Marcus Gunn pupil in a possible case of unilateral retinitis pigmentosa

A possible case of unilateral retinitis pigmentosa (RP) is reviewed. The electrodiagnostic and clinical findings are discussed, with perspective given to alternative diagnoses. A review of the literature is included to show the controversy which clouds a positive diagnosis of unilateral RP. A co-existing Marcus Gunn pupil is defined and discussed in relation to unilateral RP-like processes.