the eye was a test case for natural selection; and for Helmholtz, it was a brilliant compromise — a flawed device to a brass and glass instrument-maker, but a structure nonetheless capable of ...

The retina is an extremely complex structure. It's made up of at least ... Whatever light is not absorbed on this return trip passes out of the eye the same way it came in—through the pupil.

Light passes through the eyeball to the retina. There are two main types of light receptors called rods and cones. Rods are more sensitive to light than cones so they are useful for seeing in dim ...