The practice of Yoga in general can help you improve your eyesight. Poses like downward facing dog or any inversions that help circulate the blood to the head, face, neck and shoulders, energize and relax our vision. Deep breathing also helps immensely. However, there are specific Yogic exercises, that when followed regularly can not only help you relax your eyes but also improve your eyesight.
Sit comfortably and take a few deep breaths before starting the exercise. Rub your hands vigorously to warm them up then gently cup your eyes with both the hands. Repeat this a few times, until you see complete darkness. Then rub your hands and gently massage your eyebrows, bridge of the nose, cheekbones, ears and forehead to completely relax you facial muscles.
Sit straight and look to the most left side and hold your gaze to stretch the eye muscles. The return to look straight. Relax your eyes by cupping them again or blinking a few time. Repeat the same thing to your right. This exercise has to be repeated for other eye positions such as up, bottom, right top corner, right bottom corner, left bottom corner and left top corner, nose tip and a far away object. But remember to relax your eyes each time you return to look straight. You can then repeat the same movements in a dynamic form, by constantly shifting your gaze from extreme left to right, relax and then look up and down. Likewise you can follow trataka, a technique of staring at the candle without blinking or simply look at some point far and when your eyes give up, close them and recall the images.