It comes from the Greek word "ὀφθαλμός" (ophthalmos), meaning "eye." You'll find this root in many medical terms related to the eye, such as:
* Ophthalmology: The branch of medicine dealing with the eye and its diseases.
* Ophthalmologist: A doctor specializing in ophthalmology.
* Ophthalmic: Relating to the eye.
* Ophthalmoplegia: Paralysis of the eye muscles.
* Ophthalmoscope: A device used to examine the interior of the eye.
So, whenever you see "ophthalm" in a word, you can safely assume it's related to the eye in some way.