Refractive error >>> post-study headache?

So yesterday, I went to library to push myself to study the whole day. I only brought my OB book (cuz Gynaec is the last thing to worry right now) . I managed to finish 8 hours study but guess what. After that I developed severe headache. That night I can't do anything. I just lie on my bed, hoping someone would come and feed me analgesic. Thank God, somebody did come and give me Etodolac :')

As usual I will try to find the cause for everything. So after some calculation, I think the most probable cause for my headache is my uncorrected refractive error. (Yes, I'm short sighted with -1.5 both eyes) Even though I have no problem with seeing things close to me, I know i was straining my eyes too much with reading for long hours. Andddd I'm not used to it *laughs*

I was pretty lazy to study before.

So nowwww. I need to correct my vision in order to prevent this in the future (<--- this is just me giving a reason to buy something). I made the first step to buy a pair of contact lenses. Colored ones. So, guess which color I picked. That, I'll tell later. Something is meant to be kept for a surprise, aye? Haha.

P/s: I don't know what's the relationship between buying a corrective lenses and preventing headache. But anyway, can't wait for my contact lenses! I'll get it tomorrow!