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).
