Iritis is the name given to the inflammation of the iris (the coloured circular muscle in the front part of the eye) that is usually not related to any infection.
Symptoms include reddened appearance of the sclera (the white of the eyeball), blurring of vision and intolerance to bright lights (photophobia). Usually, only one eye is affected at a time. Iritis is also known as acute anterior uveitis.
What causes iritis?
Iritis is often idiopathic, that is, it occurs spontaneously without any known cause, although some forms of iritis may be attributed to genetic, immune or infectious reasons. Up to 20% of all iritis cases are associated with blunt trauma of the eye.
Many cases of nontraumatic iritis are due to certain systemic diseases. These include ulcerative colitis, lupus erythematosus and rheumatoid arthritis. Some specific infections such as HIV/AIDS, herpes simplex, varicella-zoster virus and syphilis can also cause significant iritis.
The symptoms of iritis are related to the irritation of the ciliary nerves causing ciliary muscle spasm (causing eye pain). Ciliary spasm irritating the ophthalmic branch of the trigeminal nerve causes photophobia. As a consequence of increased permeability of the blood vessels of the eye, white blood cells can enter the aqueous humor in the anterior chamber, causing a cloudiness or blurriness of vision which is called the flare, and is characteristically seen on slit lamp examination of the eye.
Both acute and chronic forms of anterior uveitis are known to occur, with the chronic form presenting with milder symptoms except during acute exacerbations.
How is iritis treated?
It is important to first evaluate the cause of the iritis before beginning treatment. Any underlying cause should obviously be treated. However, most cases of iritis are idiopathic, and therefore other treatment strategies are employed.
In the case of idiopathic acute iritis, the treatment strategy is to target the inflammation. Usually, drugs that dilate the pupils (cycloplegics) are administered to prevent pupillary spasm, which could cause pain. In addition, topical steroids, such as prednisolone, are often used to reduce the inflammation. Steroid administration could have side effects, such as raised intraocular pressure and cataract formation; however, potassium-sparing drugs can be used in combination with long-term steroids to prevent any vision loss.
With the appropriate treatment strategy, supervised by an ophthalmologist, the prognosis is relatively good. If steroids are administered, careful monitoring for any changes in the intraocular pressure or cataract formation is crucial for the first 48 hours to prevent vision loss. Improper use of steroids following a wrong diagnosis can lead to the degeneration of the optic nerve, which could result in irreversible vision loss. Therefore, diagnosis should be made carefully by specialists in this field, and steroids should be used only in severe cases, with careful monitoring.