Amblyopia, otherwise known as lazy eye, affects ~ 3% of the population and negatively impacts on a person's sporting and academic abilities.

Amblyopia is a loss of clarity of vision in the affected eye in early childhood, arising from various causes. It can lead to a lifetime of poor vision in the affected eye.

In many cases this loss of vision in one eye is preventable if detected and treated in early childhood.

What causes Amblyopia?

Amblyopia develops when the visual cortex area of the brain is unable to develop properly in childhood. It is widely accepted that the visual cortex matures from birth to 8 years. There is evidence to suggest that the visual cortex can be improved in adulthood, but these improvements are incremental.

Normally both eyes coordinate together and the visual cortex combines the two images into a single image, providing binocular vision and depth perception. If the eyes are unable to work together effectively, the brain develops to favour one of the eyes to the detriment of the other. Once the brain is fully developed in adulthood, even if the weaker eye is corrected with spectacles or contact lenses the vision still remains impaired because the visual cortex has not developed properly.

There are two main causes of amblyopia:
baby squint smaller
1.  Strabismus or ‘squint’ - the eyes are not coordinated due to an error in the eye muscles alignment. This is the most likely cause to be treated in infancy because there is a visible sign and so parents are concerned, and the child is seen by an eye specialist and has surgery to align the eyes. Some eye diseases such as congenital cataract can cause amblyopia, because the cataract prevents the brain from receiving a good image, and again this is often treated in infancy.
2.  Anisometropic amblyopia - occurs when there is a big difference in the spectacle prescriptions between the eyes. Both eyes appear normal, the child seemingly has no problems seeing because he/she has one good eye. The lazy eye in this case often has a moderate/high amount of long-sightedness and/or astigmatism. This type responds really well with spectacles. This is relatively common, but is a more insidious cause of amblyopia. For this reason it is important for all children to have an eye examination to ensure their eyes are developing properly. 


How is Amblyopia treated?

Early treatment results in better outcomes in all types of amblyopia. If lazy eye is identified after the age of 8 years, there is often very little which can be done to recover the sight.  

The main treatment options include: 
  • surgery
patch smaller
  • spectacles
  • occlusion therapy (blocking the use of the good eye). Occasionally the good eye is ‘penalised’ using eye drops which make the good eye blurry so the lazy eye has to work.

We recommend that although there is a children’s vision screening programme, it is still advisable for children to have a comprehensive eye examination with an optometrist. We recommend a routine eye examination at the age of 3 years and 5 years, especially if there is a family history of lazy eye, as visual outcomes are best when treatment is started early. The Enable subsidy exists to provide free eye examinations and spectacles for children under 16 years old whose family have a community services card.


Buchanan Optometrists Ltd optometry practice in Christchurch is located at Church Corner within the Riccarton Clinic. As an independent optical practice we have the freedom to use suppliers that provide the best service and products to you.

btn readmore


Monday, Wendsday & Thursday
8:30am -5:30pm
8.30am - 7:00pm
8:30am -4:30pm

First Floor
Riccarton Clinic 
6 Yaldhurst Road
Upper Riccarton 
New Zealand
03 341 4850