Karl Koller (ophthalmologist)

Karl Koller (December 3, 1857 – March 21, 1944) was an Austrian ophthalmologist who began his medical career as a surgeon at the Vienna General Hospital and a colleague of Sigmund Freud.

Koller introduced cocaine as a local anaesthetic for eye surgery. Prior to this discovery, he had tested solutions such as chloral hydrate and morphine as anaesthetics in the eyes of laboratory animals without success. Freud was fully aware of the pain-killing properties of cocaine, but Koller recognized its tissue-numbing capabilities, and in 1884 demonstrated its potential as a local anaesthetic to the medical community. Koller's findings were a medical breakthrough. Prior to his discovery, performing eye surgery was difficult because the involuntary reflex motions of the eye to respond to the slightest stimuli. Later, cocaine was also used as a local anaesthetic in other medical fields such as dentistry. In the 20th century, other agents such as Xylocaine have replaced cocaine as a local anaesthetic.