Gregg T. Lueder
The appropriate ocular history will vary depending on the reason the child has come for evaluation. If a child presents for a routine, well-child examination, the ocular history will be included in the review of systems. The caregiver should be asked about any specific eye complaints. In infants and younger children, the examiner’s questions should include whether the child appears to see normally, if there are any abnormal eye movements, or if there are any visible abnormalities of the eyes or periocular structures. Older children may be questioned directly regarding subjective symptoms, including blurred vision (difficulty seeing the blackboard at school or objects that friends or family members can see easily), double vision, or other concerns regarding vision or the appearance of the eyes.
If a child presents for evaluation of an ocular problem, the appropriate history will depend on the specific complaint. As with any medical concern, questions should include the onset and duration of symptoms, aggravating and alleviating factors, history of similar problems, and previous treatment.
General medical and family histories are also important in evaluating the eyes. Children who are born prematurely or who had perinatal difficulties have an increased risk of developing vision problems. Many systemic disorders, such as trisomy 21 and Marfan syndrome, are associated with specific ocular problems. Children with juvenile idiopathic arthritis are at increased risk for asymptomatic intraocular inflammation (uveitis) and therefore require longitudinal screening.1 Children with neurofibromatosis type 1 require annual examinations at least during the first 7 years of life to identify signs of optic pathway glioma. A family history of an ocular condition or systemic disease that affects the eye may also alert the examiner to look for specific problems. If family members have been affected by serious eye disorders that may be inherited, such as infantile cataracts, pediatric glaucoma, or retinoblastoma, screening by an ophthalmologist may be indicated, even if the office evaluation appears normal. More common familial problems include strabismus, myopia, and astigmatism.
When obtaining an ocular history, it is important to recognize that children may be unaware that they have a vision problem, even with significant visual impairment. Young children in particular typically adapt very well to decreased vision and often do not voice complaints, even when vision is below the level of legal blindness (worse than 20/200 in the better eye or severe visual field constriction). The visual demands of infants and toddlers are relatively minor—they only need to see well enough to find their food and toys and identify family members, and they do not need to read fine print. Therefore, they may appear to function quite well, often until grade 1 or 2, when visual demands begin to increase. In addition, children whose vision loss is confined to one eye also frequently do not voice complaints, even if specifically questioned. They function well with the vision in the normal eye and usually ignore the eye with the problem. This ability to unconsciously “ignore” one eye is the basis for the development of amblyopia. Even older children may be completely unaware of chronic unilateral vision impairment until the eyes are tested independently. For these reasons, the absence of vision complaints in children does not adequately rule out vision problems. The American Academy of Pediatrics recommends vision screening at every well-child visit.2 In addition to assessing vision, the pediatrician should be skilled at basic complete eye examination, to be used as time permits, as circumstances indicate, and as specific complaints or concerns may require.
Before children are old enough to read an eye chart, vision is assessed by watching the child fixate on objects, observing whether the eyes track smoothly and assessing whether the eyes move together equally. Although children with developmental delay or neurological abnormalities may be less attentive, more distractible, or difficult to engage, one should not assume that poor responsiveness to a visual target is due solely to the neurological condition. Consultation with an ophthalmologist may be needed to specifically assess the vision. The degree of interest the child has in these activities will be variable. Some children enjoy the examination, viewing it like a game, while others are apprehensive and have difficulty cooperating regardless of how nonthreatening the assessment may be. In addition, children’s level of interest may change depending on whether they are awake and alert or tired and irritable, and whether they are feeling well in general. If the child is uncooperative due to identifiable reasons that are likely to resolve and there are no vision or ocular concerns, it may be reasonable to defer the vision screening to a subsequent visit, but the pediatrician must be sure that this follow-up occurs.
