There's no optometry-specific stuff on the OAT, just general questions from biology, gen chem, org chem, and physics (plus quant and reading comp). I can't recommend enough getting the TopScore Pro CD to use for practicing sample tests, really helpful.
The math is all do-it-in-your-head or on scratch paper, which is a good skill to start brushing up on, even now. I was lucky that I was taking a lab class where we weren't allowed calculators the same semester that I took the OAT, so I was already in the habit of thinking in scientific notation and estimating figures.
And don't be nervous about it -- it's not that bad. You've been taking classes all along to help you prepare for it, so just think of the studying you'll be doing as "brushing up" on things you already know. You'll do great! 🙂