What about "magic eye" hidden images stereograms – Do they improve your vision?

http://www.vision3d.com/sghidden.html

http://www.visionworksusa.com/magic_eye_exercise.php

I just tried to focus on some of theses images.

I still don’t see the 3D images after a few tries

After a few minutes of focus, it seems to put strain and stress on the eyes.

Does not seem to work for me so far…