When seen enlarged by macro photography, the human eye is an amazing landscape.
According to Wikipedia, "The iris consists of two layers: the front pigmented fibrovascular tissue known as a stroma and, beneath the stroma, pigmented epithelial cells. The stroma connects to a sphincter muscle (sphincter pupillae), which contracts the pupil in a circular motion, and a set of dilator muscles (dilator pupillae) which pull the iris radially to enlarge the pupil, pulling it in folds."
The features on the front of the iris include:
- The Crypts of Fuchs are a series of openings located on either side of the collarette that allow the stroma and deeper iris tissues to be bathed in aqueous humor. Collagen trabeculae that surround the border of the crypts can be seen in blue irides.
- The pupillary ruffs (crenations) are a series of small ridges at the pupillary margin formed by the continuation of the pigmented epithelium from the posterior surface.
- The Circular contraction folds, also known as contraction furrows, are a series of circular bands or folds about midway between the collarette and the origin of the iris. These folds result from changes in the surface of the iris as it dilates.
- Crypts at the base of the iris are additional openings that can be observed close to the outermost part of the ciliary portion of the iris.
Wikipedia on the Iris
Photos by Suren Manvelyen.