How The Eye Works


  • Light rays enter the eye through the clear cornea, pupil and lens.
  • These light rays are focused onto the retina, the light sensitive tissue lining the back of the eye.
  • The retina converts light rays into impulses; sent through the optic nerve to the brain, where they are recognized as images.
  • Seventy per cent of the eye’s focusing power comes from the cornea and the remainder comes mainly from the lens.

Eyes are the organs of vision. Through a complex process, they detect and focus light to create images. Vision begins when light rays are reflected off of an object and enters the eye through the cornea and then pupil. It then passes through the crystalline lens which refracts light to be focused on the retina. By changing shape, the lens functions to change the focal distance of the eye so it can focus on objects at various distances. When light hits the retina, tiny cells, rods, and cones, capture the light signals and convert them into electrochemical impulses in neurons. Rods communicate the object’s shape by reading black and white and shades of gray. Cones communicate the color of the object. Working together, the rods and cones process the light to create an image by triggering nerve impulses that pass to the image centers in the brain via the optic nerve.

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