System for determining a position of a tool-point-of-interest of a tool, relative to an eye-tissue-of-interest, which includes and imager a tool-tracker and a processor. The imager acquires an image of a tissue-reference-marker. The tool-tracker determines information relating to the P&O of the tool in a reference-coordinate-system. The imager and the tool-tracker are in registration with the reference-coordinate-system. The processor determines the position of the tissue-reference-marker in the reference-coordinate-system, according to the acquired image of the tissue-reference-marker. The processor determines the P&O of the eye-tissue-of-interest in the reference-coordinate-system according to at least the position of the tissue-reference-marker and a relative position between the tissue-reference-marker and the eye-tissue-of-interest. The relative position is pre-determined from a stored-3D-model. The processor determines the position of a tool-point-of-interest in the reference-coordinate-system from the P&O of the tool in the reference-coordinate-system. The processor also determines a relative position between the tool-point-of-interest and the eye-tissue-of-interest.