System and device for an observation of an eye (E) comprising: €¢ a light source (LSo) positioned with respect to the eye (E) and configured to emit an illuminating light ray (r_ill) towards the eye (E)； €¢ an optical relay (OR) positioned with respect to the eye (E) and configured to receive an incident light ray (r_inc) resulting from the interaction between the illuminating light ray( r_ill) and the eye (E), wherein – the incident light ray (r_inc) intersects the optical relay (OR) at an intersection point (P_int), and – forms an incidence angle (alpha_inc) with the normal (n_OR) to the optical relay at the point (P_int) in an incidence plane (PI_inc) formed by the incident light ray (r_inc) and the normal n_OR； €¢ a light sensor (LSe) positioned with respect to the optical relay (OR) and configured to receive a deflected light ray(r_def) resulting from the interaction between the incident light ray (r_inc )and the optical relay (OR), wherein – the deflected light ray (r_def) forms a deflection angle (alpha_def) with the normal (n_OR) in a deflection plane (PI_def) formed by the deflected light ray (r_def) and the normal (n_OR)； wherein the incidence angle (alpha_inc) is different from the deflection angle (alpha_def) and the incidence plane (PI_inc) is different from the deflection plane (PI_def)； or the incidence angle (alpha_inc) is equal to the deflection angle (alpha_def) and the incidence plane (PI_inc) is different from the deflection plane (PI_def)； or the incidence angle (alpha_inc) is different from the deflection angle (alpha_def) and the incidence plane (PI_inc) coincides to the deflection plane (PI_def).La présente invention concerne un système et un dispositif pour l'observation d'un œil (E), comprenant une source lumineuse (LSo) pour éclairer l'œil. Le système comprend en outre un réseau de diffraction servant de relais optique (OR) pour recevoir la lumière réfléchie depuis l'œil et pour la dévier vers un capteur de lumière (LSe)
