The vascular tunic is the middle layer of the eye. The iris is a circular diaphragm anterior to the lens. It has a central aperture called the pupil , a peripheral border called the ciliary border, and a central border called the pupillary border. The iris separates the anterior segment of he eye into the anterior and posterior chambers. The iris stroma consists of loose, pigmented, highly vascularized connective tissue with pigment epithelium lining the posterior surface.
Eye color is determined by the relative member of melanocytes in the stroma.
It is a single layer of simple columnar epithelium containing melanin. Apical processes interdigitate with the outer segments of photoreceptors. The neural retina is composed of nine layers. These cells are located at the outer segments of photoreceptor cells. These are dense junctional complexes.