page_title: Iris (anatomy)
section_title: Microanatomy
hierarchical_section_title: Iris (anatomy) / Structure / Microanatomy
caption_attribution_description: English: The anterior chamber angle of a 57 year old male (cross-section view). Sclear, scleral spur, trabecular meshwork, and iris can be seen.Iris is concave in this patient with a "4+" chamber angle depth. Below, a viewfinder shows which section of the eye has been imaged. This image is released to Wikimedia with patient consent. Imaged in-vivo with an Optovue iVue Spectral Domain Optical Coherence Tomographer (SD-OCT) at the office of Drs. Harry Wiessner, Steven Davis, Daniel Wiessner, and Eric Wiessner in Walla Walla, WA, USA.
context_page_description: In humans and most mammals and birds, the iris is a thin, annular structure in the eye, responsible for controlling the diameter and size of the pupil and thus the amount of light reaching the retina. Eye color is defined by that of the iris. In optical terms, the pupil is the eye's aperture, while the iris is the diaphragm.
context_section_description: From anterior (front) to posterior (back), the layers of the iris are:
  Anterior limiting layer
  Stroma of iris
  Iris sphincter muscle
  Iris dilator muscle (myoepithelium)
  Anterior pigment epithelium
  Posterior pigment epithelium
caption: Anterior chamber cross-section imaged by an SD-OCT.
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