Uveitis
Definition
Uveitis refers to inflammation of the middle layer of the eye, known as the uvea. The uvea is composed of three components: the iris (the colored part of the eye), the ciliary body (which makes the fluid that naturally fills the eye), and the choroid (a vascular layer underlying the retina). Uveitis is responsible for about 10% of the cases of blindness in the United States.
Uveitis is typically categorized into three anatomic types – anterior, intermediate, and posterior:
- Anterior Uveitis: Anterior uveitis refers to inflammation that affects the front of the eye and is sometimes called iritis. Anterior uveitis accounts for the majority of uveitis cases (70-90%).
- Intermediate Uveitis: Intermediate uveitis refers to inflammation just behind the iris, sometimes known as pars planitis.
- Posterior Uveitis: Posterior uveitis refers to inflammation of the retina or choroid. If all three categories are involved, the term panuveitis is used.
Causes and Associations
Uveitis can occur at any age and result from many causes. Broadly, these can be grouped as traumatic, immunologic, infectious, and masquerade causes:
- Traumatic
Trauma, from the eye being struck by something, is a common cause of anterior uveitis. In response to the traumatic insult, the eye produces many white blood cells which comprise the inflammation seen by the ophthalmologist. If the trauma is severe, bleeding can accompany the uveitis and is called a hyphema. - Immunologic
Another common cause of anterior uveitis is immunologic. The inflammation can be associated with autoimmune conditions such as rheumatoid arthritis, ankylosing spondylitis, psoriasis, inflammatory bowel disease or Bechets' disease. HLA-B27 is an immunologic marker that can be associated with immunologic conditions and uveitis. In about half of cases, no cause for anterior uveitis is found. Multiple sclerosis is associated with intermediate uveitis. Sarcoidosis can cause uveitis in any or all parts of the uvea. - Infectious
Infectious causes of uveitis include Lyme disease, syphilis, herpes, tuberculosis, and parasites. Inflammation produced in the eye is designed to combat these infectious causes. If an infection is the cause, it is important to identify and start treating the source of the infection promptly. - Masquerade
Other causes of uveitis can be referred to as masquerade causes. These include lymphoma, intraocular foreign body, leukemia, retinal detachment, or post-operative uveitis (perhaps from an artificial lens rubbing on the iris or ciliary body).When no cause for uveitis can be found, the term idiopathic is used to describe the uveitis.
The most common causes of uveitis by category are listed below:
- Anterior Uveitis: idiopathic, HLA-B27-associated, juvenile rheumatoid arthritis, herpetic, sarcoidosis, lupus, post-operative.
- Intermediate Uveitis: idiopathic, sarcoidosis, multiple sclerosis, Lyme disease.
- Posterior Uveitis: toxoplasmosis, idiopathic, cytomegalovirus, lupus, sarcoid, a group of inflammatory conditions known as the "white-dot syndromes," Vogt-Koyanagi-Harada syndrome, sympathetic ophthalmia.
Symptoms
Symptoms may have sudden or gradual onset; common symptoms of uveitis are:
- eye redness
- blurry vision
- light sensitivity
- floaters
- eye pain or soreness
Examination & Testing
It is important to identify the underlying cause of the uveitis, if possible, because some of the systemic causes are treatable. This is particularly important if the uveitis is severe, affects both eyes, or is recurrent.
The doctor will first obtain a history and ask a review of systems to elucidate anything suspicious for a systemic disease, for example:
- "Do you have any joint or back pain?"
- "Do you have Crohn's disease or ulcerative colitis?"
- "Have you had any tick bites or rashes?"
The doctor will perform a complete eye examination. A laboratory workup might include:
- A complete blood count (CBC)
- RPR or FTA-ABS (for syphilis)
- A chest x-ray (for sarcoid)
- A PPD (for tuberculosis)
- HLA-B27
What the Doctor Sees
When a doctor examines the patient, he or she will use a slit lamp that projects a bright light on and into the eye. Careful examination of the eye can reveal the white blood cells that comprise the inflammation floating in the anterior part of the eye in front of the iris, or more posteriorly, behind the iris. Examination of the retina can reveal any white spots or lesions that might suggest a cause.
Prognosis
It is very important to treat a case of uveitis promptly and effectively because ongoing inflammation in the eye can cause permanent eye damage. Chronic uveitis can cause the iris to stick onto the lens permanently and severely reduce vision.
Depending on the cause, location, and severity of uveitis, an episode can be brief or more long-lasting. A patient may have only one episode of anterior uveitis in his or her life, or a patient could battle recurrent uveitis for their entire life. Each case is different.
Other long-term complications of uveitis include: cataracts, glaucoma, band keratopathy (opaque calcium deposits on the cornea), and retinal edema.
Prevention
Aside from avoiding trauma and treating any identifiable systemic diseases, there is nothing that can be done to avoid uveitis. Diet and exercise do not contribute to uveitis. A prompt eye exam if any of the above symptoms occur is the best way to detect uveitis early and start treatment.
Treatment
The mainstay of treating uveitis is steroids. Steroids decrease inflammation. Most commonly these steroids can be administered in the form of eye drops. An ophthalmologist may direct the eye drops be used anywhere from four times a day to every hour. If drops do not adequately quell the inflammation, steroids can be administered orally or via injection around the eye or even inside the eye. For very severe cases, chemotherapeutic agents such as methotrexate can be used to control the immune system, often with the assistance of a rheumatologist.
In addition to steroids, ophthalmologists may prescribe a dilating eye drop to decrease the discomfort that occurs when the iris is inflamed and to mitigate the chance that the iris will become scarred and stuck onto the lens. While being treated with steroids, the ophthalmologist will want to regularly check the eye pressure, which can be elevated when using steroids.
For a typical case of uveitis, the ophthalmologist will use steroid drops and follow the patient to see if the inflammation decreases. If it does, then the ophthalmologist will slowly taper the steroid drops because abruptly stopping all drops can lead to flaring of the uveitis. This gradual tapering of steroid drops can take weeks to months.
Any identifiable systemic cause of the uveitis must be treated promptly.
Uveitis
Author: Allen C. Ho, M.D.
