Operation
Although there are many meanings to the word 'operation', in medicine it refers to a surgical procedure.
To put matters more formally, an operation is 'an act or series of acts performed upon the body with the hand alone or by means of an instrument', the aim being 'to remedy deformity or injury, cure or prevent disease, or relieve pain.' There are many operations named after persons.
They range from A to Z: from the Abbe operation (on the lip) to the Ziegler operation (on the iris of the eye).