How does a child develop amblyopia?

Amblyopia. Amblyopia means loss of vision when the eye is not used. This is caused by a condition called "lazy eye"l. Because of a weak eye muscle (s), the affected eye does not move synchronously with the normal eye. Consequently, the normal eye dominates the function of "seeing" and leaving the affected eye to lose its visual function leading to blindness. If caught early, blindness can be prevented.
Poor image in 1 eye. Amblyopia occurs when the child's brain has a choice to pay attention to one eye or the other. If the image from one eye is less clear, points the wrong way, or has some defect making the image less sharp like a unilateral cataract, the brain will learn to ignore this and the vision centrally drops. This is termed amblyopia and is the reason some kids get a patch to force vision in the "bad" eye.