Uvea

What is the uvea?

The uvea is the middle of three layers that make up your eyes’ outer walls. The term “uvea” comes from words in Latin and Ancient Greek that mean “grape.” That’s because, from the outside, most of the uvea looks like the outside of a grape.

Another name for the uvea is the “vascular tunic.” A tunic is a type of shirt, and “vascular” means “circulation-related.” The uvea wraps around most — but not all — of your eye like a shirt does, and parts of it are packed with blood vessels to provide circulation.

Three distinct parts make up the uvea. These are the:

• Iris.
• Ciliary body.
• Choroid.

What is the purpose of the uvea?

The different parts of the uvea each have their own jobs.

Iris

This is a ring of muscle tissue at the front of your eye, just behind the cornea. It can automatically widen or narrow to control how much light enters your eyes. The iris is also the tissue that gives you your eye color.

Ciliary body

This is a ring of tissue just behind the iris. Muscles in it control the shape of the lens of your eye, helping you focus your gaze on objects around you. The ciliary body also makes aqueous humor fluid, a liquid that fills part of your eye and helps your eye hold its globe-like shape.

Choroid

This is a thin sheet of tissue packed with blood vessels. It’s the largest part of the uvea, wrapping around the central and rear-most sections of your eyeball. It’s just outside the retina (the inner, light-sensitive tissue layer lining the inside of your eye) and just inside the sclera (the white outer eye layer).

If you think about your eye like a house, then the choroid is like that house’s plumbing. The arteries that supply blood to your eye are like the city water supply leading up to the house. Water from the main pipes enters the house and then branches out to different places like sinks, showers and more. That’s similar to how the choroid supplies blood to various parts of your eye (especially your retinas).

Another important feature of the choroid is its color. The choroid contains a lot of melanin, the pigment that gives your skin and eyes their color. Researchers suspect that the choroid helps with absorbing some of the light that enters your eyes, reducing how much light reflects off the retina inside your eye.

What conditions and disorders affect the uvea?

The uvea is vulnerable to several different types of medical conditions. The types of conditions can vary partly because the uvea has multiple parts, each with a different job and makeup.

Conditions that can affect the uvea include (but aren’t limited to) the following:

• Albinism.
• Choroideremia.
• Coloboma.
• Diabetes-related retinopathy.
• Eye cancers (especially intraocular melanoma).
• Eye ischemia (lack of blood flow) like from an eye stroke.
• Injuries.
• Iris malformations like corectopia (misaligned iris) or polycoria (multiple pupils).
• Macular degeneration, especially the wet form.
• Presbyopia (age-related loss of ability to focus on up-close objects).
• Sarcoidosis.
• Synechiae.
• Uveitis.

What are some common symptoms of uvea-related conditions?

Symptoms from conditions can vary depending on which part of the uvea they affect. The symptoms can include (but aren’t limited to) the following:

• Blurred vision.
• Dilated pupils (mydriasis).
• Double vision (diplopia).
• Eye pain.
• Eye strain.
• Headache.
• Light sensitivity (photophobia).
• Swollen conjunctiva.
• Pinpoint pupils (eye miosis).
• Vision loss (either sudden or gradual).
• Pupil shape changes (from a circle to an irregular shape).
• Red eye or eye irritation.
• Watery or teary eyes (epiphora).
• White liquid accumulating at the bottom of the front of your eye (hypopyon) or in a ring around your iris.

How can I protect my uvea?

There are many things you can do to protect your uveal health and your eye health in general. Some of the best steps you can take include:

• Getting regular eye exams. These are like wellness checks for your eye, and they can detect many eye conditions before you have any symptoms. Everyone — not just people who need glasses or contacts — should get an eye exam every one to two years (or more frequently if you have conditions that need more frequent monitoring).
• Wearing eye protection. Goggles and safety glasses can make a huge difference in preventing eye injuries or, at least, limiting how severe they are. And if you wear glasses, don’t assume they’re enough. When in doubt, wear safety glasses made specifically to handle flying object impacts or other hazards.
• Avoiding nicotine use. Smoking, vaping and smokeless tobacco usage can all affect your circulatory system, especially the delicate — yet critical — blood vessels in the uvea.
• Not ignoring infections. If you have what feels like an eye infection for more than a few days, see a healthcare provider. Infections that last more than a few days can easily spread and turn into bigger issues.

When should I talk to an eye care specialist?

Outside of regular eye exams, you should see an eye care specialist whenever you experience eye symptoms that do the following:

• Last longer than a few days.
• Disrupt your usual activities or routine.
• Involve any kind of vision loss.

Sudden vision loss (like blurring, clouding or other changes) is always a medical emergency. If you experience it, call 911 (or your local emergency services number) immediately.

A note from Cleveland Clinic

The uvea may not get all the glory, but that doesn’t mean it’s any less critical to the way your eye works. This multipart structure is right in the middle — literally and figuratively — of what your eye does. When it works like it should, it’s easy to forget how important it can be. But when something is wrong with your uvea, it can be scary not to know what to expect. Regular eye exams are important for catching eye issues — including ones affecting the uvea — before they can cause symptoms and life disruptions.