Possibilities of simultaneous analysis of phasic pupillary light reflex and visual evoked potentials

A report of first results of a simultaneous analysis of the phasic pupillary light reflex and visual evoked potentials (VEP). It is shown that combination of pupillography with VEP analysis can be of some use in the diagnosis of conductive defects of the optic nerve (e.g. optic neuritis). Furthermore, the simultaneous analysis allows distinction between subclinical disturbances of the afferent and efferent arcs of the pupillary light reflex. Assuming a lesion of the afferent arc secondary to damage to the optic nerve, an increase of both the pupillomotor and the VEP latencies is seen. With lesions of the efferent arc (e.g. in the case of a third nerve palsy) only the pupillomotor latency is altered. Potentialities and disadvantages of the method are discussed.