Children in this age group (birth to 2 years, 11 months of age) generally perform best if the examination takes place when they are alert. Examination early in the morning or after an infant's nap is usually most effective. Because infants tend to be more cooperative and alert when feeding, it is also helpful to suggest that the parent bring a bottle for the child.
Age-appropriate examination and management strategies should be used. Major modifications include relying more on objective examination procedures and performing tests considerably more rapidly than with older children.
Early detection and treatment are essential to preventing vision conditions that have the potential to cause permanent loss of vision. Screening by the pediatrician or other primary care physician is important at birth and during the first 6 months of life when the visual system is highly susceptible to interference. However, screening this population has been problematic, leading to underdetection of strabismus, amblyopia, and significant refractive error. Newer screening techniques such as photorefraction are available, but until they are validated, an eye and vision examination at 6 months of age is the best approach for early detection and prevention of eye and vision problems in infants and toddlers (see Table 3 in the original guideline document).
The eye and vision examination of the infant or toddler may include, but is not limited to, the following procedures (see Appendix Figure 2 in the original guideline document):
- Patient History
A comprehensive patient history for infants and toddlers may include:
- Nature of the presenting problem, including chief complaint
- Visual and ocular history
- General health history, including prenatal, perinatal, and postnatal history and review of systems
- Family eye and medical histories
- Developmental history of the child
The collection of demographic data generally precedes the taking of the patient history. Having the parent(s) fill out a questionnaire facilitates obtaining the patient history. Responses to questions related to the mother's pregnancy, birth of the child, and the child's general and vision development will help direct the remainder of the examination.
- Visual Acuity
Assessment of visual acuity for infants and toddlers may include these procedures:
- Fixation preference tests
- Preferential looking visual acuity test
See the original guideline document for a full discussion of these tests.
If clinical evaluation of an infant or toddler by indirect visual acuity testing, refraction, and ocular health assessment indicates any problem with visual acuity, forced-choice preferential looking with the Teller acuity cards or electrodiagnostic testing should be considered to obtain a more precise measure of baseline visual acuity. Consultation with an optometrist or ophthalmologist who has advanced clinical training or experience with preferential looking assessment or electrophysiological evaluation of visual acuity may be warranted.
- Refraction
Traditional subjective procedures for the assessment of refractive error may be ineffective with infants or toddlers because of short attention span and poor fixation. As a result, the examiner will need to rely on objective measures of refraction. The two most commonly used procedures are:
- Cycloplegic retinoscopy
- Near retinoscopy
It is important for the examiner performing cycloplegic retinoscopy in an infant or toddler to take several precautions:
- Select the cycloplegic agent carefully (e.g., fair-skinned children with blue eyes may exhibit an increased response to drugs and darkly pigmented children may require more frequent or stronger dosages).
- Avoid overdosage (e.g., children with Down syndrome, cerebral palsy, trisomy 13 and 18, and other central nervous system disorders in whom there may be an increased reaction to cycloplegic agents, 1% tropicamide may be used).
- Be aware of biologic variations in children (e.g., low weight infants may require a modified dosage).
Cyclopentolate hydrochloride is the cycloplegic agent of choice. One drop should be instilled twice, 5 minutes apart, in each eye, using a strength of 0.5% for children from birth to 1 year and 1% for older children. (Note: Every effort has been made to ensure that drug dosage recommendations are accurate at the time of publication of this Guideline. However, treatment recommendations change due to continuing research and clinical experience, and clinicians should verify drug dosage schedules with product information sheets.) Spray administration of the drug appears to be a viable alternative to the use of conventional eye drops for routine cycloplegic retinoscopy in the pediatric population. The child is asked to keep his or her eyes gently closed while the examiner sprays the cycloplegic agent on the child's eyelids. As the child blinks, enough of the drug is delivered to the eye to provide adequate cycloplegia. This technique has two advantages: (1) The child has less of an avoidance response, and it may be less traumatic for the child and the parent observing the procedure. (2) A single application can achieve both cycloplegia and pupillary dilation when a mixture of 0.5% cyclopentolate, 0.5% tropicamide, and 2.5% phenylephrine is used. To maintain sterility, it is best to have this spray mixture prepared by a pharmacist. Retinoscopy may be performed 20-30 minutes after instillation. The use of loose lenses or a lens rack is recommended for retinoscopy.
A study comparing retinoscopy in infants using near retinoscopy, cycloplegia with tropicamide 1%, and cycloplegia with cyclopentolate 1% found that tropicamide may be a useful alternative in many healthy, nonstrabismic infants.
Near retinoscopy is another objective method of estimating refractive error in infants and toddlers. However, it has not been found reliable for quantification of the refractive error.
Near retinoscopy may have some clinical value in the following situations:
- When frequent followup is necessary
- When the child is extremely anxious about instillation of cycloplegic agents
- When the child has had or is at risk for an adverse reaction to cyclopentolate or tropicamide
The average refractive error in children from birth to 1 year of age is about 2 diopters (D) of hyperopia (standard deviation 2 D). Astigmatism up to 2 D is common in children under 3 years of age. Studies show that 30-50 percent of infants less than 12 months of age have significant astigmatism, which declines over the first few years of life, becoming stable by approximately 2½ to 5 years of age. Low amounts of anisometropia are common and variable in infants. The clinician may choose to monitor these levels of refractive error rather than prescribe a lens correction.
- Binocular Vision and Ocular Motility
The following procedures are useful for assessing binocular function:
- Cover test
- Hirschberg test
- Krimsky test
- Brückner test
- Versions
- Near point of convergence
The cover test is the procedure of choice for evaluation of binocular vision in preverbal children because it is objective and requires little time to administer. If the cover test results are unreliable because of the child's resistance to testing, other methods may be used. In such cases, use of the Hirschberg test is often successful in infants 6 months and younger. Prisms can be used with the Hirschberg test to align the corneal reflections (Krimsky test) and determine the magnitude of the deviation.
