History of lasers in endourology.

While the theory of "stimulated emission," which later led to the development of the laser, was first proposed by A. Einstein in 1917, it was not until 1960 that the American physicist T. Maiman achieved the first laser emission using a ruby crystal as the active medium. In 1966, R.L. Parsons reported the first in vivo use of a laser in urology, in the context of destroying a canine bladder tumor previously approached via open surgery. In 1968, W.P. Mulvaney and C.W. Beck succeeded in fragmenting calculi in vitro using a ruby laser. Research conducted during the 1980s marked a crucial milestone in the evolution of laser technology and its use in urology. Various innovative applications were explored, with varying degrees of success. Today, only safe and effective lasers have remained. The most commonly used lasers in modern urology include Ho:YAG, continuous and pulsed Tm:YAG, thulium fiber, GreenLight KTP or LBO, and diode lasers. Thanks to their diversity and specific properties, lasers now occupy a central place in the urologist's equipment, combining versatility and efficacy. They are currently employed in the treatment of a broad spectrum of conditions, including urolithiasis, benign prostatic hyperplasia, urothelial tumors (of both the upper urinary tract and bladder), urethral and ureteral strictures, and ureteropelvic junction obstruction.