The iris acts as a dynamic diaphragm. It can dilate and contract altering the amount of light which is allowed to pass through the pupil and into the eye. In the dark of night, the iris will become fully dilated, capturing every possible photon. However, shine a bright light in a person's eye and the iris will shrink down almost instantaneously to prevent that excess light from damaging the retina.
The iris is actually just a one part of the three-part uvea. The uvea is made up of the Iris, the Ciliary Body and the Choroid.
In this module, we review the anatomy and cellular structure of the anterior Uvea. We then move on to iris pathology - identifying several key infectious and autoimmune conditions which can result in iris inflammation.
Next we visit the posterior uvea (simply the choroid) and identify things that can go wrong with this component of the eye.
Finally, we review the general pathologies which can affect all components of the uvea in a condition called Uveitis.
Issue Date: 08/01/2020