Conjunctival disorders

What are disorders of the conjunctiva?

The conjunctiva is the thin, practically transparent membrane that covers the white parts of the eye (the sclera) and lines the inside of the eyelid. It does not cover the cornea, the clear covering on the front of the eye. Many different conditions can affect the conjunctiva. Some are common and cause mild symptoms – while others are rare and can be sight-threatening.

The conjunctiva is made of three parts:

• Palpebra conjunctiva: The part lining the inside of the eyelids.
• Bulbar conjunctiva: The part covering the eyeball to protect the white of the eye.
• Conjunctiva fornix: The piece that joins the palpebra and bulbar conjunctiva together to form one continuous piece of tissue.

The conjunctiva has many essential functions that play a vital role in keeping the eye healthy:

• Protection: providing a barrier to prevent foreign bodies from getting in that could cause irritation or damage, such as bacteria, viruses or allergens.
• Nourishment contains a network of blood vessels circulating oxygen and nutrients throughout the eye.
• Lubrication: Produces the mucus layer that forms part of the tear film, which lubricates the eye’s front surface and inner eyelids.

What are the most common disorders of the conjunctiva?

The most common disorders that affect the conjunctiva are pink eye (conjunctivitis) and subconjunctival haemorrhage:

• Conjunctivitis – or inflammation of the conjunctiva – is when the small blood vessels in the conjunctiva become swollen and irritated, causing the whites of the eyes to appear red or pink. The condition is most commonly caused by a viral infection but can also be caused by bacteria, allergens, irritants, and rarely by parasites and fungi.
• Subconjunctival haemorrhage is a broken blood vessel in the conjunctiva, causing blood to leak underneath the tissues. These appear as bright red spots on the eye – which can look alarming, but in most cases, they don’t cause any symptoms or need treatment.

What causes disorders of the conjunctiva?

The conjunctiva can become damaged through injury, infection, chemical irritation, allergic reactions, dryness – and, rarely, cancers. The exact causes of a conjunctival disorder will depend on the type of the condition but can include:

• 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: a person’s 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.
• Dry eyes: this condition may occur when the tears aren’t providing adequate lubrication to the eyes – for example, if the eyes aren’t producing enough tears or poor-quality tears – which can lead to inflammation and damage to the eye’s surface. Dry eyes can feel uncomfortable and can sting or burn. A person may be more likely to experience dry eyes in certain situations, such as in an aeroplane or air-conditioned room.
• Foreign objects: things that enter the eye from outside the body – such as dirt, sand, grit, glass or cosmetics – may enter the conjunctiva as a result of everyday activities or accidents. Depending on what they are, these foreign objects may cause damage or infection.
• Immune-mediated diseases: Certain immune-mediated conditions (e.g. mucous membrane pemphigoid, Steven-Johnson syndrome, and epidermolysis bullosa) that target the conjunctiva and other mucous membranes/linings in the body can result in conjunctival inflammation and progressive scarring.
• Injury: trauma – such as from rubbing the eye too hard or scratching it while removing contact lenses – can cause damage to the conjunctiva.
• Tumours: While most conjunctival growths are benign, they may irritate the eye and obstruct the tear duct. However, some rare types of cancer are malignant and can be life-threatening if the disease spreads to other parts of the body.
• Viruses: Viral conjunctivitis is caused by a viral infection, such as with adenoviruses and herpes simplex virus (the same virus that causes “cold sore”) that tend to attack the cornea as well as the conjunctiva. A person 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. But strict hygiene measures, such as frequent hand washing, can help to limit its spread.

What are the symptoms of disorders of the conjunctiva?

Symptoms of conjunctiva disorders may range from redness and irritation – to discharge, swollen eyelids, a burning sensation and pain. A person’s exact symptoms will depend on the type of condition and its causes but may include:

• Eye redness: discolouration or redness in one or both eyes.
• Watering: excessive tears are produced by one or both eyes.
• 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.
• Pain: such as stinging or burning in one or both eyes.
• Itching: intense itchiness which can occur in one or both eyes. This is the most common presenting symptom of allergic conjunctivitis.
• Gritty feeling: a sensation of having something in the eye or eyes.
• Sensitivity to light: discomfort in the eye or eyes in response to bright light – also called photophobia.
• Swollen eyelids: localised swelling that can occur in one or both eyes.
• Reduced vision: such as blurred or double vision or eye fatigue.

Some conjunctival conditions – including injury, allergy and infection – can 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.

On a global scale, a major cause of scarring of the conjunctiva and blindness is trachoma, which is rare in the UK but affects many millions of people in less developed countries around the world.

Treatments for disorders of the conjunctiva

Treatment for conjunctival disorders is often focussed on symptom relief. A person may be recommended to use lubricating eye drops (or artificial tears), clean their eyelids with a wet cloth, and to apply cold or warm compresses several times daily. But they can sometimes also be prescribed medications – such as antibiotics, steroids and other anti-inflammatories, and eye drops. On rare occasions, a person may be offered surgery to remove a tumour.

If a person is a contact lenses user, they will be advised to stop wearing them until their symptoms have cleared up – and to dispose of any soft lenses that they have already worn. People should also dispose of any eye makeup they were using before their illness developed.

Treatment for a disorder affecting the conjunctiva will depend on the condition and the exact symptoms:

• Viral conjunctivitis: a person’s symptoms will often gradually clear on their own after the virus has run its course. This typically can take two to three weeks. Antiviral medications may be an option in certain circumstances, such as infections caused by the herpes simplex virus.
• Bacterial conjunctivitis: bacterial infections may require treatment with antibiotic drops to clear the condition.
• Allergic conjunctivitis: treatments for allergic conjunctivitis include many different types of eye drops or pills – which may either 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 their problems may also help reduce the severity of their symptoms.
• Subconjunctival haemorrhage: these are typically harmless and will usually resolve within a week or two without any treatment.
• Dry or irritated eyes: inflammation of the conjunctiva related to exposure to external agents – such as for example chemical or air conditioning – are usually managed with artificial tears.
• Tumours: treatment will depend on the type of growth and its location, but can include surgical removal if necessary.
• Immune-mediated diseases: treatment will often involve immunosuppression, with topically with eye drops (for mild disease) and/or systemically with tablets (for more severe disease).

Latest Research on conjunctival disorders

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

Conjunctival disorders clinical trials

You could play an important part in eye research by being a participant in a clinical research study that may benefit many people. You could even help shape clinical research by becoming more actively involved and having a say. Patients, carers, or anyone with an interest can help.

What are clinical trials?

Clinical trials are research studies that find out if a medical strategy, treatment, or device is safe and effective for humans. They are a key research tool for improving medical knowledge and patient care. The people who carry out research are mostly the same doctors and healthcare professionals who treat people. Their aim is to find better ways of treating patients and keeping people healthy.

Taking part

Here are some ways to find out about research projects and clinical trials that you can get involved in.

UK Clinical Trials Gateway

The UK Clinical Trials Gateway, run by the National Institute for Health Research (NIHR), provides easy-to-understand information about clinical research trials running in the UK and gives to a large range of information about these trials. It is designed to enable patients and clinicians to locate and contact trials of interest. Visit their website and select the eye condition that you are interested in.

NIHR Clinical Research Network Portfolio

The NIHR Clinical Research Network Portfolio is a database of high-quality clinical research studies in England, Northern Ireland, Scotland and Wales. Within this, the Ophthalmology Specialty Group supports a national portfolio of research studies in ophthalmology and the vision sciences. See their website for details.

If you wish to join a trial it is always best to discuss this with your doctor or clinical team first.

Last updated January 2023