Rhodopsin vision in the dark. Several closely related opsins differ only in a few amino acids and in the wavelengths of light that they absorb most strongly. Humans have eight other opsins besides rhodopsin, as well as cryptochrome (light-sensitive, but not an opsin). The photopsins are found in the cone cells of the retina and are the basis of color vision. They have absorption maxima for yellowish-green (photopsin I), green (photopsin II), and bluish-violet (photopsin III) light. The remaining opsin, melanopsin, is found in photosensitive ganglion cells and absorbs blue light most strongly. In rhodopsin, the aldehyde group of retinal is
Retina Retina The retina is the innermost, light-sensitive layer, or "coat", of shell tissue of the eye of most vertebrates and some molluscs. The optics of the eye create a focused two-dimensional image of the visual world on the retina, which translates that image into electrical neural impulses to the brain to create visual perception, the retina serving much the same function as film or a CCD in a camera. The retina consists of several layers of neurons interconnected by synapses. The neural retina refers to the three layers of neural cells (photo receptor cells, bipolar cells, and ganglion cells) within