I had a buddy in grade school who had poor eyesight. He was having problems reading the chalkboard. The optometrist said that he didn't need glasses, and just had to strengthen his eyesight. He was given "exercises" to do. - Look out of a window and focus on something far away. Then focus on the glass (the watermarks or dust on the glass). Then focus again on the thing in the distance. - Hold a pencil 6 or 8 inches directly in front of your face, focus on it for a few seconds. Then focus on the wall behind it. Repeat for a while. Then hold the pencil to the side, and do the same. - Read a page of a book with it held out at arm's length. Then read the next page with it close to your face. Exercises like that. The guy never did get glasses. And it makes even more sense nowadays, because we spend so much time with our eyes focused at one distance. But as a side note - If you find that you can focus perfectly fine during the day, but can't focus properly or as easily at night, that can be caused by cheap LED lightbulbs. I don't know the science behind it, but it's caused by cheap LED bulbs. Supposedly it's not the color of the bulbs, instead it's the flicker or something.