Walsh & Hoyt: Pupillary Examination

Examination of the pupils is an essential part of the afferent ystem evaluation. Pupil size for each eye should be noted, as should the magnitude and latency of the direct and consensual responses to light and near stimulation. The presence of a relative afferent pupil defect (RAPD) is the hallmark of a unilateral afferent sensory abnormality or bilateral asymmetric visual loss. The etiology is usually an optic neuropathy, but other abnormalities such as a central retinal artery occlusion, retinal detachment, or a large macular scar may be responsible. In the case of a retrobulbar optic neuropathy with a relatively normal-appearing fundus examination, the RAPD may be the only objective sign of anterior visual pathway dysfunction.