A cataract surgical procedure which uses an ultrasonic vibration to shatter and break up a cataractous lens, making it easier to remove. The vibration is delivered by an irrigation-aspiration instrument. In a survey of ASCRS members in 1994, 86% preferred the phacoemulsification cataract removal technique over the extracapsular cataract extraction technique. The technique was invented by Charles D. Kelman, MD, and was first published in 1967.