What is uveitis?
Uveitis is a broad term used to describe an inflammation of the uveal tract of the eye.
The uveal tract is composed of:
- The iris: the part of the eye making up a person’s eye color
- The ciliary body: a small muscle behind the iris
- The choroid: a layer of tissue between the retina (a light sensitive inner coat of the eye), and the sclera (the dense connective tissue that forms the white of the eye)
The uveal tract is an area containing a large proportion of the eyes’ blood vessels.
Uveitis typically causes pain and blurred vision, but can, in the majority of cases, be successfully treated through the use of medication. However, if left untreated, the condition can lead to complications including glaucoma, cataracts and possible blindness.
Uveitis is a relatively rare condition, affecting roughly 2-5 people in every 10,000. It can affect people of any age, though is most common in those aged 20 to 59.
Types of uveitis
There are various types of uveitis, each classified according to the part of the uveal tract the inflammation affects:
- Anterior uveitis: Affecting the front section of the uveal tract. This is the most common form of the condition and is typically caused by infection, inflammatory diseases or trauma, e.g. blunt force to the eye.
- Intermediate uveitis: Affecting the middle section of the uveal tract. Typically caused by diseases such as sarcoidosis.
- Posterior uveitis: Affecting the rear of the uveal tract. This is a rare form of the condition.
- Panuveitis: When the condition affects the entirety of the uveal tract. This is the most severe form of the condition, which can lead to serious damage to the retina.
Each type of uveitis is also classified by the frequency at which it occurs. Uveitis can be:
- Acute: Quick to develop and will improve within three months.
- Recurrent: Repeated episodes separated by a number of months.
- Chronic: Episodes last for a significant period and inflammation returns within three months of treatment.
Symptoms of uveitis
Symptoms of uveitis, which may affect one or both eyes, can include:
- Blurred vision
- Floaters (dark, hovering spots in vision)
- Pain in the eyes
- Redness of the eyes
- Light sensitivity (photophobia)
If any symptoms are being experienced or uveitis is suspected, medical attention from a doctor, optician or ophthalmologist (eye specialist) should be sought with urgency.
Signs and symptoms of uveitis differ depending on what type of the condition is being experienced:
- Anterior uveitis is typically associated with pain, blurred vision, light sensitivity and redness.
- Intermediate uveitis is typically associated with floaters and blurred vision, while pain and also eye redness are uncommon.
- Posterior uveitis is typically associated with blurred vision and in some cases a loss of vision, pain is most likely absent and the eye most likely won’t be reddened.
Causes of uveitis
There are three main causes of uveitis:
- An autoimmune disorder or inflammatory disease
- Physical trauma or injury to the eye, including eye surgery
Often, no specific cause of uveitis can be identified.
Autoimmune disorder or inflammatory disease
Autoimmune disorders, such as rheumatoid arthritis and Behcet's disease have been linked to uveitis. An autoimmune disorder is characterized by the body’s immune system producing antibodies to attack its own tissues, with the result, in the case of uveitis, of causing inflammation. The exact reason as to why the immune systems of some people behave this way is unknown.
It is also believed that individuals with inflammatory diseases such as ankylosing spondylitis, reactive arthritis, sarcoidosis and inflammatory bowel diseases, e.g. ulcerative colitis or Crohn’s disease, are more likely to develop uveitis.
Bacterial, fungal or viral infection can cause uveitis in some cases. Possible infection types include toxoplasmosis, herpes simplex, herpes zoster, cytomegalovirus, gonorrhea, tuberculosis and Lyme disease.
If the eye suffers an injury, this can also lead to uveitis.
The first stage of diagnosing uveitis will normally involve a doctor’s examination. If symptoms of the condition are present and uveitis is suspected, a doctor may then refer the individual to an eye specialist (ophthalmologist) for further examination and confirmation of the diagnosis.
Specialists will typically test the individual’s vision, allowing them to see how the condition may be affecting it and assess any differences between each eye. Both eyes will also be examined using a microscope, usually an instrument called a slit-lamp, enabling the doctor to look for signs of inflammation.
Laboratory tests may also be required to rule out infection and any other condition that may be causing the symptoms.
Treatment for uveitis is aimed at reducing pain and inflammation, repairing any loss of vision and attempting to treat any underlying causes. The chosen treatment route will depend upon the specific type of the condition being experienced and what is causing it.
In most cases, medication will be the primary treatment method, but in some cases surgery may also be required.
Treatment will usually include:
The use of steroid medications (glucocorticoids, hormones based on cholesterol) is common in the treatment of uveitis. Steroids can be administered in different ways, with the chosen method depending on what type of the condition is being experienced.
- Steroid eye-drops: Typically used in the initial treatment of anterior uveitis when it is not caused by an infection. The severity of the condition will decide the prescribed dose and how often the drops should be administered. It is important to continue using the eye drops even after symptoms have disappeared to prevent recurrence.
- Steroid injections: Typically used in cases of intermediate or posterior uveitis or if steroid eye drops have proven unsuccessful. The injection is administered to the outside of the eyeball (periocular). A doctor will administer the injection using local anesthetic to minimize any pain or discomfort as much as possible. Generally, only one injection will be needed when the symptoms are at their worst.
- Steroid tablets: The strongest form of steroid medication, usually administered if other options have not worked. Side-effects can be severe, so steroid tablets will generally only be used if there is a risk of permanent damage to the eyes. It is important to continue using the tablets as prescribed even after symptoms have disappeared to prevent recurrence. The severity of the condition will determine how long an individual’s steroid tablet course will have to last, which could be anywhere between a number of weeks and, in much rarer cases, up to a number of years.
Mydriatic eye drops
Mydriatic eye drops may be prescribed in cases of anterior uveitis, in addition to steroid eye drops. This type of medication relaxes the muscles in the eye and thereby widens the pupil of the eye, helping to relieve pain and reduce the risk of glaucoma. They can, however, lead to a temporary blurring of vision.
If uveitis is being caused by an infection, this may be treated using either antibiotics, antiviral medication or antifungal medication. If the condition does not improve after using these medications, immunosuppressants may be prescribed.
Immunosuppressants work by suppressing immune system responses, thereby disrupting the process of inflammation. There is, however, a risk of side effects. These may include:
- Skin rash
- Loss of appetite
- High blood pressure
In rare cases, surgery may be required to treat uveitis. This will typically be the case if the condition recurs frequently or if it is particularly severe.
The surgical procedure used to treat uveitis is called a vitrectomy. During the procedure, the substance that fills the interior of the eye, the vitreous, is removed and temporarily replaced with air, gas or a liquid substitute. Eventually, the eye will naturally replace the substance by itself.
A vitrectomy can be carried out using either local or general (patient is asleep during the procedure) anesthetic and – like any surgical procedure – comes with some risk of complications.