The process of transforming light energy into neural impulses that can then be interpreted by the brain.

The human eye is sensitive to only a limited range of radiation, consisting of wavelengths between approximately 400 to 750 nanometers (billionths of a meter).

The full spectrum of visible color is contained within this range, with violet at the low end and red at the high end. Light is converted into neural impulses by the eye, whose spherical shape is maintained by its outermost layer, the sclera. When a beam of light is reflected off an object, it first enters the eye through the cornea, a rounded transparent portion of the sclera that covers the pigmented iris. The iris constricts to control the amount of light entering the pupil, a round opening at the front of the eye. A short distance beyond the pupil, the light passes through the lens, a transparent oval structure whose curved...