The present invention provides a full body harness which can include curved webbing, a spreading back pad andor leg buckles which improve the comfort, use and performance of the harness. The body unit includes photographing optical system for photographing a fundus Fu to be observed. The first liquid filter element forms a mixing chamber in a center of the first liquid filter element for mixing the liquid filtered by the first liquid filter element and the liquid filtered by the second liquid filter element. The at least one sensor generates a signal corresponding to the sensed parameter.