Beginning of Essay
is examined by comparing optical designs of the eyes of present day animals and comparing the advantages and disadvantages of each design. One can extrapolate from the eye designs of today that these eyes may have benefited the animals to be able to adapt to the ....

Middle of Essay
.... its structure and function. On a more basic level, we must also have an understanding of basic optical principles. To gain insight into why the eyes of animals have evolved the way that they have, we must also understand the environment in which animals have needed to adapt to. The theory of lens design has two basic models. The convex lens, or plus lens, is known as a converging lens. When light passes through this lens, it is bent toward the optical axis, which is the direction in which the light was traveling, and is generally perpendicular to the optical element. Depending on the power of the lens, the light that passes through it ....