It is useful to have brightly colored, interesting objects to hold in the examiner’s hand to monitor fixation and tracking. However, children may quickly become bored with a single toy, so it is useful to have a few toys that can be interchanged. In addition, it is helpful if the examiner can be flexible regarding the order in which the examination is performed. Looking at toys while sitting in their parent’s lap bothers few children, but they may begin crying or fighting if the examiner attempts to touch an area near their eyes. Therefore, it is best to perform the least invasive portions of the examination first, leaving the potentially more bothersome portions to the end. Although the specifics of the examination will be presented below, beginning with the front of the eyes and moving backward, the order may be adjusted to the child’s cooperation.
ASSESSMENT OF VISION
Although assessing vision may sometimes be difficult in young children, it is critically important to identify problems as early as possible. Vision matures rapidly in the first few years of life, and interruption of this process may produce irreversible loss of vision due to amblyopia. Severe problems, such as unilateral infantile cataracts, need to be corrected within the first few months of life if vision is to be restored. The prognosis for treatment of amblyopia due to strabismus or unequal refractive error is related to the age at which the problem is identified and treatment begun. The younger the child, the better the prognosis. However, it is also more difficult to assess vision in younger children.
The method of vision assessment varies with the patient’s age. Normal infants can fixate at birth, in particular on their mother’s face. This response is well recognized by parents feeding their child. Asking the parents of an infant, especially when they have previously raised a normal child, whether their child sees is a remarkably accurate assessment of the child’s vision. In the first 1 to 2 months of life, infants should at least respond to lights by blinking when a bright light is shone into the eyes. When the lights are turned off, the eyes often open, sometimes with the upper lids retracting such that the superior sclera (white of the eyes) becomes visible, a primitive response known as the eye-popping reflex. Many infants will track fairly well shortly after birth, but it is not abnormal to have minimal tracking at this early age. A 3-month-old infant should be able to fixate on a toy held in the examiner’s hand and should track the object back and forth as the examiner moves it. This is initially done with both eyes open. However, because an infant may track well if the vision is good in only one eye, it is important that the vision in the two eyes be assessed independently. This is done by covering each eye separately (usually with the examiner’s or caretaker’s hand) and monitoring whether the infant tracks equally well with either eye. If the child consistently tracks well with one eye covered but becomes upset or refuses to track when the opposite eye is covered, this strongly suggests that there is a vision problem in the first eye that was covered. An important caveat, however, is that some children get upset when either eye is covered, even if both eyes see well. Therefore, if the child becomes agitated equally with either eye covered, one may not be able to accurately judge the vision based on this behavior. In addition to distracting the child with interesting toys as vision stimuli, it is also important to try avoiding direct contact with the child’s face when occluding one eye. This can be achieved by placing the examiner’s hand slightly in front of, but not directly in contact with, one side of the face. Also, the examination should be conducted fairly quickly. If there is a difference in the visual responsiveness of one eye versus the other, it will often be readily apparent.
As children become older, usually by age 3 years, testing of vision with eye charts is possible. The child is placed a standard distance from a chart, the eyes are covered one at a time, and the child is asked to describe what they see. A variety of charts are available for use in the pediatric setting. In younger children, charts with readily identifiable symbols or pictures are usually most effective. The tumbling E test may also be used, but children may have more difficulty understanding this test, and before the age of 4 to 6 years, handedness may not be sufficiently developed to allow full compliance. Some children will be hesitant to vocalize what they see. Matching games or cards can be used, such as the HOTV test, that allow the child to point to a handheld card to match what they see, rather than speak out loud. By age 5 years, most children can read an adult eye chart with letters. Specific guidelines that include the details of how to perform these tests and the criteria for referral have been published by the American Academy of Pediatrics.2
Assessment of color vision may also be included in the ocular examination, but this is not required. Most children with color vision deficits function entirely normally and may not even realize they have a deficit until adulthood. Deficit in the red-green color system is an X-linked recessive disorder that is present in approximately 8% of males and 1% of females. It is important for families and teachers to be aware of this disorder so the etiology of an affected child’s inability to distinguish colors is properly identified. Tests such as the Ishihara test plates are used to screen for red-green color deficiency by having the individual identify colored numbers within different colored backgrounds. This test can normally be performed by age 5 to 6 years. If there is parental or teacher concern about color discrimination beyond this age, referral to an eye specialist may be indicated.
