Presbyopia is a condition associated with progressively worsening ability to focus clearly on close objects, and eyesight recovery treatment for it is rather easy, for it only requires the improvement of ability to see objects within a fixed near distance. It is easier than to recover eyesight to a normal state as in myopia, and it is far easier to thicken the crystalline lens than to thin it. For example, the visual range of 40 cm is equivalent to a distance of using the thick eye lens of 1.5D, and it has only to recover by 1.5D. Eye dry syndrome is apt to be accompanied by decreased vision, and the eyesight training relieves the dry eye syndrome, a very light symptom, by causing the user to have watery eyes.