The Iris is the blue, brown, green,gray, or what-have-you colored diaphragm of the eye.It contracts and dilates, making the pupil small or large and thus regulates the amount of light admitted into the eye.
The iris contracts and dilates by the action of minute muscles.Circularly arranged muscle fibers contracts it and horizontally arranged fibers dilate it.
The circular muscle is controlled by the third cranial nerve (motor oculi) and the dilating muscle is controlled by the sympathetic nervous system.
The color of the iris really makes no difference and the brown is as good as the blue as far as the healthy eye is concerned. But sometimes one iris may have a different color from its next-door neighbor, and this may indicate is a diseased condition unless one was born that way, which happens once in a while.
The color of the iris is produced by pigmented cells.
Iritis is an inflammation of the iris which may be caused by systemic diseases, such as diabetes and rheumatism, or infections like tuberculosis, syphilis and gonorrhea.
It is often produced by injuries or by disease of other parts of the eye. Never allow your eyes to be treated by druggists or opticians, see an eye doctor. Meanwhile bathe it with boric acid solution (a teaspoonful to a glass of water ) and keep the eye covered with sterile gauze held by adhesive plaster