As far as i know, poor eyesight won't cause headaches unless you got migraine. Usually, people who have poor eyesight may often suffered from blurry vision and eye strain that make me not see things clearly. But it does not cause headaches. But if you insist to do something with tired and strain eyes, it my further cause headaches for lacking of rest. And headaches are usually caused by stress and muscle tension. Also, caffeine, cheeses, and chocolate can also be the factor of headaches for some people.
Hmm, I don' t think so. As a nearsighted guy for years, I only get a headache when I am ill. But my poor eyesight never causes me to have a headache. Poor vision can only cause your eye strain and blurry vision sometimes, but definitely not headaches. If you get a headache usually, I don' t think it is caused by your poor eyesight. You may have something wrong with your body and you had better have an overall exam.