Your pursuit is to be an optometrist, so I would highly recommend you to shadow or work for an optometrist so that you not only gain knowledge of the profession but so that you can get a glimpse of how your life will be in the future as an optometrist.
As for the ophth offer:
First, try to find out what your responsibilities are as a volunteer with that ophthalmologist. If it is just filing charts, then I wouldn't take it. However, if there is an optometrist there, I would only take it to take advantage of that situation by asking the optometrist if i can shadow him/her. While youre at it, i would also ask the ophthalmologist if i can shadow him/her as well... That way, you can see the difference between both professions. 👍
If there's no optometrist, (and you can't find anyone to shadow) try getting involved with the oncampus optometry club. They should have a list of volunteer/intern/job offers.
As for me..i worked under the ophthalmology department at the Shiley Eye Center - UCSD (during my undergrad years) just to get my foot in the door. I gained so much knowledge about ocular diseases, their treatments, and not to mention the amazing shadowing experiences with all the optometrists there. 🙂
I encourage you to really try to put yourself out there to grasp the fullness of this profession.. I tried to volunteer/intern/shadow/work at different optometric facilities: An eye clinic with both ophth and opt., a visual therapy practice, private practice, lions optometric vision clinic (for those who couldn't afford comprehensive eye exams), peds on the Eye Mobile for Children, and etc. Just remember to really learn from every experience that you encounter and take advantage of all the resources that that facility has to offer.
sorry its so long but ... GOOD LUCK! I hope you enjoy the time you have in learning about optometry.. but who knows.. you may like ophthalmology! its better to find out now than later! right? 😛