A positioning unit for positioning an optical unit in an optical path of a microscope between a microscope lens and in front of an eye to be examined includes a connection device coupling the positioning unit to the microscope. The positioning unit includes an accommodating device configured to adapt an ophthalmoscopic lens that serves to examine an ocular fundus to the positioning unit as an optical element of the optical unit. The positioning unit includes a positioning device to move the ophthalmoscopic lens relative to the microscope in the longitudinal direction of the optical path. The accommodating device presents an adjusting means for displacing the ophthalmoscopic lens in an adjusting plane that runs orthogonally relative to the optical path of the microscope.
