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Binocular vision assessment
Strabismus
Key Points
- •Worth's 3 grades of binocular vision: Grade 1 - simultaneous macular perception; Grade 2 - fusion (sensory + motor); Grade 3 - stereopsis (the highest level).
- •The critical period for binocular vision development is birth to ~2 years; disruption during this period (by strabismus, amblyopia, or deprivation) may permanently prevent binocularity.
- •Worth 4-dot test: 4 dots = fusion; 5 dots = diplopia; 2 dots = left eye suppression; 3 dots = right eye suppression - the most commonly tested binocular assessment in exams.
- •Stereoacuity of ≤60 arc seconds indicates fine stereopsis (foveal-grade); random-dot tests (TNO, Randot) are more reliable than contour-based tests (Titmus) as they eliminate monocular cues.
- •Monofixation syndrome is the most common and best functional outcome after infantile esotropia surgery - a small residual deviation (≤8 PD) with peripheral fusion and subnormal stereopsis.
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- Definition
- Epidemiology
- Aetiology and causes
- Pathogenesis
- Classification
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