Board certification means that an ophthalmologist has taken and passed rigorous examinations which cover all aspects of medical and surgical eye care. These examinations are voluntary. An ophthalmologist does not have to be board-certified to practice. The American Board of Ophthalmology (ABO) is the main certifying body for ophthalmologists in the United States. Medical specialty boards - including the ABO are accredited by an "umbrella" organization that sets standards for certifying physicians.