Systems, methods and apparatus for tracking changes in an ocular scene

Systems, methods and apparatus are provided through which in some aspects an ocular scene is imaged and changes in the ocular scene relative to a calibration image, are tracked. In one aspect, an imaging instrument includes an eyepiece, a light source operable to project light, an imaging system operable to image an ocular scene; and a processing system operable to receive a set of calibration images, and further operable to capture an image of the imaged ocular scene associated with a calibration image. In another aspect, a method to track changes in an ocular scene includes receiving a set of calibration images, receiving a set of landmarks on each calibration image, capturing a set of images of an ocular scene, associating each captured image with a calibration image, and detecting landmarks on each captured image wherein each detected landmark corresponds to a landmark on the associated calibration image.