Stroma of iris

Some circle the circumference of the iris and the majority radiate toward the pupil.

Blood vessels and nerves intersperse this mesh.

In dark eyes, the stroma often contains pigment granules.

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 commonly, heavily pigmented epithelial layer that is two cells thick (the iris pigment epithelium), but the front surface has no epithelium.

Structure of the iris and surrounding parts showing the stroma of iris ( stroma iridis ).
1:posterior segment 2:ora serrata 3:ciliary muscle 4:ciliary zonules 5:Schlemm's canal 6:pupil 7:anterior chamber 8:cornea 9:iris 10:lens cortex 11:lens nucleus 12:ciliary process 13:conjunctiva 14:inferior oblique muscule 15:inferior rectus muscule 16:medial rectus muscle 17:retinal arteries and veins 18:optic disc 19:dura mater 20:central retinal artery 21:central retinal vein 22:optic nerve 23:vorticose vein 24:bulbar sheath 25:macula 26:fovea 27:sclera 28:choroid 29:superior rectus muscle 30:retina 1: posterior segment 2: ora serrata 3: ciliary muscle 4: ciliary zonules 5: Schlemm's canal 6: pupil 7: anterior chamber 8: cornea 9: iris 10: lens cortex 11: lens nucleus 12: ciliary process 13: conjunctiva 14: inferior oblique muscule 15: inferior rectus muscule 16: medial rectus muscle 17: retinal arteries and veins 18: optic disc 19: dura mater 20: central retinal artery 21: central retinal vein 22: optic nerve 23: vorticose vein 24: bulbar sheath 25: macula 26: fovea 27: sclera 28: choroid 29: superior rectus muscle 30: retina
1:posterior segment 2:ora serrata 3:ciliary muscle 4:ciliary zonules 5:Schlemm's canal 6:pupil 7:anterior chamber 8:cornea 9:iris 10:lens cortex 11:lens nucleus 12:ciliary process 13:conjunctiva 14:inferior oblique muscule 15:inferior rectus muscule 16:medial rectus muscle 17:retinal arteries and veins 18:optic disc 19:dura mater 20:central retinal artery 21:central retinal vein 22:optic nerve 23:vorticose vein 24:bulbar sheath 25:macula 26:fovea 27:sclera 28:choroid 29:superior rectus muscle 30:retina