An examination of the eyes should be part of every well-child visit. In most cases the children and parents will have no concerns, and the evaluation will consist of screening questions and a brief physical examination of the eyes. In some instances, the child or parents may express specific concerns about vision or the appearance of the eyes. In these cases, a focused history and a more detailed physical examination will be indicated.
- The first section describes the important aspects of the medical history for children with ocular problems.
- The second section describes a quick screening examination for eye problems that can be performed during well-child evaluations in the pediatric office.
- The third section describes additional examination techniques that pediatricians can use for evaluation of children with specific ocular problems.
- The fourth section describes the examination techniques and tools used by pediatric ophthalmologists.
As with any well-child examination, basic questions about the child’s general medical history should be asked. This is part of the routine evaluation of new patients, and the information will already be known for established patients. General questions about vision and the eyes should be included in well-child visits, whereas additional questions may be indicated if specific problems are identified. A family history and review of systems are also important components of the evaluation.
The pediatric history should include questions about the pregnancy and birth. Prenatal exposure to infectious diseases or teratogens may cause specific ocular problems. The parent’s reports of the child’s general health and development should be obtained. Vision problems may occur in many pediatric systemic diseases. In some diseases, specific ocular abnormalities are present. In many systemic disorders associated with developmental delay, however, the ocular problems are nonspecific. Delayed visual tracking and strabismus are common features of global developmental delay from many causes (Table 1–1). The appropriate evaluation is influenced by this information. For instance, it will take longer for an infant born at 28 weeks gestation to begin tracking consistently than it will for a full-term infant. Therefore, additional investigations might not be indicated unless a tracking problem in a pre-term infant persists beyond the first few months of life.
General questions about vision should be part of every well-child evaluation. This may be as simple asking the parents whether they have any specific concerns about their child’s vision and whether they feel their child sees well. Additional questions could address whether the eyes track normally and whether there are any concerns about the appearance of the eyes or periocular structures. If specific problems are identified by the parents or noted during examination, more specific questions will be indicated.
The appropriate history for ocular problems follows the same principles as those for any other medical problem. These include questions about timing, duration, exacerbating factors, and previous treatments:
- When was the problem first noted?
- How frequently does it occur?
- Is it getting worse?
- Does anything seem to make it better or worse?
- Have you tried any treatments?
The specific questions themselves will depend on the nature of the ocular problem being evaluated. These are addressed in more detail in the sections of the book that deal with the evaluation and initial management of specific ocular problems.
In addition to specific eye-related questions, the review of systems in children with ocular complaints should include questions about the child’s neurological status (e.g., whether the patient has had any headaches, nausea, vomiting, change in behavior, clumsiness, etc.) Additional review of systems may be indicated in certain situations. For instance, a child with new onset of iritis should be questioned about symptoms of arthritis (due to the association of iritis with juvenile idiopathic arthritis). These specific questions are addressed in their respective chapters in the book.
Many ocular problems have genetic components, and the family history is useful in their assessment. In addition to specific medical information, the number of siblings a patient has is important when asking questions about the patient’s eye problem. If a child has older siblings, the parents will have a better understanding of the development of normal visual behavior than if the patient is the only child.
- With any family history, the larger the number of siblings and first-degree relatives the more informative the family history will be, particularly with regard to inherited diseases. For example, if an autosomal recessive disorder is being considered, the risk to each child is 1 in 4. Therefore, the absence of disease in several siblings would be informative, whereas it would be much less helpful if there were only one sibling (unless that sibling was affected with the same disorder). Similarly, questions about male relatives on the maternal side may assist in evaluating potential X-linked disorders.
Many systemic and ocular disorders are inherited in a mendelian fashion (autosomal dominant, autosomal recessive, and X-linked). Specific questions about these should be asked, based on the diagnoses being considered. Other ocular problems, particularly strabismus, are multifactorial. They have a genetic component, but are not linked to specific genetic mutations. This information may be particularly useful in assessing a child with the new onset of strabismus. If the child has several relatives with strabismus, there will be less concern that a central nervous system tumor or other underlying problem is causing the problem.
A routine eye screening examination should include an assessment of vision, eye movements, structural abnormalities, and the red reflex. The methods to assess these are based on age.
Because infants and young children are not able to comprehend or comply with visual acuity testing, the assessment of vision is primarily based on the child’s behavioral responses. The initial assessment is made by simply noting whether the infant responds to the examiner’s face. A toy or interesting object is then held in front of the child and the examiner monitors the infant’s behavior (Figure 1–1).
A normal visual response requires the following: the child’s eye must be able to see the object. The eye then sends visual information to the occipital cortex, where it is processed. This information is then sent to other areas of the brain that stimulate a behavioral response. If a toy is held in front of a child and the child reaches for it, this indicates that the child must have seen the ball. The test is performed with both eyes open, then with each eye individually (by occluding the opposite eye with a hand or some other object).
A normal behavioral visual response indicates that the child does not have a profound visual problem, but there are several caveats:
- It does not rule out a moderate problem. This is because most young children adapt to and function well with visual problems, such that their behavior may make it appear that the vision is better than it is.
