Amblyopia is caused by an abnormality that interferes with the normal process of seeing.
This interference can occur at the level of the eye, at the connections between the eye and the brain, or in the brain itself.
The stronger eye becomes dominant and retains good vision, but in the affected eye, the nerve connections between the brain and that eye fail to develop normally, and the brain learns to ignore visual information from that eye.
The most common causes of amblyopia are -
Misalignment of the eye or strabismus
Cloudiness of the normally clear visual pathway, due to abnormalities
Blockage of an eye due to trauma, drooping eyelid, etc.
Vision problems such as nearsightedness, farsightedness, or astigmatism, if uncorrected, can cause amblyopia
Trauma to the eye or head
Diseases that affect the eye, such as cataracts
Some psychiatric conditions
Excessive use of tobacco, alcohol or other drugs