The function of the iris is to control light levels in the eye. The round, black dot in the center of the iris is called the pupil.Know More
The iris is the barrier between the front and back of the eye. Each iris has a muscle running through it that constricts and dilates to allow the right amount of light to enter the eye at any given time. The sphincter muscle lies around the edge of the pupil. In bright light, this muscle contracts, allowing only a small amount of light to get it. In dim light, the sphincter muscle dilates, letting in as much light as possible.
Each person's texture, color and pattern of the iris is unique and the color of the irises come from a pigment called melanin. Eye color comes from the amount of melanin a person produces in black/brown or red/yellow combinations.
Like other parts of the body, the iris may become diseased or infected. When the iris becomes inflamed, the result may be blurred vision and light sensitivity. Iridocyclitis is a condition in which the iris requires antibiotics to function normally. Congenital problems of the iris such as, iris coloboma and aniridia are rare and require seeking professional medical treatment.Learn More
The iris of the human eye is the pigmented portion of the eye. It is visible through the outermost layer of the eye, or the cornea. The iris is comprised of connective tissue and smooth muscle fibers.Full Answer >
According to the American Optometric Association, the eye works by light entering the eye and traveling through the different parts of the eye. Each part plays a vital role in creating a visual image.Full Answer >
Although the curvature of the Earth's surface causes objects to be out of sight within 3.1 miles, the farthest object visible to the naked eye is the Andromeda galaxy, located 2.6 million light-years away from Earth. The amount of photons a distant object emits determines whether it can be seen.Full Answer >
Black eyes are caused by bleeding underneath the skin due to blunt impact. The skin underneath the eyes is thinner, so blood pooling in the area is more obvious than in other areas, giving the distinctive shine to a black eye.Full Answer >