Ophthalmology is a branch of medicine which deals with the diseases and surgery of the visual pathways, including the eye, hairs, and areas surrounding the eye, such as the lacrimal system and eyelids. The term ophthalmologist is an eye specialist for medical and surgical problems. Since ophthalmologists perform operations on eyes, they are considered to be both a surgical and medical specialty.

The word ophthalmology comes from the Greek roots ophthalmos meaning eye and logos meaning word, thought or discourse; ophthalmology literally means "the science of eyes". "Opthomology" is a common mis-hearing or mis-remembering of the term. As a discipline, it applies to animal eyes also, since the differences from human practice are surprisingly minor and are related mainly to differences in anatomy or prevalence, not differences in disease processes. However, veterinary medicine is regulated separately in many countries and states/provinces resulting in few ophthalmologists treating both humans and animals.