Swollen eyes and eye infections

Swollen, itchy eyes are no fun. Dr Sarah Brewer talks you through the causes, diagnosis and solutions.

If your eyes are red, swollen, itchy, watery or sticky and feel uncomfortably gritty, then you probably have conjunctivitis - an inflammation of the conjunctival membrane lining the eye and eye lids. Sometimes just one eye may be involved, but often, both eyes are affected. There are four main causes: allergy, autoimmune, infection and irritation. Some causes of a swollen, red, painful eye can cause permanent damage if left untreated, so it is important to have eye problems diagnosed as soon as possible.

Allergic conjunctivitis
One of the most common causes of allergic conjunctivitis is hayfever, triggered by pollen allergy, but dust mites, animal secretions, cosmetics and even contact lens solutions can cause allergic eye swelling and redness, too. Usual treatment is to avoid the trigger (if known) and to damp down the allergic reaction with antihistamine eye drops or tablets.

Autoimmune eye problems
Some people develop an auto-immune inflammation of the conjunctiva and other parts of the eye as a response to another infection (eg gonorrhoea, Chlamydia) elsewhere in the body. Red, swollen, painful eyes can also accompany an autoimmune condition such as rheumatoid arthritis or an inflammatory bowel disease. This form of red eye occurs when the body makes antibodies aimed against part of the eye. It appears to have a genetic link as it is most common in those inheriting a particular gene known as HLA-B27. It is treated with corticosteroid eye drops and/or tablets, but these are only prescribed where an eye infection has definitely been ruled out. This is because corticosteroids can make eye infections dramatically worse.

Infective conjunctivitis
Eye infections may be bacterial (eg Staphylococci, Streptococci, Haemophilus), viral (eg adenovirus, Herpes simplex) or due to Chlamydia ? a strange cross between a bacterium and a virus. Trachoma ? a Chlamydial eye disease common in some countries ? is one of the most common causes of conjunctival scarring and blindness world-wide. In the UK, it is most commonly seen in newborn babies infected during birth where their mother has undiagnosed Chlamydia (a sexually transmissible infection).

Bacterial and Chlamydial eye infections are treated with antibiotics (creams, drops and tablets). Mild viral conjunctivitis, such as that accompanying the common cold, may need no treatment (but still get it checked out by your doctor). More severe viral conjunctivitis due to the Herpes simplex virus, is treated with antiviral drugs.