What is the Uvea?
The uvea is a highly vascular layer that lines the sclera, and its primary function is to provide nutrition to the eye. The uvea is located beneath the white part of the eye (the sclera). It is composed of the iris, ciliary body, and choroid. These structures control many eye functions, including adjusting to light and to different distances of objects. Uveitis is inflammation of one or more of these structures.
Key Takeaways
The uvea is highly vascular and provides nutrients to the eye.
The uvea is made of the iris, ciliary body, and choroid.
Uveitis is inflammation of the uvea which may indicate systemic disease.
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Understanding the Uvea
The uvea is made of 3 parts: iris, ciliary body, and choroid.
Iris
The iris is the circular, thin diaphragm that separates the eye into anterior and posterior chambers. The iris sits behind the cornea and in front of the lens. The iris regulates the amount of light that enters the eye.
Ciliary Body
The ciliary body produces aqueous which bathes the structures of the anterior segment, which is the front part of the eye. The ciliary muscle is part of the ciliary body. The ciliary muscle aids in accommodation which is the ability of the eye to focus on near objects. The ciliary muscle acts on the zonule fibers which hold the lens in place. The ciliary muscle loses functionality with age resulting in presbyopia (difficult seeing up close).
Choroid
The choroid is the largest part of the uvea. The choroid supplies the outer retina with nutrients, and maintains both the temperature and volume of the eye. The choroidal circulation accounts for 85% of the total blood flow in the eye.
Conditions Affecting the Uvea
Uveitis is inflammation of the uvea and is named by location. Anterior uveitis is the most common type and affects the iris. Intermediate uveitis affects the ciliary body and the vitreous. Posterior uveitis affects the retina and choroid. Panuveitis affects all the parts of uvea. Uveitis can be acute or chronic, unilateral, or bilateral.
Risk Factors for Uvea Inflammation
Uveitis can be idiopathic (of unknown cause) or may be caused by autoimmune or infectious conditions. Cancers like lymphoma may result in intraocular inflammation. Autoimmune conditions that may cause uveitis include AIDS, Ankylosing spondylitis, Behcet’s disease, Lupus, Multiple sclerosis, Psoriasis, Rheumatoid arthritis, Sarcoidosis, Ulcerative colitis, and Vogt-Koyanagi-Harada (VKH) disease. Cytomegalovirus (CMV) retinitis, Histoplasmosis, Reactive arthritis, Shingles, Syphilis, and Toxoplasmosis are infectious systemic causes of inflammation.
Symptoms of Uvea Inflammation
Symptoms of uveitis begin suddenly and may include:
- Pain
- Photophobia
- Redness
- Watery eyes
- Blurry vision
- Floaters
- Reduced vision
- Flashes of light
Diagnosing Inflammation of the Uvea
A doctor makes a uveitis diagnosis by viewing the front of the eye through a slit-lamp. Lid edema, red eye, swelling, keratic precipitates, aqueous flare, and changes in the iris are commonly signs of uveitis in the front of the eye. A doctor will also dilate the eye to look for inflammation in the back of the eye. Snowball-like exudates, macular edema, nerve swelling, and vitreous and retinal hemorrhages may be viewed in the back of the eye. Uveitis can also result in an increase in intraocular pressure.
Treatment for Uveal Inflammation
Uveitis is treated with steroids to reduce the inflammation in the eye. Topical steroid eye drops are the most common treatment. Some patients may require oral steroids to control systemic inflammation. In more advanced cases, steroids may be intraocularly injected.
