Eye dysfunction can definitely cause headaches.

Twice a month, when I have to sit down and pay bills, on computer and some by paper, I end up with a whopping migraine by the end of the session. And I know all the tricks to counteract the "wonky eyes" and all that is going on.

Normally, I don't really read, I just sort of skim over things. I keep my computer screen blown up to about 150%, if the websites still work that big.
(Use Ctrl + to make it bigger, Ctrl- to make it smaller, Ctrl 0 to get it back to normal. Or, hold Ctrl and scroll-wheel up for bigger, down for smaller, and if you get too mixed up, Ctrl 0 (zero) to get back to normal size.)

But when paying bills, I have to make sure I get all the numbers and passwords right, so it's concentrated, real, eye-work, and I pay the price with the resulting headache.

Is also why I can't do much reading up on things, or searching them out, myself. Wonky eyes don't allow it.