diagnosis
Last reviewed 01/2018
This may be difficult in infants and young children. Diagnosis requires an expert clinical examination to rule out other causes of reduced vision and to identify the underlying associated amblyogenic factors (1).
- inquire about torticollis (abnormal head posture), nystagmus, squinting of one eye (all of which indicate strabismus) or strabismus from parents
The diagnosis of amblyopia is based in the presence of a redued visual acuity (generally 2 lines of an acuity letter chart) associated with an amblyogenic risk factor and without ocular structural abnormalities
- finding of reduced visual acuity in a child is not a diagnosis of amblyopia
- in the absence of an obvious amblyogenic factor and failure to restore normal vision by an accurate spectacle prescription should warrant further investigation to rule out other possible ocular or neurological pathology (such as optic nerve hypoplasia).
Visual acuity assessment in children
- in infants - behavioural techniques such as preferential looking can be used to measure acuity
- in older children (preliterate children) - booklets with letters or pictures (optotypes) can be used (2)
- it is important to use age related norms of the vision test when assessing since adult levels (6/6 as measured by Snellen chart or 0.0 LogMAR equivalent) are not attained till around 4-5 years.
- unilateral vision loss should be considered when the child displays more distress on closing one eye rather than the other (1,2,3)
Siblings of a child with amblyopia should be observed for risk factors and undergo vision screening.
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