Conjunctivitis: Eye Disease

The white of the eye and the inner surfaces of the lids are covered by a transparent membrane called the conjunctiva. Conjunctivitis is inflammation of the conjunctiva.

There are two main types of conjunctivitis allergic and infective. Allergic conjunctivitis happens when the immune system of your body attacks something that is not really harmful, such as pollen or make-up, and causes inflammation. Infective conjunctivitis is caused by viruses or bacteria infecting your eye. The immune system fights it, causing swelling. Infection is the most common cause of conjunctivitis. Conjunctivitis caused by an infection usually clears up on its own after a few days.

Conjunctivitis is sometimes called pink eye because the blood vessels in the eye are irritated and become enlarged, making the eye look red or pink.

Symptoms:
Symptoms can be similar for both infective and allergic conjunctivitis. In allergic conjunctivitis, both eyes are usually affected at the same time. In infective conjunctivitis, the infection may start in one eye, but it usually spreads to both.

Your symptoms may include:
• Reddening of the affected eye - this happens as a result of the irritation and widening of the tiny blood vessels in your conjunctiva,
• watering eyes - the conjunctiva contains thousands of cells that produce mucus and tiny glands that produce tears. Irritation causes these to become overactive, so they water and leak mucus,
• scratchy, gritty feeling in the eyes,
• swollen eyelids,
• sticky feeling - it may be hard to open your eyes in the mornings,
• slight soreness - if you have worsening pain, contact your GP.
In infective conjunctivitis, the mucus coming out of your eyes often contains many white cells from the blood (pus cells). The pus tends to clump together on the lashes, making them stick together.

Causes:
Conjunctivitis is most commonly caused by infection. Almost any germ, whether a bacterium or a virus, may be responsible. Some are more dangerous than others. The common cold can cause conjunctivitis, spreading from the mouth and nose to the eyes, but this is usually far less severe than infection of the eyes with chlamydia or herpes. However, conjunctivitis caused by the common cold is very infectious and can spread rapidly between people. Other bacteria that commonly cause conjunctivitis include staphylococci, streptococci and haemophilus bacteria.

The most common cause of allergic conjunctivitis is hypersensitivity to pollen (hay fever). The pollen irritates the eye and can cause the conjunctiva to swell. Occasionally this can lead to extreme swelling and bulging of the eye membrane.

Conjunctivitis can also result from a wide range of other causes, including:
• Chemicals, dusts, liquids, gases and other environmental contaminants, which can cause an allergic reaction – one of the most common causes is the chemicals found in swimming pools,
• radiation - especially the ultraviolet in sunlight,
• too much wind blowing on your eyes, and
• irritation from eye make-up.

If you wear contact lenses these can cause conjunctivitis if they become contaminated with bacteria or, rarely, tiny creatures called amoeba. This should not happen if your lenses are stored and handled correctly. It is particularly common if you wear occasional decorative contact lenses, as you may not have been properly trained in hygiene and handling of your lenses.

Treatment:
In most cases the diagnosis of conjunctivitis is made from visible symptoms, particularly swelling and redness of your eye. Mild infections may not need treating and will clear up on their own. Our tears contain chemicals that will fight infections, but if your symptoms get worse or do not improve, treatment should be considered. It can also be difficult to tell the difference between allergic and infective conjunctivitis (which is contagious). In this case only an eye specialist can determine if it is bacterial, viral, or an allergic reaction.

Prevention:
• Avoid rubbing your eyes with unwashed hands,
• if you have conjunctivitis, wash your hands after touching your eye,
• do not share towels or flannels with a person who has conjunctivitis,
• always follow strict hygiene measures with contact lenses, and make sure you know how to store them properly - your optician will be able to give you all the information you require, but it is important to seek advice even if you only use lenses for cosmetic reasons (for example, to change your eye colour),
• if you have allergic conjunctivitis, try to prevent future attacks by avoiding the cause of the allergy - alternatively, your eye doctor may be able to prescribe antihistamines to reduce the over-reaction of your immune system, and
• when you have a cold or flu, always wash your hands after blowing your nose, and avoid touching your eyes, to prevent cross-infection.