Messages are picked up by sensory neurons in the peripheral nervous system and passed to interneurons in the central nervous system; responses are passed on to motor neurons in the peripheral nervous system

The fovea centralis, also known as the focal point, is the point where an image is centered when you stare at objects. This region of the retina has a high number of cone and rod cells, and explains why we can only clearly focus on one object at a time. Only the object lined up with the fovea centralis will remain clear, while peripheral objects appear blurry.

The cornea is avascular and made primarily of collagen, not lipids. When light first reflects off of a focused object, it strikes the eye on the cornea, where its high refractive index (1.4) allows most of the bending of light to occur at the interface between air and cornea. Unlike the lens, the cornea does not change its shape. The lens is tethered by suspensory ligaments, which are further connected to ciliary muscles. When the ciliary muscles contract, they release tension on the suspensory ligaments, thus making the lens more spherical and bringing the focal point closer to the lens. 

Rods and cones are two photoreceptors located on the back of the retina that are responsible for black, white (dark and light), and color sense. Rods are responsible for light and dark and are extremely sensitive, while cones sense color and are less sensitive.

The pupil and retina are both anatomical structures of the eye. The pupil controls the amount of light to pass through the eye, and the retina converts the electromagnetic signal to a neural stimulus.

The optic nerve collects stimuli from the retina and exits through the back of the eye to relay the information to the occipital lobe of the cerebrum. The point at which the optic nerve exits the eye contains no photoreceptors (rods and cones), and is unable to interpret light signals. This leads to a blind spot in the eye at the optic disk.

Rods and cones are the primary photoreceptors in our eyes. The rods are responsible for night vision, allowing us to differentiate different grays and blacks, whereas the cones are responsible for sensing color. Rods are concentrated in the periphery of the retina, making them essential for peripheral vision as well.

The retina contains both rods and cones and is responsible for converting electromagnetic stimulation to electrical impulses. These impulses are fired through the optic nerve to the occipital lobe for processing. The lens helps to focus light on the retina.

Rods and cones are the primary photoreceptors in our eyes. The rods are responsible for night vision, allowing us to differentiate different grays and blacks, whereas the cones are responsible for sensing color. There are three main pigments in cones, each perceiving one type of color: red, green, or blue. Deficiency in one type of cone can result in color blindness.

The retina contains both rods and cones and is responsible for converting electromagnetic stimulation to electrical impulses. These impulses are fired through the optic nerve to the occipital lobe for processing. The lens helps to focus light on the retina.

The two major photoreceptors of the body are cone cells and rod cells. Cone cells are most highly concentrated in the fovea and are best for color vision and visual acuity. In contrast, rod cells are found in higher concentrations away from the fovea (at the periphery of the retina) and used for seeing low levels of light and peripheral vision. Rod cells are therefore the photoreceptors used for night vision.

Ganglion cells and bipolar cells are also cells of the retina. They are used in the transmission of the electrical signals from the photoreceptors to the optic nerve and brain.

The pigmented part of the eye, called the iris, regulates the amount of light entering the eye. The iris is actually a band of circular muscle capable of regulating the size of the pupil. By dilating or constricting, this ring controls the amount of light that can enter the eye.

The ciliary muscles are responsible for altering the lens shape. When these muscles contract, the lens flattens and the focal length is reduced, allowing focus on objects closer to the eye. While the lens plays an important role in focusing light, it cannot be stimulated directly and relies on action of the ciliary muscles to change its shape.

The optic nerves cross over in a location known as the optic chiasm, located posterior to the eyes in the brain. The optic tract refers to the portion of the optic nerve that carries signals prior to the optic chiasm, and thus is not involved in the cross. The result of the optic chiasm is that information from the right eye is transmitted to the left visual cortex, while information from the left eye is transmitted to the right visual cortex.

The blind spot created by the optic nerve exiting the eye is known as the optic disc.