A system configured for verifying, by a user, a proposed registration during ophthalmic surgery, the system comprising: a processor; and a non-transitory computer-readable medium accessible to the processor containing instructions executable by the processor for: acquiring, from a photosensor, an intra-operative image (106; 201) of a patient's eye under magnification by a microscope; retrieving, from the non-transitory computer-readable medium, a pre-operative reference image (101; 202; 307) of the patient's eye, wherein the limbus of the pre-operative image (101; 202; 307) of the patient's eye has a center; performing a registration process to provide a proposed registration of the pre-operative reference image (101; 202; 307) of the patient's eye and the intra-operative image (106; 201) of the patient's eye; overlaying the pre-operative reference image (101; 202; 307) and the intra-operative image (106; 201) to provide a merged image having the proposed registration, wherein the merged image is viewable by the user; adjusting the transparency of at least one of the pre-operative reference image (101; 202; 307) and the intra-operative image (106; 201), so that the pre-operative reference image (101; 202; 307) and the intra-operative image (106; 201) are simultaneously viewable in the merged image by the user; and rotating the viewable pre-operative reference image (101; 202; 307) relative to the viewable intra-operative image (106; 201) comprised in the viewable merged image, wherein the rotating is centered on the center of the limbus of the patient's eye in the pre-operative reference image (101; 202; 307), and wherein the rotating comprises a series having a plurality of viewable alternating clockwise and anticlockwise rotations; thereby allowing the user to verify a proposed registration during ophthalmic surgery, characterised in that the series has a first viewable rotation having a first angle; and following the first viewable rotation, each successive viewable rotation of the series has a smaller angle. a processor; and a non-transitory computer-readable medium accessible to the processor containing instructions executable by the processor for: acquiring, from a photosensor, an intra-operative image (106; 201) of a patient's eye under magnification by a microscope; retrieving, from the non-transitory computer-readable medium, a pre-operative reference image (101; 202; 307) of the patient's eye, wherein the limbus of the pre-operative image (101; 202; 307) of the patient's eye has a center; performing a registration process to provide a proposed registration of the pre-operative reference image (101; 202; 307) of the patient's eye and the intra-operative image (106; 201) of the patient's eye; overlaying the pre-operative reference image (101; 202; 307) and the intra-operative image (106; 201) to provide a merged image having the proposed registration, wherein the merged image is viewable by the user; adjusting the transparency of at least one of the pre-operative reference image (101; 202; 307) and the intra-operative image (106; 201), so that the pre-operative reference image (101; 202; 307) and the intra-operative image (106; 201) are simultaneously viewable in the merged image by the user; and rotating the viewable pre-operative reference image (101; 202; 307) relative to the viewable intra-operative image (106; 201) comprised in the viewable merged image, wherein the rotating is centered on the center of the limbus of the patient's eye in the pre-operative reference image (101; 202; 307), and wherein the rotating comprises a series having a plurality of viewable alternating clockwise and anticlockwise rotations; acquiring, from a photosensor, an intra-operative image (106; 201) of a patient's eye under magnification by a microscope; retrieving, from the non-transitory computer-readable medium, a pre-operative reference image (101; 202; 307) of the patient's eye, wherein the limbus of the pre-operative image (101; 202; 307) of the patient's eye has a center; performing a registration process to provide a proposed registration of the pre-operative reference image (101; 202; 307) of the patient's eye and the intra-operative image (106; 201) of the patient's eye; overlaying the pre-operative reference image (101; 202; 307) and the intra-operative image (106; 201) to provide a merged image having the proposed registration, wherein the merged image is viewable by the user; adjusting the transparency of at least one of the pre-operative reference image (101; 202; 307) and the intra-operative image (106; 201), so that the pre-operative reference image (101; 202; 307) and the intra-operative image (106; 201) are simultaneously viewable in the merged image by the user; and rotating the viewable pre-operative reference image (101; 202; 307) relative to the viewable intra-operative image (106; 201) comprised in the viewable merged image, wherein the rotating is centered on the center of the limbus of the patient's eye in the pre-operative reference image (101; 202; 307), and wherein the rotating comprises a series having a plurality of viewable alternating clockwise and anticlockwise rotations; thereby allowing the user to verify a proposed registration during ophthalmic surgery, characterised in that the series has a first viewable rotation having a first angle; and following the first viewable rotation, each successive viewable rotation of the series has a smaller angle.