• “Crossed eyes” is often a chief complaint indicating inward deviation of the eyes, or esotropia. Because abnormal eye movements of any type may be interpreted as “crossed eyes,” this chapter will cover any misalignment of the visual axes, or strabismus (see table Common Presentations of Strabismus).
  
  
  

  Common Presentations of Strabismus

  
  
  
• Strabismus is reported to occur in approximately 4% of children less than 6 years of age. It may be constant or intermittent; present in all fields of gaze or restricted to only a few; and present with near fixation, far fixation, or both.

• Transient sixth nerve palsy: may be seen in neonates, manifesting clinically as a lack of lateral gaze; it typically resolves within the first 6 weeks of life. Many believe this to be secondary to increased intracranial pressure during delivery.
• Pseudoesotropia: not a true strabismus; an optical illusion of asymmetric nasal sclera created by prominent inner eyelid skinfolds and a wide, flat nasal bridge.
• Möbius syndrome: a congenital condition presenting as an esotropia and an expressionless face, caused by unilateral or bilateral sixth and seventh nerve palsies. Associated chest and limb abnormalities may be seen.
• Duane retraction syndrome: congenital esotropia, presents with restriction of lateral gaze.
• Fourth nerve palsy: more commonly congenital than acquired. The affected eye is in upward deviation, secondary to a weakness in the superior oblique muscle. Amblyopia is uncommon because the child usually develops a head tilt in order to maintain ocular alignment.

• Determine if the patient has a history of abnormal eye movements consistent with strabismus or if the patient currently has an abnormal examination.
• Strabismus must be addressed in a timely manner because if left uncorrected, amblyopia (a reduction in visual acuity) may result.

• Abnormal eye movements may be intermittent and difficult to elicit in the office setting. A complete examination must be performed, with special attention to the ophthalmologic and neurologic exams, in order not to miss strabismus.

• Provide the appropriate referral to a pediatric and/or neuro-ophthalmologist.

Question: When was the onset of symptoms?
Significance: A large percentage of newborns will manifest a transient esotropia or exotropia. Esodeviations or exodeviations persisting after the age of 6 months, or constant deviations, are considered abnormal and warrant additional evaluation.

Question: Is there a history of head tilting?
Significance: Head tilting may represent a vertical eye muscle problem. A full ophthalmologic examination is needed.

Question: Does the deviation occur at a particular time of day?
Significance: Eye fatigue or sleepiness may bring out symptoms of eye crossing.

Question: Does the patient have any other symptoms or change in mental status?
Significance: Vomiting, specifically early morning vomiting, may be a sign of increased intracranial pressure, and warrants immediate evaluation.

Question: Does the child seem to keep their head turned to one side?
Significance: Children with Duane syndrome will frequently keep their head turned to one side in order to keep their eyes aligned and to avoid the side of the eye with limited abduction.

Question: Has the child been noted to close or cover one eye?
Significance: This may be a clue to the presence of diplopia, and may be seen in some types of strabismus.

Finding: Transient esodeviation
Significance: May be observed in a normal infant less than 2 months of age; not indicative of pathology.

Finding: Esodeviation persisting after 2 months, or constant esodeviation
Significance: Should be evaluated by an ophthalmologist.

Finding: Any suspected defect in ocular motility noted after the age of 3 months
Significance: Warrants additional evaluation.

Finding: The finding of leukokoria (a white pupillary reflex)
Significance: Leukokoria is the most common initial sign of retinoblastoma. Immediate referral is warranted.

Finding: Opacity of the usually clear crystalline lens
Significance: This physical finding suggests the presence of a cataract.

Finding: The presence of a broad epicanthal fold, which may obscure the medial aspect of the sclera. A flat nasal bridge might be noted.
Significance: This finding may create the impression of strabismus. This condition, called pseudostrabismus, does not require referral.

Test: Corneal (Hirschberg method) light reflex is performed by holding a light source 33 cm in front of the patient and noting where the light reflex is on the cornea. The light reflex should be in the same spot in both eyes.
Significance: An esotropic eye will have a temporally displaced light reflex, whereas an exotropic eye will have a nasally displaced reflex. In the case of pseudoesotropia, the light reflection will be symmetrically placed.

Test: Cover-uncover test. Each eye must be tested individually. One eye is covered, and fixation movements are observed in the other eye. The cover is then removed and after a few seconds placed over the other eye. The uncovered eye is observed for movement.
Significance: Accurate to assess the presence of tropia. If movement is not noted, then no tropia exists; if movement is noted, then the diagnosis of heterotropia is made. Outward movement indicates esotropia, inward movement indicates exotropia, upward movement indicates hypotropia, and downward movement indicates hypertropia.

Test: The alternate cover test. Each eye is tested individually. The cover is placed over one eye and is then quickly moved to occlude the other eye, to disrupt coordinated binocular function.
Significance: Similar to cover-uncover test, this test is used to detect phorias and tropias. If movement is noted in the uncovered eye, a phoria or tropia has been elicited. The results of this test and the cover-uncover test will allow the interpretation of the presence of a tropia, phoria, or both.

Test: A complete fundoscopic evaluation
Significance: Detects presence of cataracts or evidence of infections.

Test: Assessment of visual acuity
Significance: Amblyopia occurs even in cases of small-angle strabismus.

Acute changes in the neurologic status of a patient presenting with a nerve palsy, manifesting clinically as strabismus, may indicate the presence of increased intracranial pressure and warrants emergency neurologic evaluation.

Q: Up to what age is transient esodeviation considered to be within normal limits?
A: Transient esodeviation may be observed in normal infants up to 2 months of age. Transient esodeviation persisting after the age of 2 months or constant esodeviation should be evaluated by an ophthalmologist.

Q: Could the physical finding of head tilting represent a problem with the visual axis?
A: Head tilting may represent a vertical eye muscle problem and should be referred for evaluation.

Q: Does pseudoesotropia resolve?
A: Frequently, pseudoesotropia will resolve as the child grows and the nasal bridge becomes more prominent.

• Strabismus detected by the primary care physician warrants referral to an ophthalmologist for a complete evaluation and properly paced therapeutic intervention.
• If underlying conditions associated with strabismus are suspected, evaluation by other specialists (e.g., neurologist, geneticist) may be indicated.

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