Rods
- Rods provide black and white vision, and permits vision in dim light.
- Rods enable night vision because they are much more sensitive to light than cones are.
- Rhodopsin is the light sensitive pigment in rods
- The rhodopsin is bleached when exposed to bright light:
- Rods then cannot send nerve impulses to the brain under very bright conditions
- In the absence of light rhodopsin is regenerated, so that a person can see in the dark
- Rhodopsin is a derivative of vitamin A. This is why a person with vitamin A deficiency is unable to see in dim light
- Rods are more sensitive when detecting movement than cones are
- Rods are responsible for for peripheral vision as they are absent from the fovea, but present at high densities a short distance from the fovea.