Embodiments of the present invention provide an optical system (100) for imaging a retina through a pupil of an eye (10). The optical system (100) comprises an illumination source (120) for providing light to illuminate the eye (10) via an illumination optical system (140). The optical system further comprises an imaging device (130) for outputting image data corresponding to the retina of the eye (10) over a period of time. Said imaging device (130) is arranged to receive reflected light from the eye (10) via an imaging optical system (150). The optical system (100) further comprises a moveably mounted offner relay (110) arranged to direct light received from the illumination optical system (140) to the eye (10) and to direct reflected light from the eye (10) to the imaging optical system (150). Said offner relay (110) is arranged to move to track a location of the pupil.
