What does the Iris in the human eye do?

Answer 1

The iris is a membrane in the eye, responsible for controlling the diameter and size of the pupil and the amount of light reaching the retina. "Eye color" is the color of the iris, which can be green, blue, or brown. (Wikipedia)

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Answer 2

The iris has the job to control the amount of light reaching the retina. It also (as a side affect) controls the depth of field - which is why it is easier to read small print in a good light. It is the colored contractile membrane of the eye. It separates the anterior and posterior chambers of the eyeball and is perforated in the center by the pupil. The iris, by contraction and dilatation, regulates the entrance of light into the eye. It regulates the amount of light that passes onto the retina of the eye, by reducing its aperture area in a bright light. The term is also used for the device in a camera which alters the amount of light which is admitted. This is also called an adjustable diaphragm.

The pupil is the black part of your eye. Actually it is not black, but transparent, but appears as black because most light is absorbed by the tissues inside your eye. The pupil is responsible for controlling the amount of light reaching your retina, which is where images are formed. This is done by having the iris enlarge or reduce the size of the pupil. An enlarged pupil will allow more light to enter your eye, while a constricted pupil will allow less. Enlarged pupils are common during night time and constricted pupils are common during the day.

Two layers of intrinsic smooth muscle fibers controlled by the autonomic nervous system expand and contract to control the volume of light entering the eye. Pupillary constrictor muscles are a type of sphincter muscle that constrict to restrict light flow. Pupillary dilator muscles are radial smooth muscles which contract to dilate the pupil.

Answer 3

The iris is actually the muscle responsible for helping your eye adjust to changes in light. By contracting and relaxing the spoke-like muscle in it, the iris widens to let in more light in dim places or shrinks the size of the pupil to avoid damage to the retina from U.V. rays. This is an involuntary reaction. Also, the color of the iris is based purely on genetics. It opens and closes the pupil to control amount of light allowed through.

Answer 4

The Iris is simply a muscle muscle with a hole in it (the pupil). It controls how much light enters the eye. At night or in a dark room for example, we need more light to see, so the pupil dilates to allow more light to enter. Another factor plays a role here, when the pupil was constricted (before you entered the dark room) the light was focused on the central retina, where there are almost no rods (rods are sensitive to light, basically we need the to see where there is minimum illumination).Now, the cones in the central retina are not sensitive to light, so when the iris dilates the pupil so the light could get to the rods.

Answer 5

the iris is seen as the coloured bit of the eye. However it had a much greater function than just looking pretty!

The iris is controlled by the pupillary muscles which contract and relax to allow more, or less, light into the eye depending on the brightness of the surroundings

:)

Answer 6

The iris is important because it adjusts the amount of light that enters the eye.

Answer 7

They can have hundreds of combinations of colors- but similar appearance. The link below will take you to an article in iris, and pictures. enjoy-