California Code, Business and Professions Code - BPC § 3098

When the holder uses the title of “Doctor” or “Dr.” as a prefix to his or her name, without using the word “optometrist” as a suffix to his or her name or in connection with it, or, without holding a diploma from an accredited school of optometry, the letters “Opt. D.” or “O.D.” as a suffix to his or her name, it constitutes a cause to revoke or suspend his or her optometrist license.