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). People often refer to conjunctivitis as red eye. Other symptoms of conjunctivitis include itchiness and watering of the eyes, and sometimes a sticky coating on the eyelashes (if it’s caused by an allergy). Conjunctivitis can affect one eye at first, but usually affects both eyes after a few hours.
The conjunctiva can become inflamed as a result of:
- a bacterial or viral infection – this is known as infective conjunctivitis
- an allergic reaction to a substance such as pollen or dust mites – this is known as allergic conjunctivitis
- the eye coming into contact with things that can irritate the conjunctiva, such as shampoo or chlorinated water, or a loose eyelash rubbing against the eye – this is
- known as irritant conjunctivitis
The symptoms of conjunctivitis will depend on what’s causing the condition.
However, the two main symptoms are usually:
- eye redness – as a result of the inflammation and widening of the tiny blood vessels in the conjunctiva (the thin layer of cells covering the front of the eyes)
- a discharge – the conjunctiva contains thousands of cells that produce mucus and tiny glands that produce tears – inflammation causes the glands to become
- overactive, so that they produce more water and mucus
Only one eye tends to be affected at first, but symptoms usually affect both eyes within a few hours.
Once medication has been prescribed and given for at least 24 hours. Read more about this illness at the NHS website.