Abstract: Optical designating device, especially for use in microsurgery, comprising a tool-carrier stage (2) integral with the optical instrument (1), supporting at least one light source (4, 5) for emitting a light beam (6, 7), said light source (4, 5) being offset in relation to the optical axis (10) of the optical instrument (1). The orientation of the light source (4, 5) in relation to the optical axis (10 ) of the microscope is determined in order to aim the light beam (6, 7) at a target point (15).

Abstract: Computer-assisted microsurgery equipment, of the type including an articulated tool support, with one of the ends being integral with a fixed reference system R.sub.c. The system comprises cameras for determining the tool coordinates in said fixed reference system R.sub.c, and an image data base wherein are recorded images from an imaging system in the image reference system R.sub.i. The inventions characterized by having at least two sensors integral with the fixed reference system R.sub.c supplying an electrical signal depending on the patient reference position R.sub.p in the fixed reference system R.sub.c, and a computer for matching the tool reference system R.sub.o with the patient reference system R.sub.p and the image reference system R.sub.i according to data from the bidimensional sensor, cameras for determining the coordinates of the tool in the fixed reference system R.sub.c and data from the image base.