Binocular vision and depth perception may be affected by amblyopia, strabismus, and monocular visual impairment. However, children rarely experience significant functional problems due to these deficits. Formal testing usually requires consultation with an ophthalmologist. In particular, dyslexia and other reading problems are rarely due to ocular problems such as binocular vision or tracking difficulty. An ophthalmic examination is indicated in children with reading difficulties to rule out significant refractive errors or strabismus that could interfere with reading. In the absence of such problems, appropriate intervention includes remedial educational programs directed to reading strategies, rather than vision therapy, for which there is no scientific evidence of efficacy.3
EYELIDS, PERIOCULAR STRUCTURES, AND LACRIMAL SYSTEM
The eyelids in children should be symmetric, and the margin of both upper eyelids should rest above the pupil. If one or both eyelids droop (ptosis), children may adopt a chin-up head posture to view below the drooping eyelid(s), or they may contract the forehead frontalis muscles to assist in elevating the lid by raising the brow. Therefore, when evaluating eyelid height and function in a patient in whom ptosis is suspected, the examiner must be sure that the child’s head is in normal position and the frontalis muscles are not contracting. If the eyelid in an infant is covering most of the eye, particularly the pupil, prompt ophthalmologic evaluation is indicated because of the risk of permanent vision loss due to amblyopia.
The eyelid margins should be continuous and should rest against the globe, and the eyelashes should turn outward and not rub against the eye. The skin of the eyelid is very loose, and any condition that causes edema often manifests relatively early by swelling of the lids. Eyelid edema is usually most prominent upon awakening, due to the effects of gravity during sleep. This can be aggravated by vascular abnormalities such as port-wine stains. Likewise, following trauma or surgery, ecchymosis can accumulate quite extensively in the eyelids and may even make it difficult to open the eyelids.
Inflammation or masses in the eyelid or periocular structures should be noted. If an orbital mass or hemorrhage is present, patients may present with proptosis. In this condition, the entire eyeball is pushed forward and appears to bulge from the orbit. Widening of the space between the eyelids due to this bulging produces an asymmetric appearance, which is sometimes mistaken as ptosis of the normal eye. The proptotic eye appears more prominent and is often best assessed by looking down from above the patient (Fig. 580-1). The eye may be irritated due to corneal exposure and incomplete eyelid closure. Proptosis may be caused by several disorders and requires prompt evaluation by an ophthalmologist.
CONJUNCTIVA AND ANTERIOR SEGMENT
The conjunctiva and anterior segment are best examined with a penlight or the light from a direct ophthalmoscope. If a more detailed view is required, the examiner can look through the direct ophthalmoscope, adjusting the dial on the instrument to provide a focused, magnified view. If an infant or child is not anxious and the light is not too bright, this examination can be performed while the patient is sitting in the caretaker’s lap. If the eyelids are squeezed shut, they may need to be manually opened in order to perform the assessment. This can usually be done with the examiner’s fingers, but use of cotton-tipped swabs or an eyelid specula is sometimes necessary. The conjunctiva in newborns may have a yellowish tinge due to elevated bilirubin levels. Irritation of the conjunctiva may produce edema (chemosis). Chemosis is also seen after craniofacial surgery and in association with severe systemic edema. A red eye is due to infection of the conjunctival blood vessels. Smoke and chorine in swimming pools are common sources of irritation. Conjunctival swelling and infection associated with discharge are common manifestations of conjunctivitis. Conjunctival inflammation may also occur with marked increase in intraocular pressure (glaucoma) or iritis.
