How does lazy eyes develop?

Lazy eye: Lazy eye is the lay term for amblyopia, a condition where the vision in one eye does not develop properly. It is treatable if diagnosed in childhood. Causes include strabismus, a high refractive error in one eye, childhood cataracts and ptosis to name a few. The term lazy eye is often misused to mean wandering eye (strabismus) or a droopy eyelid (ptosis) both of which are treatable in adults.