iris of the eye (orris, I)

Structure

• the anterior division of the vascular covering of the eye
• in its center in the pupil; at its periphery is the sclera
• it is composed of stroma & a double layer of pigmented retinal epithelium from which are derived the sphincter pupillae & dilator pupillae muscles of the pupil
• the iris collarette is a landmark that separates the central pupillary zone from the peripheral ciliary zone
  • it is typically flat but can be prominent, a normal variant that requires no treatment (image)

More general terms

• eye structure

Additional terms

• immune reconstitution inflammatory syndrome (IRIS)