Anterior uveitis is a non-contagious condition where the front part of the eye becomes inflamed. The causes vary, and the symptoms are ‘nonspecific’, which means they are similar to those of other eye conditions. That’s why it’s important to see an optometrist immediately in case of eye pain or unexpected vision problems.

Treatment is especially important as it causes most cases to improve. However, if left untreated, anterior uveitis can lead to permanent damage or even loss of vision. An eye specialist can make a correct diagnosis based on an examination, medical history, and diagnostic tests.

What is anterior uveitis? Why does it occur?

Anterior uveitis (also called iritis, cyclitis, or iridocyclitis) is an inflammation of the front part of the eye. It involves the iris and ciliary body, a structure that helps your eye to focus by altering the shape of the lens. The iris is the coloured part of your eye.

The ciliary body also secretes aqueous humour, a fluid that provides nutrients to keep the eye healthy. If left untreated, uveitis can lead to many complications, including cataract, glaucoma, and retinal detachment⁴.

The condition responds well to treatment but is frequently known to recur². It occurs predominantly in young and middle-aged adults (ages 20 to 50). Typically, one eye is affected, but both eyes may sometimes be involved either at the same time or one after the other³.

There are several reasons why an inflammatory response may occur inside the eye. Possible causes of anterior uveitis include⁴:

• Injury or trauma (for example, from a foreign body in the eye or from being hit in the eye).
• In association with infections such as herpes (shingles), cytomegalovirus (CMV), syphilis, and tuberculosis.
• Autoimmune disorders such as rheumatoid arthritis, sarcoidosis, and ankylosing spondylitis.
• In people with certain genes (for example, HLAB27) who are at higher risk³.

Sometimes, cases of anterior uveitis are known as ‘idiopathic’, which means that an underlying cause could not be identified.

Uveitis can also occur elsewhere in the eye, including in the middle of the eye (‘intermediate’), at the back of the eye (‘posterior’), and in all layers of the eye’s uvea, which includes the iris and ciliary body (‘panuveitis’). However, anterior uveitis is the most common form. Most cases of anterior uveitis take 6-8 weeks to subside, but severe symptoms usually disappear within a few days of starting treatment.

What are anterior uveitis symptoms?

If you suspect you have anterior uveitis, you should be treated promptly. The symptoms of this condition can develop quickly over a few hours or more gradually over several days. The most common signs and symptoms are:

• A red, painful, or inflamed eye
• Blurred vision
• Photophobia (severe light sensitivity)
• Having an irregular-sized or small pupil
• Seeing coloured halos around lights

A diagnosis will be made based on your medical history and an examination with a microscope called a slit lamp, which is an instrument specifically designed for examining eyes. If your doctor suspects that the condition has affected other parts of your eye, they may do what is called a ‘dilated eye exam’.

This involves the use of eye drops that dilate the pupil to allow a detailed examination of the internal structures of the eye. A common side effect of the eye drops used can be temporarily blurred vision. Your vision will usually return to normal within 2-4 hours. Additional blood tests and/or imaging studies may be needed to investigate whether other health conditions may be at play, or to identify why you may be experiencing recurrent episodes of iritis.

What are anterior uveitis treatment options?

Anterior uveitis is usually treated with eye drops that contain:

• Steroids, to reduce inflammation
• Dilating agents, to make the pupils larger and relieve any pain you are experiencing
• Pressure-lowering drops, if intraocular pressure (IOP) within the eye is high

It is important to follow the doctor’s instructions exactly and self-medication is not advised. Steroid drops must be tapered gradually and cannot be stopped suddenly, however specific directions will depend on the length of your treatment. The types of drops you’re using may also be changed as your treatment progresses.

You may also be given different eye drops to those used in any previous episodes of anterior uveitis, and this depends on the severity of your present condition and how frequently episodes have recurred.

Dilating drops cause temporary blurred vision and are often only needed in the early stages of treatment. This can make reading difficult, although moving around as you normally would is still possible. It is not possible, however, to drive, climb ladders, or operate heavy machinery while using dilating drops. If these drops are needed in the longterm, they may be used at bedtime.

What’s the link between anterior uveitis and glaucoma?

One of the most common and serious complications of anterior uveitis is an increase in the pressure inside the eye (intraocular pressure). There are both direct and indirect reasons why this occurs.

Damage to the anterior chamber

Uveitis and its treatment can damage the normal structure of the eye, specifically the anterior chamber, which contains the aqueous humour, and angle, which refers to the angle between the iris and the cornea (the ‘window’ front part of your eye). Both uveitis and its treatment can also affect the production and outflow of aqueous humour, which disrupts the pressure within the eye.

Inflammation

Anterior uveitis is an inflammatory condition, and may cause an accumulation of inflammatory cells and debris in the trabecular meshwork, an area of tissue responsible for draining the aqueous humour, and swelling (oedema) of the ciliary body. Scar tissue formation may also lead to obstruction of the aqueous humour outflow.

Each of these scenarios may lead to an increase in intraocular pressure, which can cause glaucoma to develop. Glaucoma may also develop as a side effect of treatment, as steroid therapy for anterior uveitis can cause an increase in intraocular pressure⁵,⁶.

If you develop glaucoma as a result of anterior uveitis or its treatment, this can lead to a gradual but permanent loss of vision. Managing uveitic glaucoma is complex because there are numerous direct and indirect mechanisms involved, and your ophthalmologist must carefully distinguish the cause in each case and treat accordingly.

The goal is to prevent irreversible damage to the structures of the eye, including the optic nerve head. Fortunately, many effective treatments for anterior uveitis are available that allow patients to avoid complications such as glaucoma and maintain excellent vision.

Want to learn more about how glaucoma can develop? Explore our dedicated glaucoma resource for more information on glaucoma causes, glaucoma diagnosis, glaucoma treatments, and other linked health conditions.