Eye

The eyes are responsible for the detection of light and its transformation to the neuronal signals transmitted to the visual centers of the brain. The eye globe is enveloped in a fibrous corneoscleral layer. The anterior portion includes a translucent surface called the cornea, while the rest is made up of sclera, a white-colored fibrous layer to which the outer eye muscles are attached. The front of the cornea is covered with a non-keratinized stratified corneal epithelium. Underneath the corneoscleral coat lies the choroid, a layer containing blood and lymphatic vessels. Its main function is to provide nutrients to the cells of the eye. Light enters the eye via the pupil, which is a round opening surrounded by the iris. The iris consists of a pigmented fibrovascular layer that allows for the contraction or dilation of the pupil, as well as a layer of pigmented epithelial cells. The size of the pupil affects the amount of light that enters the eye. Light is refracted by the lens, a transparent disc suspended by ciliary muscle fibers. Elongated fiber cells are the predominant component of the lens while the anterior side is lined with epithelial cells. The refracted light is focused onto the retina, the innermost layer of the eye, which transforms light into nerve signals that are then transmitted by the optical nerve to the brain. The space between retina and lens is filled up by a transparent gelatinous mass called the vitreous humour. The vitreous humour consists of 99 percent water and is contained in a thin hyaloid membrane.

Pig eyes are similar to human eyes in anatomy, vasculature and photoreceptor distribution. However, pigs have dichromatic vision, where only two pigment cones create colors, compared to the human trichromatic vision. This results in a less color rich world compared to human, although they can still differentiate colors.