Eye yoga can't decrease your eye power, but it does have many benefits for your eyes. It can relax your eye muscles. There are two types of muscles around human eyes. One is the extra ocular muscles, which help the eyes move around. When being used excessively, the muscles get tight and stiff easily. So massage is recommended to loose the stress of the extra ocular muscles. You can also train this kind of muscles by moving your eyes up and down, right and left repeatedly without moving the head. The other type is the internal eye muscles, which help the eyes focus objects according to different distances by altering the eye shape. When looking at the close focus for a period of time, your internal muscles also get tight like the extra ocular ones.
