Attachment module for a microscope, having an ophthalmoscopic lens (142 242 342) and an inverting device (140 240 340) for inverting an image of an object (143 243 343) that is to be observed generated by means of the ophthalmoscopic lens, wherein the inverter device comprises at least four deflection surfaces (146a, 146b, 146c 246a, 246b, 246c 346a, 346b, 346c, 346d) by means of which observation beam paths (102) which emanate from the object to be observed can be introduced into a main objective (110) of the microscope, at least two deflection surfaces being planar and at least two further deflection surfaces being non-planar, particularly spherical or in the shape of free-form surfaces.
