What is the purpose of the Iris in the eye (appart from make us look beautiful :D)?

In addition to controlling the amount of light entering the eye through the pupil, the iris serves a further function.


For spherical refracting surfaces (or lenses, like the one in your eye), rays that are further from the optical centre are refracted (bent) more than those closer to the centre. The result is that when the image is formed on the retina, it may be slightly out of focus.





The iris reduces the number of these rays by forming a barrier over the parts of the lens in the eye which might cause this, and thus producing a more sharply focussed image on the retina.What is the purpose of the Iris in the eye (appart from make us look beautiful :D)?
The iris is actually the muscle that expands and contracts to control the size of the pupil.





Without it you wouldn't be able to see in focus.What is the purpose of the Iris in the eye (appart from make us look beautiful :D)?
they contract or expand inorder to get more or less light.
It changes in size to adjust the amount of light striking the retina.( Pupil dilation)
Iris is a structure made of thin elastic tissue with an opening in the center which is surrounded by a circular muscle called a sphincter. This structure is called the iris and the opening 鈥?the pupil. It is the iris that determines the color of the eye 鈥?blue, brown, etc. The backside of this tissue is made up of cells containing brown pigment which acts to absorb light as well as prevent its scattering within the eye. The front layer of tissue varies in thickness; the thicker it is, the bluer the eyes appear to be when seen through the clear cornea. The purpose of the iris is to control the amount of light entering the eye and thereby prevent dazzle by bright lights. As the pupil gets smaller in bright light, the acuity of vision typically increases through a process called defraction and by the fact that less of the peripheral cornea is involved limiting the amount of spherical aberration. Camera buffs should get the idea immediately.
It is the part of the eye that expands and contracts so that the proper amount of lighting can get in. It protects the pupil so that it does receive too much or too little light.
I think the Iris or pigment of the eye helps protect it from harsh lighting.

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