The health of your eye muscles finally regulate the health of your vision. The eyes may move up, down, right, left, inward and outward, constantly parallel to each other. Your capability to coordinate the movement of those muscles significantly determines your degree of vision fitness.
In order to retain the physical fitness of those muscles, you must work them out just as you would another muscle group, beginning with a warm-up. When you are prepared, extend your eyes as high as they could go without striving while you inhale.
Hold the breath, and once you are prepared to exhale, stretch the muscles in the extreme down position and breathe out. Then extend up to the right and down to the left, and lastly, up to the left and down to the right. If you sense any remaining tension in the muscles, stretch the breath somewhat and reduce the level of extending.
Remember, vision physical fitness develops during exercise in a relaxed way. Like any physical fitness procedure, do a cooling off work out. Rub your hands together till your palms are warm, then lightly cover your shut eyes with the palms of the hands.
Keep your eyes covered for a moment or two. Repeat it. Not only will you unwind your eyes, but you will likely experience quietness of the head as well.
Whenever you remove your palms, you will observe that colours are much brighter, you will see more contrast and you will enjoy a wonderful, relaxed feeling in the eyes and brow muscles.
Here is another useful exercise: Turn your eyes in, crossing them. Then gradually bring the thumb to the nose and sense the eye muscles pulling in.
These inner recti muscles are the turning-in muscles. In case the interior recti do not coordinate well, the eyes may depend on the ciliary muscles rather, that could cause a focusing muscle spasm and blurring. There is a link between the turning-in of the eyes and the capability to focus.