Cal. Bus. & Prof. Code § 3098

When the holder uses the title of “Doctor” or “Dr.” as a prefix to his name, without using the word “optometrist” as a suffix to his 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 name, it constitutes a cause to revoke or suspend his certificate of registration.