Amblyopia is caused by any condition that affects normal use of the eyes and visual development. In many cases, amblyopia may be hereditary, or passed down through the family. Amblyopia has three major causes.
Strabismus (misaligned eyes)
Amblyopia occurs most commonly with strabismus, which is misaligned or crossed eyes. The crossed eye "turns off" to avoid double vision, and the child uses only the better eye. The misaligned eye then fails to develop good vision.
Unequal focus and refractive errors
Refractive errors are eye conditions that are corrected by wearing eyeglasses or contact lenses. Amblyopia occurs when one eye is out of focus because it is more nearsighted, farsighted, or astigmatic than the other.
If one eye is out of focus, this unfocused (blurred) eye "turns off" and becomes amblyopic. The eyes can look normal, but one eye has poor vision. This is the most difficult type of amblyopia to detect since the child appears to have normal vision when both eyes are open. Amblyopia can also occur in both eyes if both eyes have very blurred vision. This can happen when there is a high degree of nearsightedness, farsightedness, or astigmatism.
Cloudiness in the normally clear eye tissues
An eye disease such as a cataract (a clouding of the eye's naturally clear lens) may lead to amblyopia. Any factor that prevents a clear image from being focused on the retina at the back of the eye can lead to the development of amblyopia in a child. This is often the most severe form of amblyopia.
If your ophthalmologist finds a cataract in the eye, surgery may be required before amblyopia (lazy eye) treatment can begin.
Next Page: Amblyopia: Lazy Eye Diagnosis