Intermittent Strabismus Diagnosis and Management
Key Diagnostic Considerations
- 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, 2
- 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, 3
- Intermittent strabismus typically manifests when the patient is tired, ill, or daydreaming 1, 2, 3
- Intermittent strabismus may also manifest when viewing distant objects, particularly for intermittent exotropia 1, 3
Critical Examination Techniques
- 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, 2, 3
- The prism and alternate cover test is recommended to measure the total deviation (both manifest and latent components) and is more sensitive than simple observation 1, 3
- Assess distance stereoacuity in addition to near stereoacuity, which may detect reduced distance fusional control even when near alignment appears normal 1, 3
Special Circumstances Requiring Heightened Suspicion
- 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 5, 6, 7
- The ice test (2 minutes for ptosis, 5 minutes for strabismus) may demonstrate reduction of misalignment that was not initially apparent 5, 6, 7
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, 2, 3
- 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, reduction in stereoacuity, and development of suppression 1, 3