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The process of seeing begins when light waves enter the front of the eye.

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Brightness and distinct colors are first interpreted by structures in the back of the eye,

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and then sent as stimulus signals that the brain interprets as vision.

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On the exterior of the eye is an area called the cornea,

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that includes a pupil, a hole through which light enters the eye.

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Inside the eye, light is refracted by a lens

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and focused onto the retina, a layer of receptors that lines the inside of the eye.

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The retina includes two types of nervous system cells:

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cones that interpret color of light waves,

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and rods that interpret the intensity of light.

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These photoreceptors process information into nerve signals that travel through the optic nerve

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into the occipital lobe of the brain, where signals are interpreted to represent an image.