title: ERG rod a-wave in Oguchi disease.
abstract: We analyzed the change in the ERG rod a-wave waveform during the course of dark adaptation in two patients with Oguchi disease. Two Japanese patients showed a homozygous arrestin 1147delA mutation. Scotopic flash ERGs were recorded after different periods of dark adaptation. ERG rod a-waves were obtained after subtraction of the cone ERG contribution. The rod a-waves were fitted with a model of the rod receptor signal. The parameters, Rm(p3) (maximum a-wave amplitude) and S (sensitivity) were calculated. Longer periods in the dark produced larger rod a-wave but only to the first flash presented. The amplitude of the response to subsequent flashes was essentially independent of the period of dark adaptation. Rm(p3) increased with advance of dark adaptation. However, S was nearly constant. Our results suggest that the cause of delayed dark adaptation is not to be sought in the activation of phototransduction process or the regeneration of rhodopsin per se but rather in the deactivation process of the phototransduction cascade.
authors.affiliation: Division of Ophthalmology and Visual Science, Graduate School of Medical and Dental Sciences, Niigata University, 1-757 Asahimachi, Niigata 951-8510, Japan. usuit@med.niigata-u.ac.jp
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Usui
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Tanimoto
authors.forename: Satoshi
authors.initials: S
authors.lastname: Ueki
authors.forename: Mineo
authors.initials: M
authors.lastname: Takagi
authors.forename: Shigeru
authors.initials: S
authors.lastname: Hasegawa
authors.forename: Haruki
authors.initials: H
authors.lastname: Abe
authors.forename: Keigo
authors.initials: K
authors.lastname: Sekiya
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Nakazawa
mesh_terms: D003623:Dark Adaptation; D004596:Electroretinography; D005260:Female; D006801:Humans; D008875:Middle Aged; D009755:Night Blindness / Q000503:physiopathology*; D017948:Retinal Rod Photoreceptor Cells / Q000503:physiopathology*; D014785:Vision, Ocular