By: Kristin Jaskowiak
The organ that gives us a sense of sight is our eyes. Of the five senses, our eyes allow us to learn the most about our surroundings. It is important to know the structures and anatomy that make up the eyes to gain a better understanding of how light and images are processed to become sight. ANATOMY
The lacrimal gland, or tear duct, produces tears when stimulated by the facial nerve. The delicate, transparent mucous membrane that covers the inside of the eyelids and the anterior surface of the eye is the conjunctiva. The sclera is the white, tough, fibrous connective tissue that makes up the whites of the eyes. The cornea is the window of the eye and helps to focus entering light rays. The iris is the colored portion of the eye. The muscles of the iris involuntarily increase or decrease the diameter of the pupil. The pupil is the dark, round central opening that allows light rays to enter the internal eye. The lens is the clear, flexible disk behind the pupil. The layer of tissue that lines the posterior cavity of the eye is called the retina. Rods and cones are located in the retina. Rods are light sensitive cells that detect black and white and function in daytime and nighttime vision. Cones are light sensitive cells that detect color and respond to red, green, or blue light. The vitreous humor is the clear, gel-like substance that fills the posterior cavity of the eye. PROCESS OF VISION
The process involves light waves that enter the eye through the cornea, then the crystalline lens, and then the vitreous humor till the reflected light waves can project onto the photoreceptors of the retina. Due to the refraction of light on the cornea and lens, the image projected on the retina is inverted and reversed from left to right. The impulses from the retina converge to the optic nerve then to the brain where they are transferred into imagery. Continual adjustments of the lens and pupil regulate the entry and...