Eyesight gets worse with age however sensibly and carefully we live. If we are not sensible, go without exercise, eat highly processed foods and too much carbohydrates, too little vegetable, we run the risk of getting diabetes which seriously affects the eyes. Too many hours with eyes on the screen is harmful.
However, the main deterioration is common in old age and this is macular degeneration. Basically, the muscles in the eye weaken with age, just as they do in other parts of the body. You can do eye exercises which will help a little. We use our eyes for everything, every day. It is natural that there is wear and tear.