In my experience is no longer able to exercise the full range of motion of the eyes, I think the muscles that controls focus tends to shorten due to lack of use

In my experience is no longer able to exercise the full range of motion of the eyes, I think the muscles that controls focus tends to shorten due to lack of use. Looking only at very short distance or objects will lessen the range of motion of the eye muscles. I am using a prescription eyeglasses before but it is not helping what helped is looking at distant objects while relaxing my eyes. Eventually the doctor said my eyes returned to 20/20 vision.