What is amblyopia?
Lazy eye, or amblyopia, is reduced vision in an eye that has not received adequate use during early childhood. This reduced vision is not correctable by glasses or contact lenses and is not due to any eye disease The brain, for some reason, does not fully acknowledge the images seen by the amblyopic eye. This almost always affects only one eye but may also affect both eyes. It is estimated that three percent of children under six have some form of amblyopia.
What causes amblyopia?
Both eyes must receive clear images during the critical period in childhood. Anything that interferes with clear vision in either eye during the critical period (birth to 6 years of age) can result in amblyopia. The most common causes are strabismus (crossed eyes), or a difference in image quality between the two eyes (one eye focusing better than the other.) If one eye sees clearly and the other sees a blur, the good eye and brain will suppress the eye with the blur. This can result in a permanent decrease in the vision in that eye.
Can anything be done to treat amblyopia?
With early diagnosis and treatment, the sight in the "lazy eye" can be restored. The earlier the treatment, the better the opportunity to reverse the vision loss. Amblyopia can usually be successfully treated up to the age of 7, but treatment for older children may sometimes be successful in improving vision and can be attempted
What treatments are available?
Before treating amblyopia, it may be necessary to first treat the underlying cause.
- Glasses are commonly prescribed to improve focusing or misalignment of the eyes.
- Surgery may be performed on the eye muscles to straighten the eyes. Surgery can help in the treatment of amblyopia by allowing the eyes to work together better.
The correction may be followed by:
- Patching or covering one eye may be required. The better-seeing eye is patched, forcing the "lazy" one to work, thereby strengthening its vision.
- 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.
What if amblyopia is not treated?
If not detected and treated early enough, amblyopia can lead to a permanent loss of vision with associated loss of stereopsis (three-dimensional perception).
Since amblyopia usually occurs in one eye only, many parents and children may be unaware of the condition. In Singapore, there is an eye screening programme where all children are screened at the age of 4. 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.