Why is it when i have a headache can't see very well?

Yes I have them about once a month. My Doctor diagnosed me with migrains(sp). Migrains can interfere with your sight. They can also cause a sick stomach,sensitivity to light,dizziness and body aches. You can also have what's called a silent migraine. Meaning you have the sight interference but no headache. If it keeps happening it would be a good idea to talk to your doctor. Hope this helps. Taylor