Czech-born American ophthalmic surgeon whose introduction of cocaine as a surface anesthetic in eye surgery (1884) inaugurated the modern era of local anesthesia.

Koller was an intern and house surgeon at the Vienna General Hospital when his colleague Sigmund Freud, attempting to cure a friend of morphine addiction, asked him to review and investigate the general physiological effects of cocaine as a possible remedy. His experimental results convinced Koller that cocaine could be used as a local anesthetic in eye surgery, for which general anesthesia had proved to be unsuitable. He immigrated to the United States in 1888, where he maintained a successful ophthalmology practice in New York City until his death.