Radial Keratotomy in the 1990s and the PERK Study

When radial keratotomy was introduced into the United States, the procedure was performed using razor blade fragments whose extension was determined by sighting on a linear scale block; up to 24 or more incisions of various length per eye were used. As with any new procedure, significant complications occurred. The technique was declared "a risky procedure of unproven long-term success."1The Prospective Evaluation of Radial Keratotomy (PERK) Study was begun in March 1982 as a nine-center trial with 10 participating surgeons that was designed to determine the outcome of a single standardized technique for simple (no astigmatism) myopia.2About the time the PERK Study began, current surgical procedures were just being applied by the majority of radial keratotomy surgeons (diamond blades, ultrasonic measurement of corneal thickness, reduction of the length and number of incisions to ⩽16).3In this issue ofThe Journal, Waring and coworkers4provide