Amblopia, or poorly developed vision occurs in one eye of 3 to 4% of the population and is by far the commonest cause of loss of vision in the under 40s in the UK and the USA.The main causes of amblyopia are strabismus (squint) and/or uncorrected anisometropia (difference in prescription between the two eyes) especially when associated with hypermetropia (longsight).
Because vision develops very rapidly in the first two years of life, if a squint or anisometropic hypermetropia is undetected until later in a child's life it becomes increasingly more difficult to treat as time goes by. Needless to say, the earlier a problem is diagnosed the earlier treatment can be commenced an the more likely a favourable result. Babies should receive their first eye examination at six months. Waiting for a school vision check at the age of 4 or 5 years is often too late and the child may be left with a "lazy eye".
Treatment of amblyopia depends to some extent on the cause,. In the case of anisometropic amblyopia, the first step is constant wear of spectacles. For strabismic amblyopia, occlusion (patching) therapy is commenced immediately the anblyopia is diagnosed. Whilst there are other methods used to try and improve vision the current evidence is that occlusion is the most efficaceous.