FIGURE 580-1. A view from above, sighting down over the forehead, may allow for greater appreciation of a proptotic eye, in this case the child’s right eye. Examination from a standard facial view will confirm that the appearance from above is not simply due to upper lid swelling.
Iris pigment is usually symmetric between the two eyes. Iris nevi are relatively common and present as flat, localized areas of increased pigmentation (Fig. 580-2). Asymmetric pupil color (heterochromia) may be seen in conditions such as congenital Horner syndrome and Waardenburg syndrome and following trauma. Proper differentiation of iris lesions usually requires evaluation with a slit lamp.4
RED REFLEX TEST
The best method for a pediatrician to assess the clarity of the lens, other anterior segment structures, and vitreous in a young child is to evaluate the red reflex.5 The red reflex test will also indicate the presence of anything in the eye that is white in color. The normal red reflex is usually not completely red. It may be orange, pink, or yellow-tinged. Normal variations also include crescents or other minor heterogeneity of the coloration. Most importantly, it should be the same in both eyes.
FIGURE 580-2. Iris nevus (asterisk). Note that the lesion is flat and that the iris architecture is largely preserved.
The red reflex is present in a normal patient due to reflection of a light shone directly into the eye from the red choroidal blood vessels under the transparent retina through the clear ocular structures. With the child seated on a caregiver’s lap, the direct ophthalmoscope can be held approximately 1 meter from the child and the lens adjusted to focus on the eyes. This is best performed in a dim room to increase pupil dilation. The examiner looks through the aperture of the ophthalmoscope and may do so with or without his or her glasses on. The child should not be wearing spectacles. The examiner should use the largest circle of white light from the ophthalmoscope and sit back far enough that both eyes are illuminated simultaneously.
A white reflex (leukocoria) may indicate a cataract or an intraocular tumor (usually retinoblastoma (Fig. 580-3). Pseudo-leukocoria sometimes occurs if the light is shone into the eye from a lateral direction, rather than straight on, and white light reflects off the optic nerve head. A black reflex may indicate ocular hemorrhage or some other reason that the light is blocked, such as a cataract (Fig. 580-4), but the most common reason is due to constriction of the pupil (miosis). Patients with abnormal red reflexes should be referred to an ophthalmologist promptly, and it is always better to refer if there is any concern about the examination. However, before referring a child with an absent red reflex, especially if bilateral, the pediatrician may prefer to instill eyedrops to dilate the pupils (phenylephrine 2.5% or cyclopentolate 1% after age 6 months) and recheck the red reflex 20 minutes later. If the red reflex is symmetric and normal after dilation, referral is not needed.
FIGURE 580-3. Leukocoria due to retinoblastoma in the left eye. The “red” reflex in the right eye is normal despite being a bit orange with a yellow-white crescent nasally.
The size of the pupil depends on a balance of forces between the dilating and constricting muscles in the pupil, which are controlled by sympathetic and parasympathetic inputs, respectively. Both pupils should be round and centered in the iris. Both should constrict when illumination is increased (either by shining a light directly into the eye, or by turning up the lights in the room). The two pupils should be of equal size, although up to 0.5 mm difference is present in approximately 20% of normal patients. Acquired versus congenital unequal pupils (anisocoria) can often be distinguished by examining old photographs. Trauma or inflammation (particularly iritis) may produce scarring and irregularity of the pupil margin or miosis.
FIGURE 580-4. Black-red reflex due to cataract in the child’s left eye. The right eye red reflex is normal despite being partially more yellow and partially more orange.
