Fig. 3.

Rod and cone system responses from a patient with unilateral CRAO (A–F), and cone-driven responses from a male patient with NYX deletion (G–I). Stimuli are as in Fig. 2, with the same method of rod and cone isolation. (A–C) Rod system–isolated responses from a patient with CRAO. In the CRAO eye, inner retinal layers have degenerated but photoreceptors are intact: The a-waves are similar between eyes, reflecting intact rods, but b-waves differ, due to loss of inner retinal neurons. (D–F) Cone system responses from the same patient. As well as expected differences in b-waves due to loss of inner retinal layers, a-wave amplitudes also differ markedly, consistent with a postreceptoral origin of a substantial fraction of the cone-driven a-wave. (G–I) Cone-driven responses to the same flash strengths from a patient with selective loss of ON-bipolar cell signals. The b-wave is severely attenuated in the responses shown (particularly brighter flashes), indicating that the normal b-wave elicited by these stimuli in healthy individuals is from the ON pathway. The dashed trace shows standard LA 3 response in this patient (same stimulus as in Fig. 1 G–I): A b-wave is present, indicating that for this stimulus, OFF-bipolar cells do contribute to the b-wave.