The evaluation of pupillary function is a keystone in the neuro-ophthalmic assessment of patients. The diagnosis of an afferent or efferent pupillary disorder is crucial in the acquisition of a broad range of diseases of the brain or the peripheral nervous system. This "update" of pupillary disorders covers a major part of clinical conditions eye doctors have to expect in their daily practice. The significance of pupillary evaluation, however, extends far beyond the area of ophthalmology.