<P> 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 back surface is covered by a heavily pigmented epithelial layer that is two cells thick ( the iris pigment epithelium ) , but the front surface has no epithelium . This anterior surface projects as the dilator muscles . The high pigment content blocks light from passing through the iris to the retina , restricting it to the pupil . The outer edge of the iris , known as the root , is attached to the sclera and the anterior ciliary body . The iris and ciliary body together are known as the anterior uvea . Just in front of the root of the iris is the region referred to as the trabecular meshwork , through which the aqueous humour constantly drains out of the eye , with the result that diseases of the iris often have important effects on intraocular pressure and indirectly on vision . The iris along with the anterior ciliary body provide a secondary pathway for aqueous humour to drain from the eye . </P>
<P> 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 back surface is covered by a heavily pigmented epithelial layer that is two cells thick ( the iris pigment epithelium ) , but the front surface has no epithelium . This anterior surface projects as the dilator muscles . The high pigment content blocks light from passing through the iris to the retina , restricting it to the pupil . The outer edge of the iris , known as the root , is attached to the sclera and the anterior ciliary body . The iris and ciliary body together are known as the anterior uvea . Just in front of the root of the iris is the region referred to as the trabecular meshwork , through which the aqueous humour constantly drains out of the eye , with the result that diseases of the iris often have important effects on intraocular pressure and indirectly on vision . The iris along with the anterior ciliary body provide a secondary pathway for aqueous humour to drain from the eye . </P>
muscular tissue present in the iris of the eye
muscular tissue present in the iris of the eye
sphincter muscle ( sphincter pupillae ) dilator muscles ( dilator pupillae )
sphincter muscle ( sphincter pupillae ) dilator muscles ( dilator pupillae )