Conjunctivitis, What Is It?

Viral Conjunctivitis, Bacterial And Alergic Conjunctivitis

Conjunctivitis - or 'pink eye' as it is sometimes called - is the term used for redness and irritation of the surface of the eye and eyelids. One or both eyes may be affected.

The eyes and eyelids are very sensitive to a number of irritants; either infections (such as bacteria and viruses) or non-infectious substances (such as pollen or chemicals).

Conjunctivitis very common in childhood and it is usually classified and treated according to whether it is due to an infection or not.

What Causes Conjunctivitis?

Conjunctivitis is caused either by infections (infectious conjunctivitis) or non-infectious substances (non-infectious conjunctivitis).

Infectious Conjunctivitis has two main causes - bacteria and viruses.

Bacterial conjunctivitis is caused by bacterial infections - usually either streptococci, staphylococci or pneumococci. These are contagious infections, and are spread by touch.

Viral conjunctivitis is usually seen along with typical symptoms of a cold, and the symptoms may differ very slightly from a bacterial infection (see below). Viral conjunctivitis is not as contagious as the bacterial form.

Non-infectious Conjunctivitis Has Three Main Causes

The first is allergic conjunctivitis, produced by substances that cause an allergy (such as pollen and animal fur). The second is chemical conjunctivitis, this is when an irritating substance comes into contact with the eye (such as household sprays or smoke). Eye make-up, for example mascara, can cause symptoms.

The third form of non-infectious conjunctivitis is rare, and is due to an underlying illness. For example, inflammatory bowel disease and rheumatoid arthritis may sometimes cause this rare form of conjunctivitis.

Sometimes red eyes can be caused by another condition. Occasionally the whites of a person's eyes can suddenly become bright red, but this is not due to a conjunctivitis. This is due to some of the tiny blood vessels under the whites of the eyes breaking when under pressure. This pressure can be caused by laughing, vomiting or even bending the head forwards. It is called a sub-conjunctival haemorrhage. While this condition looks impressive (and worrying), it needs no treatment and will settle by itself.

What Are The Signs And Symptoms Of Conjunctivitis?

In bacterial conjunctivitis there is usually eye soreness or pain, with swelling and redness of the affected eye. There is a discharge from the corner of the eye, usually coloured greenish-yellow. The discharge is seen most commonly on waking. This discharge can 'stick' the eyes shut, sometimes to the concern of a child, but is easily cleared with a warm cloth.

Viral conjunctivitis causes the same sort of eye irritation but the discharge is more watery or clear rather than coloured.

With the non-infectious types of conjunctivitis, an allergic reaction causes considerable itching of the eye, often with much rubbing. This rubbing of eye only makes the symptoms worse. There may be a runny nose, sneezing and a sore throat associated with it too as part of the allergic reaction. Similar symptoms occur when the conjunctivitis is due to a chemical irritation or underlying disease too.

However, if the conjunctivitis persists for a long time, it suggests that the cause may be an underlying disease.

Will I have Any Tests Or Investigations?

Doctors usually diagnose which type of conjunctivitis is present from the history and examination alone and rarely perform tests. In babies or children who have a persisting conjunctivitis or eye discharge, eye swabs may be taken to identify the organism that has infected the eye.

What Treatment Might I Need?

This depends on the underlying cause. 

In bacterial conjunctivitis, antibiotic eye drops or ointments are usually prescribed - usually chloramphenicol. Regular eye bathing with warm water, using a different cloth for each eye, is also recommended.

Note: It is important to use the eye treatment prescribed only for the person it was prescribed for. There are two important reasons. First, the medication will go out of date. Second, old bottles and tubes that have been used by one infected person may have been contaminated and this infection could be passed to the next person who uses that bottle or tube.

The easiest way to apply drops to a child is to lie the child down flat, ask them to shut their eyes and put the drops into the inner corner of the eye, next to the nose. The drops will form a tiny pool there. Ask the child to open their eyes, and the drops will then flow easily into the eye without worrying the child.

If your doctor thinks that the bacteria causing the conjunctivitis are part of a more general infection such as tonsillitis or an ear infection, the doctor will usually prescribe oral antibiotics rather than eye drops or ointments in order to treat the general infection.

In viral conjunctivitis there is no need for any anti-bacterial treatment, so no drops or ointments will be prescribed. All that will be needed is for the person with conjunctivitis to maintain simple eye hygiene, such as washing and drying each eye with a different cloth. Any flu-like symptoms, such as a runny nose, should be treated in the normal way.

With allergic conjunctivitis, the allergic symptoms are treated by placing cool cloths on the eyes regularly, and by using non-sedating anti-histamine eye drops or tablets. These eye drops or tablets can be obtained either over the counter from your local pharmacist or from your doctor.

Conjunctivitis caused by chemical irritation should always be first treated by very thoroughly washing the eyes for 5 to 10 minutes with large quantities of water. The person should then visit their doctor for a medical opinion.

What course will the illness follow?

Most cases of bacterial conjunctivitis will start to settle within 24 hours of beginning treatment, and the usual length of treatment is 3 to 5 days. Viral infections settle along with the underlying viral symptoms, typically between 2 and 6 days after their onset.

Can I do anything to help myself?

If you have a red eye that is discharging fluid, you should try to resist rubbing your eyes and you should seek medical advice. It is important not to rub the eye because bacterial infections are highly infectious and you may easily transfer the infection to your other eye.

Make sure you use your own personal towel and flannel so that others are not infected, and bathe the eye regularly. Remember to wash your hands thoroughly each time after using the treatment. If you suffer from allergic conjunctivitis during certain seasons (for example, during the summer), it is often worth using antihistamine treatment throughout the allergic season to prevent attacks.

Tell Your Doctor

1. How long have you had your symptoms?
2. Do you get symptoms like this regularly?
3. Do your eyes itch rather than hurt?
4. Does anyone else in your family or who you work with have a similar problem?
5. Did one eye have symptoms before the other?

Ask your Doctor

1. Am I allowed to wear my contact lenses?
2. If my baby has a conjunctivitis, have they caught it from me?
3. What is the right way to bathe my eyes?
4. How long should I leave it before returning to see you if my symptoms
do not clear?
5. How long will my eye drops last before needing to be thrown away?

By Dr Roger Henderson, MB BS, LMSSA.

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