Conjunctivitis is a condition that occurs when the conjunctiva (a thin layer of cells covering the front of your eyes) becomes inflamed.
The three most common causes of this inflammation are:
These arediscussed in more detail below.
Eye infections are most commonly caused by:
Viral conjunctivitis causes a watery discharge, while the discharge from bacterial conjunctivitis contains pus. An eye swabcan also determine the cause of the infection (read more about diagnosing conjunctivitis ).
You're more likely to develop infective conjunctivitis if you've been in close contact with someone who's already infected with it.
It's therefore very important to wash your hands thoroughly after coming into contact with anyone who has infective conjunctivitis. You should also avoid sharing pillows or towels with anyone with the infection.
You may be more at risk of getting infective conjunctivitis if:
Allergic conjunctivitis is caused when your eyes come into contact with an allergen (a particular substance that causes your immune system to react abnormally). This is known as an allergic reaction.
There are four main types of allergic conjunctivitis:
Seasonal and perennial allergic conjunctivitis are usually caused by:
These types of conjunctivitis are more common in people who also have other allergies, such as asthma ,and often occur with allergic rhinitis .
Contact dermatoconjunctivitis isusually caused by eye drops, but it can also be caused by make-up or chemicals.
Giant papillary conjunctivitis is caused by:
Giant papillary conjunctivitis is estimated to affect around 1-5% of people who use soft contact lenses and 1% of people who use hard contact lenses.
Irritant conjunctivitis can have a wide range of potential causes. Some common causes include:
Conjunctivitis is a common condition that causes redness and inflammation of the thin layer of tissue that covers the front of the eye (the conjunctiva).
Read about the symptoms of conjunctivitis. The two most common symptoms are eye redness and a discharge.
Find out what causes conjunctivitis. The three most common causes are infection, allergic reaction or eye irritation.
Find out how conjunctivitis is diagnosed. Your GP will ask you about your symptoms, examine your eyes and may recommend further tests, such as a swab test.
The recommended treatment for conjunctivitis will depend on whether it's caused by infection, an allergic reaction or an irritant, such as a stray eyelash.
Complications of conjunctivitis depend on whether the condition is an infection (infective conjunctivitis) or an allergic reaction (allergic conjunctivitis).