Hello,

I was wondering if frequent straining (from constipation, working out, lifting weights, lifting heavy objects, etc) could cause vision to get worse? Could frequent straining of the eyes cause it too; that is, often struggling to see things far away?

Those are 2 very separate questions. I'm sure in most languages that the same word isn't even used to describe them.
Physical straining can break blood vessels in the white of you eye. I know women who have experienced this from giving birth. But it didn't effect their vision.

Straining to see without glasses or other corrective lenses is a different issue.
One optometrist explained it this way when my very nearsighted daughter was very young. If you never see clearly, you can't learn to focus.