Amblyopia (lazy eye)
Amblyopia is an important condition that affects young children. If detected early enough, which usually means before the age of 5, it can be treated successfully. If not detected in time it can result in permanent loss of vision from one eye.
Amblyopia happens when a baby's eyes do not produce a single message to the brain. Normally both eyes focus whatever the baby is looking at on to the same part of the retina at the back of the eye. The brain then ‘sees’ a single picture. But if the eyes are not perfectly aligned, as in strabismus (squint), or if one eye is longer (or shorter) sighted than the other, the brain receives 2 messages. In an adult this would result in double vision or blurred vision.
But young children's brains are different from adult brains. Until the age of about 5, a child's brain can suppress (‘switch off’) the unwanted picture and only receive the message from one eye, allowing the child to see clearly. This ability of the brain to suppress one of the images it is receiving is initially reversible, but eventually becomes permanent. When this happens, the brain will never register the pictures coming from that eye.
For this reason it is vitally important to make sure that a child is seeing with both eyes. Some simple tests at home will usually uncover this problem. When amblyopia is found, treatment usually involves treating the underlying cause. This might mean surgery for a squint or a prescription for glasses if there is a refractive error (long sighted or short sighted).
Often the ‘good eye’ will need to be covered for a while to stimulate the brain to receive the picture from the ‘lazy’ eye.
There are many ways to check that your child is seeing normally. If you have any doubts, seek advice as soon as possible.
Last Reviewed: 05 September 2005
