Remember, you're going be in a medical service profession where a large percentage of your patients will be conservative & elderly.
Piercings & visible tattoos will have a negative effect on your income, how much, may depend on where you practice. I would never hire an OD/staff member that I know would offend a large % of my patient base.
I notice the advice of "it's no big deal" comes from students and not practicing OD's.
You have a right to display your individualism, but patients have the right to choose another doctor because of how you express it.