Conjunctivitis
Conjunctivitis is inflammation of the transparent layer (the conjunctiva) that covers the white of the eye. It can cause redness, discharge from the eye, swelling of the eyelid, and sore or itchy eyes.
Causes of conjunctivitis
The most common cause of conjunctivitis is an infection of the eye. This can be caused by many types of viruses or bacteria.
Allergies are also a common cause of conjunctivitis. Typical allergic reactions include pollen (hay fever), cosmetics or animal fur.
Infective conjunctivitis
Infective conjunctivitis is more common in children than in adults. Viral conjunctivitis often occurs with mild viral illnesses. It is often caused by a virus called an adenovirus, the same type of virus that causes the common cold. It is sometimes associated with more serious illnesses, such as measles.
Bacterial conjunctivitis often follows viral conjunctivitis, or after rubbing the eyes following close contact with someone else with infective conjunctivitis. Common causes of bacterial conjunctivitis include Staphylococcus aureus and Streptococcus pneumoniae.
Sometimes newborn babies develop conjunctivitis as a result of the spread of infection from the mother´s cervix (the neck of the womb) or vagina during birth. Any parent who suspects their newborn baby has conjunctivitis should contact their GP, health visitor or midwife.
A serious form of bacterial conjunctivitis can be caused by Neisseria gonorrhoea, which causes the sexually transmitted infection gonorrhoea. This type of infection is usually spread from the genitalia to the hands and then to the eyes.
Allergic conjunctivitis
Seasonal allergic conjunctivitis (hay fever conjunctivitis) is more common. It generally occurs in the spring months, when it´s caused by grass pollen, or in the late summer months, when it´s often caused by weeds.
Perennial (all year round) allergic conjunctivitis can be caused by house-dust mites, pets or mould.
Conjunctivitis is sometimes caused by a type of eye-makeup you have not used before. However, allergies can also spontaneously develop to a cosmetic that has previously been used with no problem.
Symptoms
Conjunctivitis causes soreness and redness that affects either one or both eyes. Symptoms can also include inflammation of the skin of the eyelids, with redness, irritation, drying and flaking of the skin around the eyes.
Allergic conjunctivitis usually affects both eyes at the same time, and often causes itchiness or a feeling of grittiness or burning.
People who have allergic conjunctivitis associated with hay fever almost always have other features of allergy, such as sneezing, a runny, itchy nose and itchiness at the back of the throat. Symptoms usually last for four to six weeks and often vary during the pollen season according to the weather conditions (worse on hot, dry and windy days).
Bacterial conjunctivitis usually begins in one eye and often spreads to the other. If a bacterial infection is the cause, there may be some yellow pus-like discharge from the eye.
Viral conjunctivitis is more likely to cause a watery discharge that can be crusty in the morning but is not pus-like. Viral conjunctivitis usually begins in one eye then affects the other eye within 24-48 hours. There may also be cold-like symptoms, such as fever and a sore throat. Like colds, the symptoms tend to get worse over the first few days, and then gradually improve over the next two to three weeks.
One type of viral conjunctivitis, called infectious keratitis, can cause a feeling of having something in the eye, which can be so severe that it is difficult to open the eyes. This condition can result in permanent damage to vision, and anyone with this sensation should seek medical advice.
When to see a doctor
Visit your GP immediately if you have red eyes combined with any of the following symptoms:
- difficulty seeing
- a persistent feeling of having something in the eye, which interferes with the ability to open the eye
- there has been a severe blow to the head or another injury, such as a finger poke, fist or tennis ball in the eye
- sensitivity of the eyes to light
- severe eye pain
- severe headache
- nausea or vomiting
Anyone who wears contact lenses and gets red eyes and a discharge should stop wearing the lenses and seek medical advice.
Anyone who has the symptoms of conjunctivitis for more than a few days should visit their GP.
Diagnosis of conjunctivitis
Your doctor can usually tell the cause of conjunctivitis from your symptoms and an examination. He or she may shine a light in your eye to check how it reacts, and may ask you to read something to check whether your vision is impaired.
The doctor may take swabs from the eye to test for bacteria, but this is not always necessary.
In some cases the doctor will refer you to an ophthalmologist (a doctor who specialises in treating eye conditions).
Treatment for conjunctivitis
Self-help
Irritation in the eyes can be partially relieved by bathing them with preparations available over the counter from a pharmacist. These often contain witch hazel, which is thought to have soothing properties.
It is important to avoid rubbing your eyes as this makes the inflammation worse. It is also important in bacterial conjunctivitis that you don´t spread the infection from one eye to the other or to other people. You should not touch the affected eye. Any towels used to dry the affected eye after washing should not come into contact with the other eye or be used by other people.
The most important treatment for allergic conjunctivitis is to avoid the substance that causes the allergy. This may be easy if the cause is animal fur or cosmetics, but more difficult if it is pollen. However, keeping windows and doors closed on days when the pollen count is very high can often help reduce symptoms.
Medicines
Bacterial conjunctivitis can be treated with antibiotic eye drops or ointment, which can only be obtained with a prescription from your doctor.
Allergic conjunctivitis is treated with eye drops, which can be obtained with a prescription from your doctor, or bought over-the-counter from a pharmacist. Always follow the instructions that come with the medicine. Generally, the drops should be applied to both eyes. It is important that eye drops are applied regularly throughout the hay fever season, regardless of how severe the symptoms are on any particular day.
Viral conjunctivitis does not need specific medical treatment and will clear up on its own in two to three weeks.