An ophthalmic assistant, technician, or technologist has a great responsibility when examining children. These early visits should be positive, to help form the child’s opinions and feelings toward eye care, and to identify vision issues early. For example, amblyopia, the most common cause of visual impairment among children, affects about three of every 100 children, according to the National Eye Institute. If identified and treated in young children, amblyopia’s effects on adult visual systems, such as monocular visual impairment, are reduced. To identify amblyopia and other conditions, here are the ophthalmic technician elements of a complete pediatric eye exam.
1. Obtain patient history.
The parents should provide answers to questions such as: Do they notice a problem? What do they see? Did the pediatrician send the child to you? Why?
2. Observe your patient.
Does the child have a head posture: face turn, head tilt, chin up or down? Is there an obvious strabismus or ptosis? Is there nystagmus? If your patient wears glasses, does she look through the glasses or look around them?
3. Assess distance vision.
The patient’s age and ability will affect this assessment. A child who knows her letters can read your vision chart. A child who isn’t able to read letters may be able to perform a matching test with you; LEA symbols and HOTV tests are excellent vision tests. Allen pictures, however, are not a good method for evaluating vision, as the optotypes are not uniform in size and shape.
You can use a single optotype starting at 20/100. Show one optotype per line, reducing the size one line at a time until the child misses one. Then, increase the optotype to one size larger than the child missed. The child needs to correctly identify three out of four optotypes in a line for you to determine the child accurately sees that size. If you are using LEA symbols or HOTV, present single optotypes only. Linear acuity is very difficult with these tests.
Proper occlusion is necessary for accurate vision assessment. If the child is older and cooperative, you can hold an occluder over the eye not being tested. Do not let the child hold the occluder. Watch the child carefully for peeking. A child with poor vision in one eye will do whatever he can to look around your occluder. Make note if the child uses a particular head posture for his best vision.
For young children, or for children who do not allow you to hold the occluder properly over their eyes, place an adhesive patch on the eye not being tested. The patch may upset the child momentarily. If the child is upset with only one eye occluded and not the other, this is a sign of a substantial difference in vision between the two eyes.
If the child is too young or unable to play a matching game with you, use a small toy or fixation target and observe the child’s fixation on the object. If the child can follow the target well with both eyes, you can then attempt to assess the child monocularly. It is not sufficient to use your hand, or for the parent to use her hand, when evaluating monocular fixation.
Children with nystagmus often use a head posture to obtain their best vision. You may need to put an occlusive patch on these patients, so they can use their best position. It is important to check children with nystagmus monocularly and binocularly. Patients with nystagmus may have better binocular vision. The near vision may be better than the distance vision too. Parents need to know the best acuity for school, which means testing these children monocularly and binocularly, with distance and near fixation. If you have a Spielmann, or frosted, occluder, use it for children with nystagmus.
Evaluating children with low vision requires patience and attention on your part. If a child cannot see the largest target on your vision chart, you have some options for checking vision. You can walk the child up to the chart until he can see the letter. Make note of how close the child is. This can be challenging and sometimes impossible in rooms with mirrored vision charts. It may be easier — and more accurate — to use individual letter cards. There are single optotype LEA symbol cards for low vision screening as well as HOTV letter books.
4. Assess near vision, when able.
Especially when a child has poor distance visual acuity, make an effort to obtain near vision. Use the proper technique for occluding each eye. This can be difficult with young children who do not know the alphabet; there are some good near-vision cards for preschoolers. You should also test near vision with children whose parents are concerned with their reading skills and if the child states he has trouble or is uncomfortable reading.
5. Screen for binocularity.
This step is a good addition to your evaluation for children 3 years and older. Use of the Randot Butterfly test is most helpful. A child who can see the Randot Butterfly has good binocular vision. This test is more sensitive than the Titmus Fly for evaluating binocularity. A child who does not see the butterfly needs a thorough assessment for strabismus.
6. Evaluate alignment.
Corneal light reflex tests can be performed on almost every child (unless the child won’t open his eyes!).
The Hirschberg test is the easiest test to perform, using the corneal light reflexes while the child fixates a light at 33 cm. If the light reflexes are symmetrical and centered in each pupil, or perhaps slightly nasal in each pupil, the eyes are straight. If the light reflex in one eye is more nasal than the other eye, there is an exotropia, or strabismus, in which the eye turns outward. If the light reflex is more temporal, there is an esotropia, in which the eye turns inward. If the light reflex is higher on one eye than the other, the eye with the higher light reflex has hypotropia, in which the eye turns downward, and there would be a hypertropia, in which the eye turns upward, if the light reflex is lower on the cornea of one eye.
For each millimeter of deviation, there is 7 degrees or 15 prism diopters deviation. An estimate of 30 prism diopters of deviation is considered when the decentered light reflex is found to be at the edge of the pupil; if the light reflex is halfway between the pupil and the limbus, the estimate is 60 prism diopters and 90 prism diopters if the light reflex is at the limbus.
You can perform a Krimsky test with a light source at 33 cm and hold a prism in front of the deviating eye. This test is more accurate than the Hirschberg test, but requires the child to allow you to hold a prism in front of one eye. You center the light reflex in one eye and place a prism in front of the deviating eye, adjusting the prism power until the light reflex in the deviating eye is aligned with the fixating “straight” eye. Use a base-out prism for esotropia and a base-in prism for exotropia.
7. Call in the doctor.
There are times the physician should see the patient before dilation:
- Children who have a pupil anomaly, specifically anisocoria, afferent pupil defects and nonreactive pupils
- Children who have ptosis
- Children who have strabismus, based on physician preference
- Children who have very poor vision, again depending on physician preference
- Children who are uncooperative
- Children who have conjunctivitis, a foreign body, or a corneal abrasion
Additional factors: If the child is uncomfortable or infectious and the presence of any iris anomalies.
8. Have fun with your patients!
Relax, smile, talk quietly, and be friendly with them. Try and “read” the kids who come to see you. Many need a little bit of time to get used to you. If the child is inconsolable, cut your losses and have the doctor come in. Don’t take it personally. The most important thing is that the child has the best exam possible. OP