This study was an evaluation of the effectiveness of the Callisto eye image-guided, markerless system (Carl Zeiss Meditec AG, Jena, Germany) in toric intraocular lens (IOL) positioning.The results of a novel, markerless, alignment system used for IOL positioning were analyzed in this retrospective study. Preoperatively, reference image registration was performed with the IOLMaster 700 biometer (Carl Zeiss Meditec AG, Jena, Germany) and transferred to the Callisto eye system, which was used in conjunction with an Opmi Lumera 700 microscope (Carl Zeiss Meditec AG, Jena, Germany). Using the Callisto Z Align technology, a toric IOL was aligned precisely with the steep axis. One day after surgery, the pupil was fully dilated and a thin slit was placed on the marker of the toric IOL and the angle was measured using an axis calculator smartphone application. The degree of the measured angle and the preoperatively determined angle were compared.Sixty eyes of 46 patients were included. The difference in the absolute angle between the intended and the postoperative (at day 1) axes was a mean of 2.71±1.64°.The Callisto eye image-guided, markerless system successfully provided assistance in precisely positioning the toric IOL.