Ocular examination of a newborn, infant, or small child presents unique challenges that require special techniques and particular knowledge of the normal variations in eyeball anatomy and function of this age group. Children may be unable or unwilling to participate voluntarily in the examination. The ophthalmic assistant must also remember that the child’s caretaker is an integral part of the “patient team.” Attention to the needs of both parent and child is essential for obtaining the desired information.
Approach to parent and child
Children are unique patients in that they are almost always accompanied by a caretaker who is their advocate, communicator, and guardian. The parent must be enlisted as a positive participant in the child’s eye examination. In taking the ocular history, it is also important to distinguish between the parental concerns and the child’s symptoms that led to examination. Sometimes the parent may have observed a visual behavior that is of concern. In other situations, the parent may not have observed a problem that was noted by the referring pediatrician or family physician. One must never underestimate the value of parental observations, which should be noted on the patient’s chart even if they contradict the physician’s observation that initiated the referral. This is particularly important in assessing a baby who is thought to have poor vision or blindness. The question should be, “Do you think your baby sees?” Although some parents may deny that their baby’s sight is poor, most will make an accurate assessment of the baby’s ability to see objects and people, in particular the face of the parent during feeding. The parental assessment provides a most valuable piece of information.
Although it is important for ophthalmic assistants to introduce themselves to the parents, a self-introduction directly to the small child is also recommended. The child’s individuality must be recognized and honored. Young children need to know that they have some control over the examination environment. They are often scared, unsure, or even tearful and combative. The initial introduction and conversation with the child may determine the success or failure of the remainder of the examination. Before conversing with the parents, the assistant can chat with the child about issues unrelated to the visit, inquiring about the youngster’s age, siblings, pets, or a toy the child is clutching. Ask what game the child is playing on his or her tablet or smart phone and have the child demonstrate. Notice what is on the child’s T-shirt, unusual jewelry, or a book he or she may be reading. If a teenager looks bored or unhappy, try to break the ice with some humor about the teen not wanting to be there. These comments often provide valuable reassurance to the child that the examiner has true interest and concern for the child’s wellbeing. It is usually harmless to allow younger children to gain some feeling of control over this unfamiliar environment by asking if they want to sit alone or on the lap of a particular parent, allowing them to explore the room and touch equipment, and allowing them to play with toys or siblings in the room while the interview with the parent proceeds. It is essential for the ophthalmic assistant to have several toys available to distract the younger child both before and during the examination.
The assistant can make the examination a game by constantly carrying on a playful banter while presenting the child with tasks and toys. Banter about more mature matters, such as sports, dating, and extracurricular activities can even keep the teenager engaged. For younger and more fearful children, it is important to glean as much information as possible without touching the child. Often one can assess eye movements, pupillary reactions, external ocular anatomy, and even visual acuity with only the most minimal physical contact. When the child is asked to answer questions or perform visual tasks, such as visual acuity testing or binocular vision testing, one should always be positive when responding to the child’s answer even if that answer is incorrect. If the child makes a mistake, one can simply say “good job” and move on to the next letter. Undermining a child’s confidence by indicating a poor performance on a visual test may decrease compliance with the examination. It is also helpful if the examination is conducted without external interruptions, such as answering telephone calls or the movement of people walking in and out of the room. Because children in the younger age groups or older children with developmental challenges have very short attention spans, the examination must be conducted swiftly, in good humor, and with minimal extraneous distractions.
If the child becomes tearful or uncooperative, it often is best to back off and either undertake an unrelated conversation or ask the child how he or she would like to proceed. For example, some children prefer to hold the penlight or direct ophthalmoscope themselves. They can hold the instrument along with the assistant who is conducting the examination. It may be helpful to perform part of the examination on the parents or the child’s toy (e.g., a teddy bear) in a mock fashion to demonstrate that it is painless before carrying out that step of the examination on the child.
Children have certain biologic needs that must be satisfied if an optimum examination is to be completed. If an infant appears cranky, one might inquire if the parent believes that the child needs to feed. Quite a bit of information can be obtained while the child is being examined during a feeding. A pacifier or favorite toy also should be allowed because it may increase the child’s level of comfort and security. Interruptions for diaper changes and visits to the washroom must be permitted. If a sibling’s behavior is distracting, the examiner can turn attention to that child and invite him or her to participate in the examination. For example, a sibling can be asked to flip the switch when the lights are being turned on and off or to hand the examiner toys and tools that are being used.
Assessment of the visual acuity in neonates and infants is often limited to ascertaining whether vision is absent, present, or within normal limits for their age and equal in both eyes. Visual fixation is present at birth. The best visual target for the neonate is the human face. Normal infants should smile responsively and briefly follow a stimulus by 2 months of age. In the second and third months of life, infants develop the ability to follow a target beyond the midline, although it may not be until the fourth month that they can follow completely from one side over to the other (180 degrees). When the examiner presents an infant with a target, it is important to use a silent toy to ensure that any following or responsive behavior that is observed results from visual rather than auditory stimuli. High-contrast (black and white) targets are particularly helpful.
Children who are blind or have very poor sight often have wandering, purposeless, dysconjugate eye movements or nystagmus. The presence of nystagmus at birth, however, does not necessarily imply complete blindness. If a child has very poor sight, it is important to note if there is a response to light (light perception [LP]). One can look for the “eye-popping reflex” by abruptly turning off all illumination in the room. A sighted baby or infant will demonstrate a reflex opening of the eyes. When the lights are then turned on abruptly, both eyes should close. Even premature babies should respond to a bright light. If the child’s eyes are closed, the bright light can be shone through the closed eyelid and a reflex contraction of the eyelid and surrounding muscles should be seen.
