Out patient is seeing a therapist outside of the rehab place and Inpatient is staying in the rehab place and seeing a therapist
The lens helps the eye to focus on images.
"The Lens. The lens is composed of transparent, flexible tissue and is located directly behind the iris and the pupil. It is the second part of your eye, after the cornea, that helps to focus light and images on your retina."
I would say for because everything else is important <span />