The present invention relates to an Illuminating device for an operating microscope in ophthalmic surgery, having at least one light source (151), at least one lens (152, 155), at least one luminous field diaphragm (153), and at least one optical deflector (156), wherein in order to provide an illumination beam path (119) light from the light source (151) is guided through a main objective (107) which is disposed between the deflector (156) and an eye (180) that is to be observed, and on to the eye that is to be observed, wherein a device (154) that can be introduced into the illumination beam path (119) for acting upon the illumination beam path (119) with a structure that comprises transparent and non-transparent or opaque regions such that this structure can be imaged on or close to the retina (180b) of the eye (180) that is to be observed.
