An eye registration system comprising: a first diagnostic device; a surgery device; and a computing device, the eye registration system being configured for: obtaining a first initial reference eye image by the first diagnostic device and defining a reference coordinate system; obtaining a second eye image by the surgery device, said second eye image being obtained in a pre-surgery phase, wherein the eye has no suction ring being placed on it when said second image is taken; performing, by the computing device, a first registration between said first initial reference eye image and said second eye image to obtain a first registration result; obtaining a third eye image by said surgery device; performing, by the computing device, a second registration between said second eye image and said third eye image to obtain a second registration result; combining, by the computing device, said first and second registration results to obtain a combined registration result to thereby obtain a registration between said first initial reference eye image and said third eye image, wherein said first initial reference eye image and said third eye image are taken under significantly different eye conditions which can negatively affect a direct registration between said first initial reference eye image and said third image, wherein said different eye conditions comprise the eye having no suction ring being placed on it when said first initial reference eye image is taken and the eye having a suction ring being placed on it when the third image is taken, wherein the computing device is configured to perform the registration by identifying one or more eye features in the two eye images, which are to be registered to thereby determine the coordinate relationship between the two pictures; the computing device is configured to use limbus and sclera features for registering the first initial reference eye image and the second eye image; and the computing device is configured to use iris and pupil features for registering the second eye image and the third eye image. a first diagnostic device; a surgery device; and a computing device, obtaining a first initial reference eye image by the first diagnostic device and defining a reference coordinate system; obtaining a second eye image by the surgery device, said second eye image being obtained in a pre-surgery phase, wherein the eye has no suction ring being placed on it when said second image is taken; performing, by the computing device, a first registration between said first initial reference eye image and said second eye image to obtain a first registration result; obtaining a third eye image by said surgery device; performing, by the computing device, a second registration between said second eye image and said third eye image to obtain a second registration result; combining, by the computing device, said first and second registration results to obtain a combined registration result to thereby obtain a registration between said first initial reference eye image and said third eye image, wherein said first initial reference eye image and said third eye image are taken under significantly different eye conditions which can negatively affect a direct registration between said first initial reference eye image and said third image, wherein said different eye conditions comprise the eye having no suction ring being placed on it when said first initial reference eye image is taken and the eye having a suction ring being placed on it when the third image is taken, wherein the computing device is configured to perform the registration by identifying one or more eye features in the two eye images, which are to be registered to thereby determine the coordinate relationship between the two pictures; the computing device is configured to use limbus and sclera features for registering the first initial reference eye image and the second eye image; and the computing device is configured to use iris and pupil features for registering the second eye image and the third eye image.