FIELD: medical equipment.SUBSTANCE: invention relates to medical devices. Apparatus for monitoring one or more surgical parameters of the eye over multiple sessions which are temporally spaced apart and between which the eye of the patient can have moved. Apparatus comprises: camera for taking one or more images of the eye module for determining during a first session said at least one surgical parameter of the eye and its coordinates based on the image taken by said camera in a first coordinate system module for determining during a second session said at least one surgical parameter of the eye and its coordinates based on the image taken by said camera in a second coordinate system module for determining the eye motion in six degrees of freedom between said first and said second session and for determining a coordinate transformation based thereon module for transforming based on said determined eye motion said at least one surgical parameter of the eye and its coordinates from said first coordinate system into said second coordinate system module for quantifying and/or visualizing the change of said at least one surgical parameter of the eye and its coordinates between said first and said second session based on said surgical eye parameter and its coordinates, measured during said second session and said transformed surgical eye parameter and its coordinates measured during said first session. Surgical eye parameters are one or more of the following: implant-related parameters of the eye which are based on an implant which has been surgically placed in the eye of a patient or the location and/or contour of corneal or limbal, or scleral incisions. Surgical eye parameters comprise one or more of the following: k-readings which define the shape of the cornea in terms of rotation ellipsoid parameters line of sight as the line connecting the pupil center and a fixation point of known location corneal chamber depth visual axis of the eye determination whether the eye i
