The term 'PART OF THE EYE CONTAINING THE IRIS' can be summarized as the Uvea, which is a four-letter word. The Uvea is the middle layer of the eye, located between the sclera and the retina. It contains the iris, ciliary body, and choroid. The iris is the colored part of the eye that controls the amount of light entering the eye. The ciliary body is responsible for controlling the shape of the lens and the production of aqueous humor. The choroid is a layer of blood vessels that provides oxygen and nourishment to the eye.