Yes, computers cause eyestrain, which ruins your vision. But if you go on vacation and get lots of rest with no reading or computer work, your eyes will improve again.
Practice 20/20, which means every twenty minutes, stare off into space or out a window for at least 20 seconds to give your eyes a rest. This will help somewhat.
Mostly though, your eyes are getting worse because they are changing shape as you get older. The visual image in your eyes is focused in front of your retina intead of on your retina. It's because your retina has moved back as your eye changed shape.
As you get older, your lens will get rigid, and it will be difficult to focus on close things by flexing that lens. Then you won't be able to see far away or close up.
