Figure 8 of Rotov, Mol Vis 2017; 23:416-430.

Figure 8. Schematics of the relationship between the rims of the photoreceptor disks and the plasma membrane. The dashed areas should be emptied by diffusion to close the cGMP-gated ionic channels (CNGCs) in the plasma membrane. l = disc spacing is assumed to be a coarse estimate of the diffusion distance.