It may not have the name recognition of the iris or pupil, but the ciliary body is of no less importance to a healthy functioning eye. Your eye is made up of a protective outer layer (cornea and sclera), an inner layer (uvea) that supplies blood and nutrients, and an inner layer (retina) that receives light and sends messages through the optic nerve that tells the brain to transform the light into images. The ciliary body is part of the uvea. Learn what it does, why it’s important, and what its relationship is to glaucoma and other eye diseases.*

What is the ciliary body?

The ciliary body is a ring-shaped tissue hidden behind the iris, or colored part of the eye, that encircles both the iris and lens. Between the lens and retina at the back of the eye is a fluid called aqueous humor, that nourishes the eye and helps maintain its shape.

What does the ciliary body do?

The ciliary body serves two main functions.

• Its muscles contract and relax so we can see near and distant objects (a process called accommodation), and
• Its blood vessels (capillaries) release aqueous humor in the front of the eye to:
  • Keep the eye inflated,
  • Control eye pressure, and
  • Carry nutrients to the lens and cornea.

When the ciliary body produces too much fluid, or when a normal amount of fluid is blocked from draining properly, the pressure inside the eye builds up and damages other parts of the eye, impairing vision. Glaucoma is when increased pressure damages the optic nerve. 

What makes up the ciliary body?

Two important parts of the ciliary body are the ciliary muscle and the ciliary process.

• The inner ciliary body consists of smooth muscles that respond automatically, contracting and relaxing, to objects we see in our environment.
• The ciliary process consists of vessels that secrete aqueous humor, located inside numerous folds for greater surface area and fluid secretion.

What conditions can happen to the ciliary body?

There are several ways that the ciliary body can become damaged. 

• Anterior segment dysgenesis (ASD), a congenital variation in ciliary body anatomy, can impact how the front of the eye develops. 
• Blunt trauma, such as from a deployed airbag or a hard blow to the head, can lead to iris inflammation and eye pressure changes. In severe cases, ciliary muscles can detach from the ciliary body (cyclodialysis). This can cause blood to pool in the eye (hyphema).
• Intraocular melanoma, a rare cancer of the eye’s melanocytes (cells that produce pigment, or color) that can impact the uvea. Symptoms of intraocular melanoma may include blurry vision, seeing spots, dark spots on the iris, and changes in the pupil’s size or shape.
• Older adults and fair-skinned people with blue or green eyes are at higher risk.
• Prognosis depends on:
  • the spread of cancer cells and 
  • where the cancer is in the eye, 
  • tumor size and thickness, and 
  • a person’s cancer history.
• Treatment can include surgery, charged particle external beam, or plaque radiation.

Assessing ciliary body function and damage

Testing for ADS is done through a physical exam and medical history. For other conditions, a doctor may conduct:

• A dilated pupil eye exam 
• A fluorescein angiography in which an injected dye travels through the eye to detect leaks or blockages
• A high-resolution ultrasound biomicroscopy for high-resolution imagery 
• An ultrasound exam for a deeper analysis of the eye structure

Damage to the ciliary body can impact the structure’s ability to function properly, potentially leading to further complications, including glaucoma. If you have any problems with your eyes or vision, speak with your eye doctor sooner rather than later.

*Climan, A. (2022, May 5). The Anatomy of the Ciliary Body. Verywell Health. https://www.verywellhealth.com/ciliary-body-5115271