For many years, the operative manipulation of the most minute struc tures was frustrated by the limitations of the human eye. With the introduction of the operating microscope by Nylen (1921), fine detailed anatomy was made visible, so that structures could be prepared, pre sented and manipulated. Nylen used the microscope for treating dis eases of the middle ear. In 1946 Perrit in the U. S. A. introduced the operating microscope into the field of ophthalmic surgery. In 1964, Smith, Kunze and Mitchen published reports on their clinical experi ence using the operating microscope in nerve...