Pediatric emergency medicine trisk 149

FIGURE 28.2 Patient’s head is being rotated passively to patient’s left as he looks straight
ahead. This causes displacement of eyes into right gaze. Left eye adducts fully, showing no
visible sclera medially. Subtle right sixth nerve palsy demonstrated by failure of right eye to
abduct fully: Sclera is still visible laterally on right eye.

EVALUATION AND DECISION


The history should include period of onset, progression, duration and severity,
family history of strabismus and amblyopia, history of trauma, as well as history
of any other medical problems. As referenced above, comparing old family
photos may be of utility.

FIGURE 28.3 Right third cranial nerve palsy. When looking straight ahead with left eye, right
eye rests in a hypotropic and exotropic position. Note right ptosis. Right pupil is involved
(mydriatic), but both pupils were dilated pharmacologically by examiner just before this
photograph was taken.


FIGURE 28.4 Patient is looking upward. Right inferior orbital wall blowout fracture causes
restriction of upward gaze in right eye. Note light reflexes (Hirschberg test). Left reflex (arrow
) is lower in reference to pupil than right reflex, indicating the presence of a right hypotropia.

The physical examination should be complete, with specific focus on the
neurologic and ophthalmologic evaluation. The ophthalmologic examination
should include visual function, pupillary activity, and extraocular movements.
The presence or absence of ptosis, lid retraction, proptosis, or enophthalmos
should be noted.
The Hirschberg light reflex is a helpful screening test in determining whether
strabismus is present. The physician should shine a penlight or direct
ophthalmoscope light at the patient’s eyes from 2 to 3 ft while the patient is told

to look at the other end of the room. In younger children, the patient may choose
to look at the light itself, but efforts should be made to distract the child with a
more distant target. The examiner should observe the white dot light reflex that
appears on the cornea, overlying the iris or pupil of each eye. In the normal state,
the light reflex should be located in a nearly symmetric position and falls slightly
off-center in the nasal direction in both eyes ( Fig. 28.5 ). If the eyes are
misaligned, symmetry of the Hirschberg light reflex would not be preserved (
Figs. 28.4 and 28.6 ).
The cover/uncover test further helps to tease out tropia (manifest strabismus)
from phoria (latent strabismus). For the cover test, with the patient fixating at a
distance, cover one eye and observe the other. If the uncovered eye moves or
shifts into alignment, an ipsilateral tropia is present. The uncover test will divulge


a phoria. Pathology is noted when a previously covered eye shifts back into the
orthotropic (straight-ahead) position.

FIGURE 28.5 Normal Hirschberg light reflex test. Light reflexes fall symmetrically in each
eye.

FIGURE 28.6 A: Left exotropia. Note medial displacement of Hirschberg light reflex in the
left eye. B: Left esotropia. Note lateral displacement of Hirschberg light reflex in the left eye.

Two findings are especially helpful in assessing whether strabismus is
emergent: (1) the presence or absence of double vision and (2) the status of the
eye movements. Although young children may not complain of diplopia, this
symptom often indicates an acute or subacute onset of ocular misalignment.
Nonemergent childhood strabismus is usually not associated with double vision
because the brain becomes adept at suppressing the misaligned, nonfixing eye. If
a child complains of diplopia, ophthalmology consultation is appropriate, even if

no obvious strabismus is apparent.
If the eye movements are completely full and symmetric, a neurogenic palsy or
restrictive phenomenon can be ruled out, and one can be virtually be certain that
the strabismus is not emergent. Problems that cause emergent strabismus do so by
impairing the action of one or more muscles. If there are any questions about