Font Size
A
A
A
...
8
...

Anatomy of the Eye (cont.)

Iris and Pupil

The iris, which is the colored part of the eye, controls the amount of light that enters the eye. The iris is a ring shaped tissue with a central opening, which is called the pupil.

The iris has a ring of muscle fibers around the pupil, which, when they contract, causes the pupil to constrict (become smaller). This occurs in bright light. A second set of muscle fibers radiate outward from the pupil. When these muscles contract, the pupil dilates (becomes larger). This occurs under reduced illumination or in darkness.

Must Read Articles Related to Anatomy of the Eye

Cataracts
Cataracts A cataract clouds the lens of the eye, limiting vision. Historically, cataracts were common among such ancient peoples as the Sumeri, the Egyptians, and the Ind...learn more >>
Corneal Abrasion
Corneal Abrasion A corneal abrasion is a painful scrape or scratch of the surface of the clear part of the eye. This clear tissue of the eye is known as the cornea.learn more >>
Eye Allergies
Eye Allergies Up to 50 million Americans suffer from the miseries of allergies, with allergic reactions involving the eyes being a common complaint. An allergic reaction that...learn more >>


NIH talks about Ebola on WebMD

Read What Your Physician is Reading on Medscape

Orbit Anatomy »

Surgical practice begins with a detailed knowledge of anatomy.

Read More on Medscape Reference »


Medical Dictionary