Identify the heavily pigmented choroid layer surrounding the retina (Fig. 23-23).

• Follow this anteriorly and note the ciliary body (Fig. 23-5).
• Identify smooth muscle in the ciliary body, projecting ciliary processes, and remnants of the zonule or suspensory ligaments.
• At the limbus, near where the ciliary body and iris join the cornea, identify the endothelium-lined spaces of the canal of Schlemm (Fig. 23-6).

List three functions of the ciliary body.

What is the functional relationship between the ciliary processes and the canal of Schlemm?

Why is the zonule seldom seen intact on microscope slides?

Clinical note: Glaucoma results from the decreased outflow of aqueous humor through the trabecular meshwork and the canal of Schlemm. This elevates intraocular pressure, which can damage peripheral areas of the retina and cause progressive loss of vision. Various medications can lower the pressure and laser surgery can be used to improve drainage through the trabecular meshwork. To the right is how person with glaucoma sees the world.

The lens is next.