There are 5 main parts of the eye: Cornea, iris, lens, retina and the optic nerve. Light enters our eye through the cornea, which is the clear, refractive surface of our eye. It is sensitive to dust and foreign particle and is kept clean by tears (which also causes oxygen exchange and maintains the water content). Irides (the plural of iris) can be thought of as the hole through which the incident light passes. It is, in fact, an adjustable opening which controls the amount of light that enters our eyes (by contracting or expanding) and the pigment content in irides is also responsible for the color of our eyes. The lens (actually a converging lens) focuses the received light onto our retina and helps the formation of an image. The retina is the screen on which images are formed and consists of rods and cones cells. The signal is transmitted from the retina to the brain through the optic nerve.
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