The ciliary body is one of the important organs in the eye and is involved in adjusting the focus of the lens and secreting aqueous humor.

The ciliary body is located just behind the iris and surrounds the lens.
The ciliary body consists of a muscle called the ciliary muscle and a fine structure called the ciliary processes.

The ciliary body has two main functions:

1. Focus adjustment
The thickness of the crystalline lens changes as the ciliary muscles contract and relax.
This allows the eye to adjust the focus when looking at near or far objects.

• ・When looking at something close → the ciliary muscle contracts → the lens becomes thicker.
• ・When looking at something far away → the ciliary muscle relaxes → the lens becomes thinner.

When this function declines with age, the condition becomes “presbyopia.

2．Aqueous humor production
Aqueous humor is produced by the ciliary processes, which are part of the ciliary body.

Aqueous humor flows into the anterior chamber (between the cornea and the iris) and exits through an exit called Schlemm’s canal.
Aqueous humor plays an important role in maintaining constant intraocular pressure and providing nutrients to the cornea and lens.
Any abnormality in the production or drainage of aqueous humor can lead to glaucoma.