Pupil reactions are best checked by shining a penlight into each eye separately in a dim room. The two pupils should react equally to any light input. Even if a light is shone into one pupil only, both pupils will constrict in a normal individual. This phenomenon can be exploited to assess whether one visual pathway is damaged relative to the other (afferent pupillary defect also known as Marcus Gunn pupil).6
Eye movements are best evaluated by having children fixate on and follow small objects. This is done in conjunction with the visual assessment of preverbal children as discussed above. Older children may be asked to look in various directions to assess extraocular movements, but it is usually easiest to have them follow an object or the examiner’s finger or face. Eye movements should be symmetrical and full. In up and down gaze, the eye should move well behind the upper and lower lid, respectively, and should do so such that the edge of each iris that remains visible has moved symmetrically. Imagine a horizontal line being drawn from one eye to the other. This line should be parallel to the floor when aligned with the same point on each eye. With horizontal movement of the eyes, the white of the eye (sclera) should be “buried” and out of view. If the sclera does not bury in one eye on side gaze, cover the other eye and try again. If the sclera then disappears out of view, then one can be sure that the eye movements are full but that strabismus is present. In the straight-ahead viewing position, the examiner screens for strabismus using the Hirschberg light reflex test (see Chapter 586).
In the first few months of life, assessment of eye movements is difficult, because attention may be limited and the infant may not track objects consistently. In addition, at this early age, abnormal eye movements are relatively common. Brief episodes (a few seconds) of strabismus may occur in normal neonates. These usually subside by 2 to 3 months. However, if eye crossing persists beyond 3 to 4 months, if the child appears unable to move either eye outward normally, or if an infant has constant or prominent crossing, the child should be referred for further evaluation. Similarly, intermittent, very brief episodes of nystagmus may be seen in normal newborns in the first 1 to 2 months of life, but referral may be required if they are more noticeable, persistent, or not resolved by 3 to 4 months. After approximately 6 months of age, most infants will fixate and track well.
The visual fields represent the area in which lights or other visual stimuli are visible when the eyes are looking straight ahead (ie, peripheral vision). The degree to which these can be accurately measured depends on the age and cooperation level of the child. Visual fields in infants are assessed via evoked saccade testing. The examiner attracts the infant’s attention so the baby is looking at the examiner’s face or a toy held directly in front of the child. A penlight is then turned on in various peripheral positions (both sides, up, and down). If the child notes the light in their peripheral vision, he or she will turn the head and eyes to the light. This test cannot assess the visual fields with precision but verifies that they are at least grossly intact.
Confrontation testing can be performed in older children. In this method, the patient is asked to look at the examiner’s face. The examiner then holds up fingers in the patient’s peripheral vision and asks how many fingers the individual sees. Proper fixation is easily monitored by watching the patient’s eyes. The most precise and repeatable measurements are performed with formal visual field testing, which can be done only in older, cooperative children. This method uses computer-controlled lights and fixation monitoring to record fixation and accurately map the visual fields.
RETINA AND OPTIC NERVE
Examining the retina and optic nerve is often difficult in infants and young children. Challenges include the anxiety produced when the examiner comes close to the child’s face, small pupil size (which is usually made even smaller by the bright light of the ophthalmoscope), and the inability for young patients to hold their eyes still. Direct ophthalmoscopy is much more likely to be successful in older children but may be necessary in younger children, especially when there is a concern about intraocular abnormalities such as retinal hemorrhage or papilledema. If the pediatrician is unable to conduct adequate examination under such circumstances, consultation with an ophthalmologist is indicted. The ophthalmologist’s assessment is performed after pupillary dilation, using the indirect ophthalmoscope, which provides a wide-field, stereoscopic view of the retina and optic nerve.
Examination with the direct ophthalmoscope is facilitated if the room lights are dimmed, and the patient is asked to look at a distant object with the eye that is not being examined. The dim room light decreases pupillary constriction. Having the patient fixate on a distant object decreases accommodation, which also increases the pupil size. The examiner should use the smallest circle of light on the ophthalmoscope and make sure that the head does not block the view of the fixating eye. The examiner’s right eye is used to view the patient’s right eye, and vice versa for the left eye. The focus dial on the ophthalmoscope is used to bring the optic nerve into clear view, and the posterior retina and blood vessels can be examined by tracking along them with the light.