Congenital stationary night blindness (CSNB) variant caused by a disruption in the steps of inactivation of rod phototransduction associated with fundus discoloration and abnormally slow dark adaptation after light exposure, along with characteristic electroretinographic (ERG) abnormalities.
M/C cause of congenital stationary night blindness (CSNB) in the Japanese population
The disease was first reported by Oguchi in 1907 as a variant form of congenital stationary night blindness (CSNB) and was later characterized phenotypically by Mizuo in 1913 , who demonstrated the Mizuo-Nakamura phenomenon in affected individuals. In this test after 2–3 h of dark adaptation of the eyes, the diffused yellow/grey discoloration of the fundus returns to normal, along with the reappearance of rod function. The discoloration of the fundus reappears shortly after reexposure to light. Oguchi disease has been shown to be more common in the Japanese population compared to other populations. In addition to the typical Oguchi disease, variant forms have also been reported without the typical Mizuo-Nakamura phenomenon and variable fundus appearances and ERG patterns.
Rhodopsin kinase (GRK1) and Arrestin (SAG) are two genes which act in sequence to deactivate rhodopsin to stop the phototransduction cascade. Photoactivated rhodopsin is recognized by rhodopsin kinase, which phosphorylates serine and threonine residues near rhodopsin’s carboxy terminus. Arrestin then forms a complex with phosphorylated rhodopsin, and this complex prevents further interaction of the activated rhodopsin with transducin. Mutations in either the rhodopsin kinase gene or the arrestin gene cause a recessive form of stationary night blindness called Oguchi’s disease.
Static nyctalopia (night vision) since childhood
Preservation of vision in bright light.
Golden or gray-white discoloration of the fundus that disappears in the dark-adapted state and reappears shortly after the onset of light.
Negative waveform morphology with non-recordable single flash rod response (CHARCTERISTIC)