That's great that you're getting a jumpstart in your career choice so early. If you're interested in optometry, I would start by looking at different schools and their prerequisites. As far as I know, a good number of optometry schools require a 4 year degree by the time you start. After narrowing down your top choices, just be sure that you take all of the necessary prereqs. However, it's not enough that you just take the classes: you have to do well in them too.
Throughout college, you might have a change of heart and realize you have a passion for something else: don't be so set on optometry just yet.. it's good to keep an open mind. Remember to enjoy yourself, but still work hard and make good grades. The better your grades, the less stress you have to deal with later on about if you're a competitive applicant.
Even though your GPA plays a substantial role in your application, you also need to show that you're well-rounded, so it's important that you get involved in extracurricular activities, whether it pertains to optometry or not. Also, it helps if you shadow/work at an optometry practice so you at least have some exposure to the profession. It may be a little overwhelming, so I found it extremely helpful to make a timeline (with the help of your college advisor, if you need it) of which classes I needed to take each semester. When the time approaches for you to start your application process (ideally between your third and fourth year of undergrad), have enough self-discipline and organization skills to help you plan ahead in order to have ample time to study and prepare yourself for the OAT.
Because you're still in high school, I would first just focus on taking the necessary classes for the school you're interested in attending. Again, explore your options. Each school will have their prerequisites listed on their website. Good luck!
