Conjunctivitis

What is conjunctivitis?

Conjunctivitis – also called pink eye or inflammation of the conjunctiva – is one of the most common disorders of the conjunctiva. It happens when the small blood vessels in the conjunctiva become swollen and irritated, causing the whites of the eyes to appear red or pink.

The conjunctiva is a thin, almost transparent membrane that covers the white of the eye and lines the inside of the eyelid. It provides a barrier to prevent foreign bodies from getting in that could cause irritation or damage. It also contains a network of blood vessels circulating oxygen and nutrients throughout the eye. And it produces the mucus layer that forms part of the tear film, which lubricates the eye’s front surface and inner eyelids.

The other common disorder of the conjunctiva, which can also make your eye look red or pink, is a subconjunctival haemorrhage. This is a broken blood vessel in the conjunctiva, causing blood to leak underneath the tissues. These appear as bright red spots on the eye. It can look alarming, but in most cases, they don’t cause any symptoms or need treatment.

What causes conjunctivitis?

Conjunctivitis is most often caused by a viral infection but can also be caused by bacteria, allergens, irritants, and rarely by parasites and fungi.

• Allergens: Allergic conjunctivitis is an inflammatory response of the conjunctiva to an allergen, such as pollen, dust, or mould. It is not contagious and does not spread from person to person. Symptoms of the condition include red eyes, watery discharge, swollen eyelids, and intense itchiness, which usually affects both eyes at once. In severe cases, allergic conjunctivitis can also affect the cornea and the vision.
• Bacteria: Bacterial conjunctivitis starts with a feeling of grittiness and discomfort in the eye. A person’s eye will become red and begin to produce a thick discharge that may form a crust and cause the eyelids to stick together. The condition is very contagious and can spread easily from person to person. A disease called trachoma, which is caused by an infection of the conjunctiva with a bacterium called Chlamydia trachomatis, is a significant cause of preventable blindness in the world.
• Chemical irritants: Your eyes may react to exposure to certain chemical irritants – such as smoke from vehicles or chlorine in swimming pools. Common symptoms include redness, swelling, reduced vision, and pain.
• Immune-mediated diseases: Certain immune-mediated conditions (such as mucous membrane pemphigoid, Steven-Johnson syndrome, and epidermolysis bullosa) that target the conjunctiva and other mucous membranes in the body can result in conjunctival inflammation and progressive scarring.
• Viruses: Viral conjunctivitis is caused by a viral infection, such as with adenoviruses and herpes simplex virus (the same virus that causes “cold sores”) that tend to attack the cornea as well as the conjunctiva. You will experience redness, swelling, irritation, and excessive watering of the eye and eyelids. The condition is highly contagious, often starting in one eye and spreading to the other – and it is easily spread from person to person. 

What are the signs and symptoms of conjunctivitis?

Symptoms of conjunctiva disorders may range from redness and irritation to discharge, swollen eyelids, a burning sensation, and pain. The symptoms can vary but may include:

• Eye redness: discolouration or redness in one or both eyes.
• Watering: excessive tears are produced.
• Discharge: a thick discharge that may cause the eyelids to crust or stick together, making it difficult to open the eye or eyes after sleeping. This usually indicates an underlying cause of infection.
• Itching: intense itchiness in one or both eyes. This is the most common symptom of allergic conjunctivitis.
• Gritty feeling: a sensation of having something in the eye or eyes.
• Swollen eyelids: in one or both eyes.
• Sensitivity to light (photosensitivity): in some cases

Is conjunctivitis serious?

Conjunctivitis is usually not serious, but in serious cases the condition might cause the conjunctiva to become permanently scarred. The eyelids can become stuck to the eye and cause sight loss because of damage to the cornea. 

How is conjunctivitis diagnosed?

Diagnosis of conjunctivitis often involves a thorough examination of the eye as well as questions about what symptoms you have been experiencing. Additionally, a swab may be taken from the eye to identify any bacterial, viral, or fungal infections. For more severe or persistent cases, further tests like blood tests or biopsies might be required to identify underlying conditions.

What are the treatments for conjunctivitis?

You might be recommended to use lubricating eye drops (or artificial tears), clean your eyelids with a wet cloth, and to apply cold or warm compresses or flannels several times daily. 

• Treatments for viral conjunctivitis: Symptoms will often gradually clear on their own after the virus has run its course. This typically can take two to three weeks. Antibiotics will not help. Antiviral medications may be an option in certain circumstances, such as infections caused by the herpes simplex virus.
• Treatments for bacterial conjunctivitis: This may require treatment with antibiotic drops to clear the condition.
• Treatments for allergic conjunctivitis: There are many different treatment options, either eye drops or pills – which may be over-the-counter or prescription medications. These include artificial tears, medicines that help control allergic reactions, such as antihistamines, or those that help control inflammation, such as decongestants, steroids, and anti-inflammatory drops. Avoiding exposure to the specific allergen that is causing your problems may also help.

What can help conjunctivitis?

If you use contact lenses, you will be advised to stop wearing them until your symptoms have cleared up – and to dispose of any soft lenses that your have already worn. You should also dispose of any eye makeup you were using before the conjunctivitis started.

Bacterial and viral conjunctivitis are very contagious and can spread easily. Strict hygiene measures, such as frequent hand washing, can help to limit its spread.

What research is there into conjunctivitis?

Important areas for conjunctival research are to develop better treatments for inflammation and to replace or repair damaged tissue.

Fight for Sight's Research Strategy has pledged to spend over 20 million on pioneering eye research over the next five years. If you're interested in fundraising to help us fund cutting-edge research in this area find out how to get involved.