Can intermittent strabismus present with a normal exam?

Can Intermittent Strabismus Present with a Normal Exam?

Yes, intermittent strabismus can absolutely present with a normal exam because fusional control can vary substantially from visit to visit or even within the same visit, meaning the eyes may be aligned at the time of examination despite having intermittent misalignment at other times. 1

Key Diagnostic Considerations

Variability of Presentation

• Fusional control in intermittent strabismus fluctuates significantly, and the deviation may not be manifest during clinical examination if the patient is maintaining good fusional control at that moment 1
• The deviation is specifically recorded as intermittent exotropia (X(T)) or intermittent esotropia when it is not constantly present, distinguishing it from constant deviations (XT or ET) 1
• In infants under 3 months, intermittent esotropia is considered normal visual development and does not necessarily predict constant strabismus 2

Factors That Unmask Intermittent Deviations

The medical history should specifically document when the deviation occurs, as intermittent strabismus typically manifests:

• When the patient is tired, ill, or daydreaming 1
• When viewing distant objects (particularly for intermittent exotropia) 1
• During periods of inattention or fatigue 1

Critical Examination Techniques to Detect Hidden Deviations

Sensory tests (stereopsis) must be performed BEFORE visual acuity and alignment measurements because monocular occlusion during standard testing can dissociate the eyes and either unmask a latent deviation or cause reduced stereoacuity measurement 1

To properly assess intermittent strabismus when initial examination appears normal:

• Use the prism and alternate cover test, which measures the total deviation (both manifest and latent components) and is more sensitive than simple observation 1
• Perform prolonged observation, as strabismus may emerge during the course of examination 1
• Assess distance stereoacuity in addition to near stereoacuity, which may detect reduced distance fusional control even when near alignment appears normal 1

Special Circumstances Requiring Heightened Suspicion

Variable Strabismus Patterns

In myasthenia gravis, strabismus can be completely variable and may temporarily disappear with rest or ice pack testing, making the examination appear entirely normal at certain times 1

• The ice test (2 minutes for ptosis, 5 minutes for strabismus) may demonstrate reduction of misalignment that was not initially apparent 1
• Strabismus and diplopia may take on entirely different patterns with fatigue or repetition of examination 1

Age-Specific Considerations

• In children under 3 months, intermittent esotropia is normal and most cases resolve spontaneously 2
• If esotropia persists beyond 3-4 months or becomes constant, ophthalmological evaluation is mandatory as binocular vision can degrade rapidly 2

Clinical Pitfalls to Avoid

The most common error is performing monocular occlusion tests (like visual acuity) before assessing binocular alignment, which can dissociate the eyes and interfere with accurate assessment of fusional control 1

Do not rely on a single examination to rule out intermittent strabismus, as alignment can vary substantially between visits 1

Indicators of progression that may be subtle on examination include:

• Worsening control of the deviation 1
• Reduction in stereoacuity 1
• Development of suppression 1