- It is important that the toy not make a noise and that the examiner be quiet while performing this test. Children may be attracted to noise, and this could be erroneously interpreted as a visual response.
- When testing the eyes individually, the visual responses should be similar. Some children reflexively object to having their eyes covered. It is important to determine whether this is due to decreased vision, or simply an aversion to something coming near them. If the child always responds negatively with one eye covered, but tracks well with the other, then the vision is probably decreased in the eye that the child does not track with (Figure 1–2A–C). However, if the child reacts equally negatively to either eye being covered, then little information can be gleaned from the test (Figure 1–3).
FIGURE 1–2
Behavioral evidence of decreased vision in right eye. (A) A small toy is used to get the child’s attention, and the examiner covers the right eye to monitor fixation of the left eye. The child fixates on the toy without objecting. (B) When the left eye is covered, the child objects and tries to move the examiner’s hand. (C) When the right eye is covered, the child does not object and tracks the object.
During the same portion of the examination, the eye movements should be assessed. The toy is moved from side to side and up and down and the child’s tracking is monitored. The eyes should move symmetrically horizontally and vertically and there should be no limitation of movement. The presence of nystagmus can also be noted at this time.
There are 2 main methods for assessing strabismus. The first (the corneal light reflex test) is a quick screening tool. The second (cover testing) is used when there is concern that the patient might have strabismus.
This is a quick and effective screening test. The light from a penlight or other handheld light is held in front of the child. Most children will find this interesting and look toward the light. In normal patients, the reflex from the light will fall on the same spot in each cornea. If the patient is esotropic, the reflex on the in-turned eye will be displaced temporally. In exotropia, it will be displaced medially (Figure 1–4). This test is particularly useful in assessing pseudostrabismus, in which the patient appears esotropic due to epicanthal folds, but the light reflex test shows that the eyes are straight. The light reflex can be used to estimate the degree of strabismus, based on how far the reflex is deviated from a central position.
FIGURE 1–4
The corneal light reflex test, used to screen for strabismus. When the eyes are straight (middle figure), the corneal light reflex is centered on both corneas. If the patient is exotropic, the light reflex is displaced medially; if the eye is esotropic, the light reflex is displaced temporally (arrows).
In certain conditions, the eyes may be optically straight, but the corneal reflexes are not symmetric. A frequent type of this form of pseudostrabismus is called positive angle kappa, in which the light reflex makes it appear that the patient has exotropia. This most commonly occurs in patients who have retinopathy of prematurity that causes the fovea (responsible for central vision) to be dragged temporally. The eye, therefore, must be in an outward position to align the fovea with the visual axis (Figure 1–5). These patients do not demonstrate a shift when checked with the alternate cover test (described in the following sections) (Figure 1–6A–C).
FIGURE 1–6
Pseudoexotropia due to positive angle kappa. (A) The left eye appears exotropic because the corneal light reflex is decentered nasally and more sclera is visible nasally in the left eye compared to the right. However, neither the eyes nor the corneal reflexes shift when either the (B) right eye or the (C) left eye is covered, indicating that the patient has pseudostrabismus.
This test is not always necessary during routine screening, but should be attempted if there is a concern about strabismus. In patients with normal vision, both eyes look at an object at the same time. Therefore, if one eye is occluded, the opposite eye should not move. In patients with strabismus one eye is deviated. In children the vision from this eye is usually ignored, and the patient is not aware that the eye is not being used. If the straight eye is covered, the other eye will make a movement to line up the visual target. If a patient is exotropic, the eye will make an inward movement. If an eye is esotropic, it will make an outward movement (Figure 1–7).
FIGURE 1–7
The cover test for strabismus. Top: The patient has a right exotropia. Middle: When the left eye is covered, the right eye moves inward to fixate, which causes the left eye to move outward behind the cover. Bottom: When the cover is removed, the patient reverts to fixating with the left eye, causing both eyes to move to the right.
There are 2 caveats to this test:
- Similar to what may occur when covering an eye to assess vision, some young children will object to having anything held in front of their eyes. Some of these children may settle down and allow testing with time, particularly if the toy used for a target is changed frequently to maintain the child’s interest. In others, repeated attempts are unsuccessful, in which case the test cannot be performed.
- Many normal people have a phoria. This is a tendency for the eyes to drift if binocular vision is interrupted. In these patients, the eye moves slightly after it is covered. When it is uncovered, it makes a movement to return to normal. A phoria is present if there is no movement of an eye when the opposite eye is initially covered, but the eye begins to drift if the cover is left in place. Therefore, in a screening examination the examiner should look for movement of the uncovered eye when the opposite eye is initially occluded, rather than looking at the occluded eye after the occluder is removed. This is discussed further in the section on the ophthalmologist’s examination later in this chapter.
