Non-working = lazy
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 or one from a different direction. The brain chooses to keep the best image & quit "looking" at the other image. If the brain has turned off the lazy input for too long, it may be lost forever.