The Brückner test is another means of objectively assessing binocular vision, as well as providing an indirect evaluation of refractive error. When both eyes are simultaneously illuminated with the ophthalmoscope beam at a distance of 100 cm, an overall whitening of the red reflex across the entire pupil of one eye indicates strabismus or anisometropic amblyopia. While the absence of a Brückner reflex is not a good indication of alignment, the presence of a Brückner reflex is considered a positive result, and is a good indication of strabismus, even of small amounts. Once detected with the Brückner reflex, the deviation should be quantified with the cover test or Krimsky technique.
Additional binocular testing often can be performed successfully with infants and toddlers. For example, preferential looking techniques can be used to assess stereopsis with some success.
Assessment of extraocular muscle function and concomitancy may involve version testing with an appropriate target. If the infant will follow a penlight, observation of the corneal reflections in all cardinal positions of gaze is possible. When a problem is suspected, the cover test procedure should be used for the position of gaze in question. After performing version testing, the clinician may find it useful to move the penlight or other target toward the child to assess objectively the near point of convergence (NPC).
If a binocular vision disorder or an ocular motility problem is suspected, consultation with an optometrist or ophthalmologist who has advanced clinical training or experience with this population may be warranted.
- Ocular Health Assessment and Systemic Health Screening
An evaluation of ocular health may include:
- Evaluation of the ocular anterior segment and adnexa
- Evaluation of the ocular posterior segment
- Assessment of pupillary responses
- Visual field screening (confrontation)
The diagnosis of eye disease in infants and toddlers presents some unique challenges. Standard procedures such as biomicroscopy, tonometry, and binocular indirect ophthalmoscopy are considerably more difficult in this population.
The cover test and versions, both important binocular vision assessment procedures, are also important for ocular health assessment. For example, the presence of strabismus may indicate any number of disease entities such as neoplasm, neuromuscular disorder, infection, vascular anomaly, or traumatic damage.
The examiner performing external ocular evaluation should gather as much information as possible by gross inspection of the eyes and adnexa. Generally, children up to the age of 6-9 months are sufficiently attracted to lights to permit adequate evaluation using a penlight or transilluminator. With the older infant, it is important to use a variety of interesting targets that can be attached to the transilluminator. Pupil function (direct, consensual, and afferent pupil integrity) should also be evaluated.
A hand-held biomicroscope may be used for evaluation of the anterior segment or the parent/caregiver may be able to position and hold the infant or toddler in a standard biomicroscope. If a corneal problem is suspected, but use of the biomicroscope is impossible, the optometrist may attempt an examination using sodium fluorescein and a Burton lamp. Another simple alternative is to use a self-illuminated, hand-held magnifying lens, or a 20 D condensing lens with a light source.
Thorough evaluation of the ocular media and the posterior segment generally requires pupillary dilation. Recommended drugs and dosages for pupillary dilation in infants and toddlers are one drop each of tropicamide (0.5%) or cyclopentolate (0.5%) and one drop of phenylephrine (2.5%). The spray mixture discussed previously is effective in achieving both dilation and cycloplegia in the pediatric population. Both direct and binocular indirect ophthalmoscopy may be performed after the pupil has dilated. An ideal time for evaluation of the posterior segment is when the infant is in a calm, relaxed, sedated condition (i.e., being bottle fed or sound asleep). When adequate fundus examination is impossible but is indicated by patient history, examination under sedation or anesthesia may be warranted.
Measuring intraocular pressure (IOP) is not a routine part of the eye examination of the infant or toddler. Although it is extremely rare in this age group, glaucoma may be suspected in the presence of a number of signs (e.g., corneal edema, increased corneal diameter, tearing, and myopia). Measurement of IOP is difficult and the results often are unreliable. However, pressure should be assessed when ocular signs and symptoms or risk factors for glaucoma exist. Measurement of IOP in the pediatric population may be accomplished with hand-held applanation and noncontact tonometers. If risk factors are present and reliable assessment of IOP under standard clinical conditions is impossible, testing under sedation may be appropriate.
When strabismus or other neurological problems are suspected, confrontation visual fields should be attempted with infants and toddlers using a variation of the traditional approach. A shift in fixation, head movement toward the target, or change in facial expression of the infant can indicate that the target has moved from an unsighted to a sighted field. The clinician should decide when imaging studies are indicated, independently or in consultation with a neurosurgeon or neurologist, on the basis of risk factors and the observation of ocular abnormalities, or signs such as nystagmus, developmental delay, poor growth, regression of skills, and seizures.
During the ocular health assessment and systemic health screening of infants and children of any age, it is important to remember that health care providers are responsible for recognizing and reporting signs of child abuse, a significant problem in the United States.
Optometrists have a uniquely important role in diagnosing child abuse including Shaken Baby Syndrome (SBS) because external eye trauma, and retinal trauma (hemorrhages, folds, tears, detachments, and schisis) are common ocular findings from child abuse.
In many states, optometrists must report suspected child abuse or neglect to the state child welfare service. Failure to report a suspected case of child abuse puts that child, his or her other siblings, and possibly a parent/caregiver in danger of continued abuse at home.
- Assessment and Diagnosis
Upon completion of the examination, the optometrist assesses and evaluates the data to arrive at one or more diagnoses and establishes a management plan. In some cases, referral for consultation with or treatment by another optometrist, the patient's pediatrician, primary care physician, or other health care provider may be indicated.
