I think an MBA can be helpful if you make it helpful. If you graduate and just go and find "a job" like all your other non-MBA classmates, then no it's possible that it won't necessarily help you. Could it be a tie-breaker between you and such classmates? I would say for sure.
As for making it helpful, if you have a natural interest in business and finance, I can't see why you couldn't leverage it into something interesting/useful. My particular "concern" would be the timeliness of you getting an MBA now. If you got an MBA say after 10-15 years of practice, because you were getting bored and wanted something else to do (e.g. exploring a 2nd career), then at that point perhaps an MBA would open doors. But coming out with an MBA and an OD just as you are getting started, you won't even have your feet wet with practice experience, so again, it COULD be useful if you make it, but it won't by itself do much if you don't have an interest in the actual MBA material/knowledge, and "only" practice optometry. If you practice for 10-15 years, then at that time, start investigating 2nd careers, then at that point I'm not sure how up-to-date/relevant your MBA would be.
Anyways - not speaking from experience. Just random thoughts.