Unfortunately no. You can't improve your vision by just looking at an eye chart. It is useless. Additionally there is no scientific proof that you can improve your vision to any noticeable level by eating carrots, or other supplements or any form of eye exercises.
No. Looking at an eye chart won't improve your vision. You should wear corrected lenses to help you see better. Or you can get lasik surgery when your vision has stabilized. To maintain your eyesight, you should not overuse your eyes and make them tired.