Efferent pupillary defect A lesion occurs in the oculomotor nerve's pupilloconstrictor nerve fibers. Results in dilation of the ipsilateral pupil (Due to unattended effect of the intact sympathetic supply). There will be failure of constriction of the pupil to light, light reflex will be preserved in the other eye. Light shone into the contralateral eye will elicit a normal direct response. Afferent pupillary defect Failure of constriction of either pupil to light shone into the affected eye If the visual system is normal in one eye, light shone will produce a normal direct pupillary reponse and also a consensual in the other eye.