November of the same year he used it to operate on a patient with chronic otitis who had a labyrinthine fistula. Nylen's microscope was soon replaced by a binocular microscope, developed in 1922 by his colleague Gunnar Holmgren (1875-1954).

Gradually the operating microscope began to be used for ear operations. In the 1950s many otologists began to use it in the fenestration operation, usually to perfect the opening of the fenestra