Method for 3D high-resolution localization microscopy, in which, - in an excitation step, a specimen is illuminated with excitation radiation to excite fluorescent markers in the specimen to emit light, - in an imaging step, the specimen is imaged into an individual image along an imaging direction by means of an imaging optical unit (3, 14), wherein the individual image contains imaged presentations of the luminous fluorescent markers and the imaging optical unit has a focal plane and an optical resolution, - the excitation step and the imaging step are repeated multiple times and in this way a plurality of individual images are generated, wherein the excitation steps are performed such that at least for some of the luminous fluorescent markers the imaged presentations thereof are isolated in each of the individual images, - in the generated plurality of individual images, in each case a location indication of the corresponding fluorescent marker is ascertained from the isolated imaged presentations of the luminous fluorescent markers, the location indication having an accuracy going beyond the optical resolution, - a high-resolution overall image is generated from the location indications thus ascertained, characterized in that - the excitation radiation is radiated as a first light sheet (4, 4.1), which has an intensity distribution (17, 17.1) along the imaging direction that is asymmetric with respect to the focal plane, into the specimen, and - in the individual images, the isolated imaged presentations of the luminous fluorescent markers are analysed with respect to their outline shape and an indication relating to the distance of the corresponding fluorescent marker from the focal plane is derived from the outline shape. - in an excitation step, a specimen is illuminated with excitation radiation to excite fluorescent markers in the specimen to emit light, - in an imaging step, the specimen is imaged into an individual image along an imaging direction by means of an imaging optical unit (3, 14), wherein the individual image contains imaged presentations of the luminous fluorescent markers and the imaging optical unit has a focal plane and an optical resolution, - the excitation step and the imaging step are repeated multiple times and in this way a plurality of individual images are generated, wherein the excitation steps are performed such that at least for some of the luminous fluorescent markers the imaged presentations thereof are isolated in each of the individual images, - in the generated plurality of individual images, in each case a location indication of the corresponding fluorescent marker is ascertained from the isolated imaged presentations of the luminous fluorescent markers, the location indication having an accuracy going beyond the optical resolution, - a high-resolution overall image is generated from the location indications thus ascertained, - the excitation radiation is radiated as a first light sheet (4, 4.1), which has an intensity distribution (17, 17.1) along the imaging direction that is asymmetric with respect to the focal plane, into the specimen, and - in the individual images, the isolated imaged presentations of the luminous fluorescent markers are analysed with respect to their outline shape and an indication relating to the distance of the corresponding fluorescent marker from the focal plane is derived from the outline shape.