How does the human eye distinguish colours?

Human eye mainly consists of three parts namely pupil, lens and retina. Anything we see has rays of light bouncing off it; this light enters into the eye through the pupil. The lens present behind the pupil bends the light rays and the clear picture of that object is created on the retina which is present at the back of the eye and is sensitive to light. From retina this picture goes to the brain, the retina of the human eye consists of rod shaped and cone shaped cells, the rod shaped cells respond to the brightness of the light while cone shaped cells respond to the colours. It is with the help of these cone shaped cells that we can see and distinguish colours.

Fascinating ‘eye’ facts

• Human eye can distinguish about 10 million colours.
• The eye is not shaped like a perfect sphere. It is a fused two piece unit, the curved small frontal unit is called cornea and the larger unit is called sclera.
• Opthalmoscope is used to test the eye.
• The eye attains its full size by age 13.
• A typical adult eye has an anterior and posterior diameter of 24 mm, a volume of six cubic centimetres and a mass of 7.5 grams.
• The field of view of human eye is 95 degrees away from the nose, 75 degrees downward, 60 degrees towards the nose, and 60 degrees upwards. It allows the humans to have 180 degree forward facing horizontal field of view.
• The eye has lens similar to the lenses found in optical instruments like cameras.
• When looking intently the eyes drift around.
• Each eye has six muscles to control its movements.
• When the head moves towards the right side, the eyes move to the left and vice versa.