ON-RESPONSE AND OFF-RESPONSE IN THE PHOTOPIC ELECTRORETINOGRAM IN COMPLETE-TYPE CONGENITAL STATIONARY NIGHT BLINDNESS

We examined the on- and off-responses of the photopic electroretinogra m in patients with complete congenital stationary night blindness. Sta ndard flash electroretinograms as well as those produced in a ganzfeld modified for long-duration light stimuli (500 msec) permitted the sep aration of on- and off-responses in four patients and four normal subj ects. The amplitude and latency of the electroretinogram on- response (a- and b-waves) and off-response (d-wave) in addition to the oscillat ory potentials of the off-response in normal subjects and patients wer e compared. The abnormal on-response was demonstrated in all the patie nts, and the off response with its oscillatory potentials were preserv ed. We showed that the second portion of the off-response (of inner re tinal origin) is normal. If congenital stationary night blindness is a defect of depolarizing bipolar cells, these results preclude input of the depolarizing bipolar cells and support the hyperpolarizing bipola r cells as the cellular origin of the off-response electroretinogram.