or is slow to take up fixation of a light upon occlusion of the fellow eye. (Further discussion of the assessment of strabismus is given in Chapter 12.)

These inferences about the status of the developing sensory systems can now be augmented 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 have gained increasing popularity as a reliable and relatively easy assessment of visual acuity in preverbal children, even in the very young. This technique does, however, have a tendency to overestimate visual acuity in amblyopes.

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 should prompt 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 most circumstances, cyclopentolate 1% drops applied twice—separated by an interval of 5 minutes—30 minutes prior to examination will provide sufficient cycloplegia, but atropine cycloplegia may be required if convergent strabismus is present or the eyes are heavily pigmented. Because atropine drops can be associated with systemic side effects, atropine 1% ophthalmic 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 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. About 10% have refractive errors that require correction 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. Anterior segment examination in the young child relies mainly on 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 anesthesia. Fundus examination relies on 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 and examination is often easily accomplished by allowing the infant to feed or nurse during the examination, at which time it is often possible to obtain intraocular pressure measurements as well as examine the eye thoroughly.

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 heavily pigmented 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 more heavily pigmented 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 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.

Corneal Abnormalities

Congenital opacification of the cornea may be partial or complete, and causes include 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