eye exercise have you done this so far?

We often take for granted the little things that really matter such as taking good care of our eyes by doing eye exercise. I know some exercises that my optometrist recommended to me one of this is to every 20 minutes you have to look farther than your pc like staring at a tree and just try to relax your eyes to its greenery or you could blink your eyes 20 times every 20 minutes I guess she says every 20 minutes because it has something to do with 20 -20 vision which is a perfect vision for a human eyes and by doing this one could actually have a good eyesight even how long you stay online on your PC. actually there are lots of ways and exercises for the eyes do you know of this care to share?