Explaining lazy eye or amblyopia

What is amblyopia?
When an eye has not received adequate use during early childhood the reduced vision known as amblyopia or "lazy eye" can be the result. This condition is not an eye disease, and cannot be corrected directly by glasses or contact lenses. This is because amblyopia is related to the way that the brain is developed and receives images. It is estimated that 3% of children under 6 years have some form of amblyopia.

How does amblyopia develop?
During the critical period of early childhood from birth to 6 years of age, anything that interferes with clear vision in either eye can result in amblyopia. Both eyes must receive clear images during this period to stimulate the brain, prompting it to develop fully.
For example, if a young child has severe astigmatism, the images the eyes see are blurred. When these images are sent to the brain the brain receives them as blurred too. Without the stimulation of sharp images, the brain fails to develop the adequate apparatus to correctly interpret and process the images that are received from the eyes. It is almost as though the brain doesn't learn how to "see" clearly, and even if the visual problem of the eye is corrected later in life the image interpreted at a neural level may still be unclear.

What symptoms I should be looking for in my child?
The only way to detect lazy eye early is to have sight tests regularly throughout childhood. Children should be checked at birth, at 6 months, and then annually until 7 or 8 years of age whether they seem to have a problem with vision or not. However if there is any suspicion of poor vision or crossed eyes it is advisable to bring your child to an optician, GP or eye surgeon earlier. The earlier the treatment, the better the opportunity to correct the vision loss.

What treatments are available?
Before treating amblyopia, it is necessary to first treat the eye for the underlying cause:
• Glasses are commonly prescribed to improve focus or misalignment of the eyes.
• Surgery may be performed on the eye muscles to straighten the eyes. This works by allowing the eyes to work together better.

Once the underlying condition of the eye has been corrected, amblyopia can be treated by:
• Occlusion therapy: Patching/covering one eye is the most common treatment. The better-seeing eye is patched, forcing the "lazy" one to work thus strengthening its vision. Your child will be given the patch that suits them best - this could be a disposable adhesive patch or a patch held in place with elastic. The more complete the blockage of light from the eye, the more effective the treatment.
• Medication, in the form of eyedrops or ointment, may be used to blur the vision of the good eye in order to force the weaker one to work.