Vision is the most fundamental of human senses.The human eye is a·very complex and truly amazing organ.

    It is approximately one inch wide and deep, and 0.9 inches high. Human eyes allow us to appreciate all the beauty of the world we live in, to read and gain knowledge, and to communicate our thoughts and desires to each other through visual expressions, and arts. The front of the eye includes: iris (the pigmented part), cornea (a clear dome over the iris), pupil (the black circular opening in the iris, which lets light in),sclera (the white part), and conjunctiva (an invisible; clear layer of tissue covering the front of the eye,except the cornea).

    Just behind the iris and pupil lies the lens ,which helps focus light on the back of the eye. Most of the eye is filled with a clear gel called the Vitreous. Light projects through the pupil and the lens to the back of the eye. The inside lining of the eye is covered by special light-sensing cells, together called the retina. The retina converts light into electrical impulses. Behind the eye, the optic nerve carries these impulses to the brain. The macula is a small sensitive area within the retina that gives central vision. It is located in the center of the retina and contains the fovea. Eye color is created by the amount and type of pigment in the iris. Multiple genes inherited from each parent determine a person's eye color.

Adopted from: - http://faculty.atu.edu/cbrucker/Engl2053/Samples/Yang13.htm (April 1, 2020)
                     - http://www.webmd.boots.com/eye-health/guide/picture-of-the-eyes (April 1, 2020)

The white part of the eye is called ....