Adaptation (eye) opsin photopigment. The various cone cells are maximally sensitive to either short wavelengths (blue light), medium wavelengths (green light), or long wavelengths (red light). Rod photoreceptors only contain one type of photopigment, rhodopsin, which has a peak sensitivity at a wavelength of approximately 530 nanometers which corresponds to blue-green light. A minor mechanism of adaptation is the pupillary light reflex, adjusting the amount of light that reaches the retina. In response to varying ambient light levels, rods and cones of eye function both in isolation and in tandem to adjust the visual system. Changes in the sensitivity of rods and
Retina density of rods converging on single bipolar cells. Since its cones have a much lesser convergence of signals, the fovea allows for the sharpest vision the eye can attain. Though the rod and cones are a mosaic of sorts, transmission from receptors, to bipolars, to ganglion cells is not direct. Since there are about 150 million receptors and only 1 million optic nerve fibres, there must be convergence and thus mixing of signals. Moreover, the horizontal action of the horizontal and amacrine cells can allow one area of the retina to control another (e.g. one stimulus inhibiting another). This inhibition