Ophthalmology (, ) is the branch of medicine that deals with the diagnosis, treatment, and surgery of eye diseases and disorders. Ophthalmologists also diagnose systemic (other parts of the body) diseases using changes seen in the eyes.

An ophthalmologist is a physician with an MD or DO degree who undergoes specialty training in medical and surgical eye care. In the United States, following graduation from medical school, one must complete a four-year residency in ophthalmology to become