What is/are the cause(s) for the lazy and what is/are the treatment(s) for the lazy eye?

Cause varies: Could be poor vision on one side, obstruction by a droopy eyelid, a problem with the muscles or no reason at all. The treatment varies from covering the good eye to force the brain to see through the lazy one, to surgery if the eyes are focused so far apart that they can't be brought together.

Non-working = lazy: Lazy eye refers to several issues that can cause the brain to quit accepting input from an affected eye, so it is not working =lazy. Example: 1 eye presents a sharp image to the brain, 1 a fuzzy image. The brain chooses to keep the sharp image & quit "looking" at the other image. Timed patching of the good eye makes the brain keep using the weak eye. The eye dr works to improve the weak eye.