Fig. 17. Dark adaptation curves in a patient with Oguchi's disease (filled circles); normal response is shown below. Rod threshold eventually reaches a normal threshold 4 hours after dark adaptation has begun. (Carr RE: Congenital stationary nightblindness. In Heckenlively JR, Arden GB [eds]: Principles and Practices of Clinical Electrophysiology of Vision, p 713. St Louis: Mosby, 1991.)