Amblyopia or “lazy eye” is a condition of reduced or dim vision in an eye which appears to be “normal”. This is a serious eye defect, which often goes undetected in childhood until it is too late to have it corrected.
Amblyopia is estimated as affecting 2-4% of the population of Australia.
It is important for children to have their vision tested before they start school because a successful result depends on early treatment. Ideally, children should be examined at 3 years of age or earlier if an abnormality of the child’s eyes is apparent.
What are the causes of amblyopia?
In amblyopia, the eye can become “lazy” due to a variety of different reasons. However the two main causes are:
- Squint (Strabismus, aka eye turn): This is the most frequent cause and occurs when the eyes are not parallel/aligned correctly when focusing on an object. The eyes look in a different direction and the child either sees two objects or a blurry image. To avoid confusion, the brain will suppress (ignore) the image from the affected eye causing it become lazy (amblyopic). Sometimes the eye turn is not obvious and can only be diagnosed by special tests with an ophthalmologist.
- Refractive error in one eye (causing poor vision in one eye): The eyes may look aligned (straight) but if the vision in one eye is much stronger than the other, the child will use the good eye and suppress (ignore) the image from the weaker eye. A refractive error such as long or shortsightedness is present in the weaker eye, causing the blurry image.
What are the symptoms/signs of amblyopia?
Often there are no symptoms as amblyopia often only affects one eye so with both eyes open the child is unaware of any problems. However, there are some characteristic actions that may indicate that a child has a vision problem. These include:
- An eye turn (may be present constantly or just sometimes-e.g. when child is tired). This needs immediate attention- a child will not outgrow an eye turn.
- Excessive rubbing of eyes
- Closes or covers one eye when looking at an object
- Excessive blinking and/or squinting of eyes
- Irritability when doing close work
- Brings objects close to eyes
- Poor coordination: e.g. trips over small objects
What is the treatment for amblyopia?
There are 3 main methods of treating amblyopia. The most widely used is “patching”, or covering the good eye to force the child to use the amblyopic “lazy” eye. Patching alone is often successful with children. In some instances, glasses are prescribed to correct refractive errors. In others, muscle surgery may be necessary to correct the misaligned eyes.
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