You've been misinformed, but that's not surprising given that most optometrists I've met are woefully ignorant when it comes to legal issues. To reiterate, a state regulatory board has no power to prevent you from putting a degree you earned after your name. By doing so, you are "implying" nothing -- you are simply stating the fact that you earned an O.D. degree. On the other hand, if you use the term "optometrist", you very well may be in hot water, because that term may be restricted in your state to people who have passed boards, paid loot to the State Board, and are licensed optometrists. By referring to yourself as an "optometrist" in these jurisdictions, it could be argued that you're implying that you are licensed to practice optometry when you actually are not.
The same holds true for J.D.'s and attorneys. Anyone who has been awarded a J.D. is entitled to put those letters after his or her name. However, in most (if not all) states, they couldn't not refer to themselves as a lawyer or attorney at law without having passed the bar exam.
He's not misinformed at all. It's always better to err on the side of caution. In a strict legal sense, it would NOT be unethical or illegal to append O.D. after your name in some circumstances. HOWEVER, that being said, the OP wanted to know about business cards.
So, if you're Joe Smith and you just graduated from Ferris State University Michigan College of Optometry in May with your O.D. degree and you are awaiting your license, or simply not licensed in your jurisdiction yet, when can you use O.D. after your name?
1) After signing any legal documents; it may be pretentious and stupid, but there is nothing misleading or illegal about signing your name Joe Smith, O.D.
2) Your checks. While this might be stupid and self laudatory, hey, nothing wrong with it.
3) Resumes and CVs. Your name could read Joe Smith, O.D., 200 W. Livernois, Troy, MI 48098, and this would be perfectly acceptable.
4) Teaching/academia. Let's say you get hired by a local nursing school or PA school to teach ocular anatomy/phys for a good chunk of change. Let's also say you have no desire to practice optometry, or maybe you make more teaching than you do practicing (it could happen, right?). You're not licensed. In the classroom, you can be called "doctor" and on your business cards and nameplate, you can be Joe Smith, O.D., without fear of penalty. In this context, you're in no way, shape, or form holding yourself out as an optometrist...you're no different than any PhD or EdD or JD who is also teaching a class.
5) In general social settings, or when making appointments with your physician, dentist, vet, etc., there is nothing wrong with saying "Dr. Smith". If asked, qualify, but you're the patient or client, or in a general social setting, so who cares what people think...if you have it and want to flaunt it, do it. Remember one thing, though, if you're in a social setting and someone approaches you and says "you said you're a doctor, right? We have somone who's having a seizure, can you help?" EVEN if you have some EMS training, you say "I am
not a doctor, I have a degree in optometry!" Always qualify and never offer to help, even if you have some medical first responder training, and say "I'm a doctor, I can help!" Do not place yourself in potential professional liability. No offense, but an OD is in no position to help anyone in need of exigent medical assistance, UNLESS he/she is also an EMT/paramedic licensed by THAT state. IF you're an OD in Michigan and an EMT in Ohio, you can offer help as an EMT, but you should be cautious and assess the situation. In general, use common sense.
As an unlicensed O.D., you are not legally entitled to provide any form of tx, dx, advice, counseling, or optometry-related services to anyone or anything. So, this begs the question, why would you need busness cards? What exactly are you doing that you need a professional business card?
The deciding legal factor here is context. In what context is it acceptable for any unlicensed professional who holds an earned professioanl doctorate to use that title or degree? In the above examples, it's perfectly acceptable, but without a license, and without one of the above situations, do not buy any cards and use your degree; it could be considered solicitation of professional opt services. You could lose your license once you get it or you could be reprimanded, fined, or penalized by the state board for practicing without a license. Why risk it?