Drug Information Portal. U.S. National Library of Medicine. "Relebactam". Drug Information Portal. U.S. National Library of Medicine.
Individuals with the complete form of CSNB (CSNB1) have highly impaired rod sensitivity (reduced ~300x) as well as cone dysfunction. Patients with the incomplete form can present with either myopia or hyperopia. Cause
CSNB is caused by malfunctions in neurotransmission from rod and cone photoreceptors to  bipolar cells in the retina. At this first synapse, information from photoreceptors is divided into two channels: ON and OFF. The ON pathway detects light onset, while the OFF pathway detects light offset. The malfunctions in CSNB1 specifically affect the ON pathway, by hindering the ability of ON-type bipolar cells to detect neurotransmitter released from photoreceptors. Rods, which are responsible for low-light vision, make contacts with ON-type bipolar cells only, while, cones, which are responsible for bright-light vision, make contacts with bipolar cells of both ON an OFF subtypes. Because the low-light sensing rods feed only into the ON pathway, individuals with CSNB1 typically have problems with night vision, while vision in well-lit conditions is spared. In CSNB2, release of neurotransmitter from photoreceptors is impaired, leading to involvement of both ON and OFF pathways. The electroretinogram (ERG) is an important tool for diagnosing CSNB. The ERG a-wave, which reflects the function of the  phototransduction cascade in response to a light flashes, is typically normal in CSNB patients, although in some cases phototransduction is also affected, leading to a reduced a-wave. The ERG b-wave, which primarily reflects the function of ON-bipolar cells, is greatly reduced in CSNB2 cases, and completely absent in CSNB1 cases.