Final answer:
The device that uses ultrasonic energy to fragment the lens during extracapsular cataract extraction is the D. phacoemulsifier. This device employs ultrasonic vibrations to emulsify the lens for removal and replacement with an artificial lens.
Step-by-step explanation:
The device that uses ultrasonic energy to fragment the lens in extracapsular cataract extraction is known as a D. phacoemulsifier.
This medical device utilizes ultrasonic vibrations to break up the cloudy lens, which is then suctioned out of the eye to allow for the insertion of an artificial intraocular lens. During this procedure, the rest of the lens capsule is left intact.
Other devices listed, such as the keratome, ocutome, and cystotome, have different uses. For instance, a keratome is a surgical instrument used to cut the cornea, commonly during procedures like LASIK, as mentioned in the provided context.
However, for the specific purpose of fragmenting the lens via ultrasound in cataract surgery, the phacoemulsifier is the appropriate tool.