My nephew has a lazy eye, and has undergone vision therapy and also used eye drops at times. He is also nearsighted, so he uses prescription eyewear (eyeglasses) to correct it.
Vision therapy (patching one eye) is used to restore the vision by helping both eyes to work as a team. This is done by forcing the brain to use the amblyopic eye. A patch is placed over the stronger eye to force the weaker eye to be used more.
In using eye drops, one drop is placed in the good condition eye to blur its vision, so my nephew will be forced to use his other eye with amblyopia to strengthen it.