Cataracts and retinoblastoma are rare in childhood, but it is very important that they be diagnosed as early as possible. They most commonly present as abnormalities of the red reflex. This can be easily assessed using a direct ophthalmoscope from 2 to 3 ft away from the patient in a darkened room. The infant will usually be interested in the light and look directly toward it. The focusing dial on the ophthalmoscope should be adjusted so the child’s face is in focus. As the child looks at the light, the red reflex from both eyes should be symmetric (Figure 1–8A–C). If one eye appears white, this suggests the child may have a cataract or intraocular tumor.
FIGURE 1–8
Red reflex testing with the direct ophthalmoscope, which also screens for strabismus and pupil symmetry. (A) The examiner sits about 3 ft away from the patient. The dial on the ophthalmoscope (arrow) is used to focus on the patient’s face. The patient sits comfortably in her parent’s lap. (B) If needed, a small toy can be placed on top of the ophthalmoscope to get the child’s attention. (C) Red reflex results. This patient has esotropia of the left eye (note the lateral displacement of the left corneal light reflex compared to the centered reflex on the right [arrows]). The red reflexes are otherwise normal, without sign of a cataract or retinoblastoma.
An advantage of this technique is that the symmetry of the corneal light reflex can be assessed at the same time, which provides a quick screen for strabismus, and the pupils can be evaluated for symmetry.
For practical purposes, most parents will bring to your attention any concerns regarding visible abnormalities of the eyeball, eyelids, or orbit. Nevertheless, a brief inspection should be part of routine screening.
By ages 4 to 5 years, most children will be able to cooperate with visual acuity testing (American Academy of Pediatrics Committee on Practice and Ambulatory Medicine and Section on Ophthalmology. Pediatrics. 2003;111:902–907). This is most commonly done using a wall chart at a standard distance. Charts are available for young children that have drawings of figures, rather than letters. Most school-aged children can cooperate for standard testing with Snellen letters.
Vision is measured by a ratio comparing what the patient sees at a standard distance compared to what a normal patient can see. Normal vision is 20/20, meaning the patient can read an object from 20 ft away that normal individuals can also read. The ratio is greater than 1 if patients see better than normal (e.g., 20/15 vision means the patient can identify a letter from 20 ft away that normal individuals can only see from 15 ft). The ratio is less than 1 if the vision is worse than normal (e.g., a patient with 20/40 vision must be 20 ft away from a letter to identify it, compared to normal individuals, who can see the letter from 40 ft away). In countries that use the metric system normal vision is often notated as 6/6 (using 6 m instead of 20 ft as the standard testing distance).
| A good well-child screening eye examination in a toddler can be performed efficiently by rapidly checking the vision and red reflex. It is usually best to check the red reflex with the direct ophthalmoscope first because this is less likely to disturb the child (because the test is performed without coming near the patient). If the red reflexes are normal and symmetric, the vision can then be checked quickly. The examiner holds up a small object and covers each eye independently to see whether the child fixates and follows. If this occurs equally well with both eyes, the vision can be assumed to be equal or nearly equal (Table 1–2). |
| • Check red reflex with direct ophthalmoscope |
| • At the same time, check light reflex on cornea to screen for strabismus |
| • At the same time, check pupils for symmetry |
| • Assess vision by infant’s fixation behavior |
| • At the same time, check eye movements |
| • Assess for any obvious abnormalities of the eye, eyelid, and orbit |
Before age 5, vision of 20/40 or better is considered normal. After age 5, vision should be 20/30 or better. A difference between the two eyes of one line is normal. A difference of 2 lines or greater, even if both eyes are in the normal range (e.g., one eye 20/20 and the other 20/30), is abnormal (Table 1–3). Children who fail the screenings should be referred to an optometrist or ophthalmologist for further evaluation.
A quick screening for eye movements, strabismus, and examination of the red reflex should be performed using the same techniques described above.
A number of different machines have been developed to facilitate vision screening by pediatricians and lay personnel. There are two basic types:
- Photoscreening machines are based on evaluation of the red reflex (the same reflex that can be seen in photographs). The test can screen for 3 potentially amblyogenic conditions: (1) opacities of the red reflex could indicate a cataract, tumor, or other lesion, (2) asymmetry of the cornea light reflex could indicate strabismus, and (3) abnormalities of the light reflected through the pupil can be analyzed to estimate the refractive error. The advantage of photoscreeners is that the two eyes are examined simultaneously and all 3 of these factors are assessed.
- Autorefractors assess vision by estimating the refractive error of each eye independently, using analysis of the light reflection. They are generally less expensive and easier to use than photoscreeners, but they do not screen for strabismus and are less effective at screening for red reflex opacities.
Additional tests beyond those used for routine screening discussed may be indicated, based on concerns raised by the parents or by identification of possible problems during the examination.
If the two eyes work together, patients normally will have depth perception (the ability to perceive where objects are in space). This can be measured in the office by using polarized glasses and stereoscopic targets. These tests are similar to those used when viewing a 3-D movie. Some tests have pictures in which a portion of the object appears to stick up from the page when viewed through the glasses (Figure 1–9A and B). Random dot stereograms have no discernible objects when viewed without polarized glasses, but figures are visible when the glasses are used (Figure 1–10A and B).
