Women are easier as they can resort to the help of cosmetics. With shadows, colored pencils and mascara can significantly shade eye color. Blue Iris will look almost transparent, if the eye contour cut around the black pencil or eyeliner. Brown and green eyes will become more vivid if you use a contrasting shade - gray or blue.
To my eyes looked black in the Middle Ages beauties dripping in them tincture of belladonna. Thanks to its constituent atropine, pupils significantly increased. Iris becomes almost invisible. But this remedy has many side effects. Therefore, this method is undesirable.
There are modern drop from glaucoma, which also affect the change eye color. But they have many side effects, so the use of healthy people they can not.
Even eye color can change throughout life. For example, many children are born with gray eyes, but with age they acquire different shades of the iris and a blue, green or brown. With age the eyes are usually also change their color. Iris fades, it becomes lighter. Even dark brown eyes with age may become honey colored.
To change the eye color can affect stress or serious illness. Some eyes change hue depending on the weather or mood. Generally these changes are minor. Blue iris can buy green or gray. Brown eyes are practically unchanged.