Abstract
Purpose: :
Afferent pupillary defect is a sine qua non of asymmetric optic nerve function. It may also occur with advanced retinal disease. Post chiasmal afferent pupillary defects have been recognized as a manifestation of optic tract involvement. When unassociated with visual field defects, a post chiasmal afferent still may be produced by involvement of the pupillary tract or midbrain. These have been felt to be rare.
Methods: :
A retrospective study of patients coded as suspected pupillary tract disturbance seen between 1985 and 2010 at the University of Virgina. Information regarding the patient’s age, sex, visual acuity, presence and size of afferent pupillary defect, visual field defect, optical coherence tomography, motility disturbances, and imaging studies were gathered.
Results: :
Sixty charts suspected of pupillary tract defects were examined. Thirty-one of these patients were found to have an APD not attributable to optic nerve disease, retinal disease, and optic tract disease. Of the 31 patients, 12 patients had afferent pupillary defects with no visual field defects and no motility problems. Ten patients demonstrated APD with no visual field defect, but the presence of motility problems attributed to the area of the midbrain. Motility defects include fourth nerve palsy and skew deviation. Ten patients did have homonymous defects with evidence of pathology affecting the temporal or occipital lobe but without thinning on OCT or evidence of optic atrophy.
Conclusions: :
Pupillary tract and midbrain afferent pupillary defects are not rare. They may be an unrecognized cause of small afferent pupillary defects that are otherwise discounted. In patients with midbrain pathology, careful assessment for subtle asymmetric pupillary response with filter stress may confirm pupillary pathway abnormalities. Similarly subtle APDs may be due to unrecognized midbrain pathology.
Keywords: pupillary reflex • neuro-ophthalmology: diagnosis