What is amblyopia (lazy eye)?
Amblyopia is also known as lazy eye. It is an early childhood condition where a child’s eyesight in one eye does not develop as it should. This poor vision is not correctable by glasses or contact lenses. The brain, for some reason, does not fully acknowledge the images seen by the amblyopic (lazy) eye.
This almost always affects only one eye but it may also happen in both eyes.
Amblyopia is common, affecting approximately 2 to 3 out of every 100 people. The best time to correct a lazy eye is during infancy or early childhood.
What causes amblyopia?
Any condition that affects the normal use of the eyes and visual development can result in amblyopia. During early childhood years, the visual system changes rapidly and eyesight continues to develop. If a child cannot use his or her eyes normally, the vision will not develop properly and may even decrease.
In many cases, the conditions associated with amblyopia may be inherited.
There are 3 major causes of amblyopia:
- Strabismus (squint or misaligned eyes) This is a common cause of amblyopia. When a child has a squint, the misaligned eye is ‘turned off’ to avoid double vision, and the child uses only the better eye. This misaligned eye then fails to develop its vision normally.
- Anisometropia (unequal focus and Refractive errors) Amblyopia can occur in one eye when the eye is more short-sighted, far-sighted or astigmatic than the other eye. This is probably the most difficult type of amblyopia to detect since the child may appear to have normal vision when both eyes are open. When there is an unequal focus or degree, the unfocused (blurred) eye is ‘turned off’ and eventually becomes ‘lazy’.However, if there is a high amount of short-sightedness, far-sightedness or astigmatism in both eyes, both eyes can be amblyopic.
- Cloudiness in the normally clear eye tissues Eye disease such as a cataract in early childhood may also lead to amblyopia. Any factor that prevents a clear image from being focused inside the eye can lead to the development of amblyopia in a child. This often results in severe amblyopia.
How is amblyopia treated?
Amblyopia is treatable if it is detected early. The best time to correct amblyopia is during infancy or early childhood while the visual system is still developing. After 9 or 10 years old life, the visual system is fully developed and usually cannot be changed anymore and the vision will not improve. Early detection offers the best outcome of amblyopia treatment.
To correct an amblyopia, a child must be made to use his/ her weaker eye. Treatment of amblyopia includes eyeglasses, patching or eyedrops.