The retina of a dog has two layers. The outermost layer is a protective and nourishing layer to the inner nerve layer. This inner layer is what receives the light impulses. This inner layer is comprised of cones and rods. Rods are what is used to see black and white. The cones are what interpret color. Until the last few decades we used to think that dogs did not possess cones as humans do and so they could not see colors.
Today we know that dogs inner layer of the retina possess cones although about 90% fewer than humans. This is why dogs see better shades of black and white than do humans, because they have a geater percentage of rods. It is also why dogs can indeed see color but not with the clarity, distinction and diversity of the human eye. In addition dogs have a tapetum lucidum, which reflects light back through the retina giving a dog much greater capability to see at night. In fact, the tapetum lucidum is what makes a dogs eyes "glow" when you see them in low light.
The retina is sensitive and delicate. Hence, it sits in a protective socket and is only open in the front. Dogs with bulging eyes are more prone to damaging the retina. Owners hould be aware of their pets eyes and make sure they are protected. Riding in the back of trucks and sticking heads out the window are invitiations for problems.
Care for your dogs eyes and next time you wear pink with red...remember, your dog might be able to identify your fashion error! (Even though, I somewhat like pink and red together). :) :)