More formal technical tests are available to better quantify an infant’s visual acuity, such as preferential-looking tests, and graded optokinetic nystagmus (OKN). The visual evoked potential (VEP) is a test designed to measure the ability of the occipital cortex in the brain to register a response to visual targets of increasingly difficult resolution by placing electrodes on the scalp that sense the passage of visual information from the eyeballs to the brain. The OKN drum ( Fig. 28.1 ) will elicit nystagmus in anyone capable of seeing the stripes on the rotating drum. Preferential-looking techniques ( Fig. 28.2 ) rely on the ability of an infant to distinguish between and favor a target that is variably different in terms of resolution (e.g., black-and-white stripes) compared with a bland gray target. The electroretinogram (ERG) is used to assess whether the retina is functioning in a child who is apparently blind or has poor sight. This test does not, however, measure visual acuity.
If a significant difference exists in the visual acuity between the two eyes, the small child will object to the examiner covering the better eye. Although the eye can be covered by a piece of tape, the examiner’s hand, or a commercially available occluder paddle, just using one thumb may be less frightening ( Fig. 28.3 ). The child may become visibly uncomfortable or may attempt to remove the obstruction only when the better-seeing eye is covered. This test is best performed while presenting the child with a target of interest, such as a bright toy. A differential response on the covering of either eye is a critical sign of a difference in vision between the eyes.
The visual acuity in infants and preverbal children is usually recorded as central steady maintained (CSM) or good steady maintained (GSM). This indicates that the eyeball fixates with the fovea straight along the visual axis, nystagmus does not occur in the straight-ahead position, and there is no preference for either eye. If an eye is clearly unpreferred (i.e., not seeing as well as the other eye), but is otherwise straight and steady when it is fixating a target, the examiner may record the child’s vision as CSNM: central, steady, but not maintained. Vision is not central when the patient appears to be fixating on a target although the eyeball is not pointing directly at what is being presented (eccentric fixation).
As children approach 3 to 5 years of age, they begin to be able to participate more voluntarily in the assessment of their visual acuity. Several types of charts that can be projected or posted for use in more formal visual acuity testing are listed in Box 28.1 . The method chosen must be consistent with the child’s developmental level and skills. For example, projected pictures (Allen pictures, Fig. 28.4 ) are a good test for a child who does not yet know letters. One might show the pictures to the child up close and ask that the figures be identified so that the examiner is aware of what interpretation the child gives to these somewhat abstract diagrams. For example, the birthday cake may be called a “bag of french fries” and the telephone a “butterfly.” As long as the examiner knows what the child calls that picture, testing can proceed. At distance, even normally sighted children may have difficulty seeing pictures smaller than the 20/80 line.
HOTV matching test
Allen picture test
Snellen letter chart
Tumbling E chart (not recommended, see text)
The use of recognition letter charts (Snellen letters) should be reserved for those children whose ability to identify letters is verified in advance by the parent. For children in the intermediate stage in which they recognize some of their letters, the Sheridan-Gardiner (Keeler, London, England) and HOTV tests may be helpful because they allow the child to match letter cards held by the examiner or projected letters with a cue card the child holds ( Fig. 28.5 ). This approach also gives shy children more confidence and allows them to guess letters they might otherwise not feel secure enough to guess at orally. Children in these young age groups are often afraid of being wrong and, even with the greatest encouragement, will not read letters that they really are able to see. This underscores the constant need for building the child’s confidence by indicating that the answer given is correct even when it is not. The tumbling E chart also can be used for children who do not recognize their letters. This test can, however, be difficult for small children to interpret because they may not know left from right and they may have trouble indicating with their hands in which direction the tumbling E is pointing, particularly when they are younger than 4 to 6 years old, the age range when handedness normally develops. At this age, they are almost always able to use other methods, rendering the tumbling E unnecessary.
When the visual acuity is tested, one eye must be covered at a time. Children will unconsciously make every effort to use their better eye if there is a difference between the visual acuity in their two eyes. Therefore the occlusion of one eye must be absolute. Children should never be allowed to hold their hand over their eye or to handhold a plastic occluder paddle. They may look around the occluder or look through tiny holes between their fingers, which can actually create a pinhole effect and improve the vision in the covered eye. It is recommended that 2-inch (5-cm) paper tape be applied over the eye that is not being tested to effect complete occlusion. Children must be observed constantly throughout the visual acuity examination to be sure that they are not peeking between the tape and their skin ( Fig. 28.6 ). This can be accomplished either by the use of a “cheater’s mirror” placed behind the child, which allows the examiner to view the projected target behind them while still facing the child, or by having the examiner stand next to the chart at the end of the examination lane while viewing the child and indicating which letters are to be read. If a child objects to the covering of one eye by tape, the examiner can hold a +5.00 or greater spherical lens in front of the eye not being tested. In most children, this sufficiently blurs that eye so that the child is actually viewing with the eye that does not have a lens in front of it even though both eyes are open. Having the parent use a hand to cover the child’s eye invites the same problems as having the eye covered by the child’s hand. If there is no other option, make sure the parent uses their palm rather than fingers to occlude the eye. If the child completely resists any form of intervention, ask him or her to read the chart with both eyes open and record the binocular vision.