Believe me, that is the last thing you will have time for at OCS (especially the first 9 weeks). While you get some "free time" in the evenings, it is almost always occupied by: class drill practice, studying, polishing your boots, preparing for upcoming inspections, hygiening, etc. If you have a Big 4 billet (Pres, VP, Med Body, and Adj) you have even more stuff to do.
Pshh, I read the entirety of that history of the US Navy book they give you for that one "class" in the first 9 weeks and I was an honor graduate.
. (with lots of squinting and "uhhh.... sss--sleven?". Really though, have you discussed this with your OR? Told him or her your prescription? They'd know rather well whether or not your vision is going to make the MEPS cut enough for comfort. I've seen some comments on here that suggest if you can pass as your are, go for it and don't have surgery and the resulting obstacle of waiver, unnecessarily.