The stroma of iris is the middle layer of tissue in the iris of the eye. Synonyms for this term include the iris stroma or simply iris tissue. Additionally, the stroma of iris contains pigmented cells that give the iris its color and control the amount of light that enters the eye. This layer is also responsible for separating the anterior and posterior chambers of the eye. The iris stroma is composed of fibroblasts, melanocytes, and collagen fibers. Its function is essential for the regulation of the amount of light entering the eye, and any damage to it can result in abnormalities such as iris cysts or inflammation.