An ophthalmologist is a medical doctor who specialises in eye and vision care. Ophthalmologists differ from optometrists and opticians in their levels of training and in what they can diagnose and treat. As a medical doctor who has completed 5 years of medical school and at least 9 years of additional medical training, an ophthalmologist is licensed to practice medicine and surgery. An ophthalmologist diagnoses and treats all eye diseases, performs eye surgery and prescribes medication to correct vision problems. Many ophthalmologists are also involved in scientific research on the causes and cures for eye diseases and vision disorders.