What is Conjunctivitis?

Major Causes of This Common Eye Complaint

Jun 23, 2009 John Richard Roberts

Conjunctivitis is not normally serious but can be unpleasant. It has a variety of causes the most common being due to an infective agent such as a virus or bacterium.

Conjunctivitis, also known as pink eye, is one of the most common eye complaints accounting for around 30% of all eye problems seen by doctors.

The condition describes inflammation of the conjunctival membrane which covers a large part of the visible surface of the eye.

Anatomy and Function of the Conjunctiva

The conjunctiva are a specialised type of epithelial tissue known as a mucous membrane. They cover the white part of the eye and fold back to line the inner parts of the eyelids. They form a continuous membrane with the epithelium covering the cornea: the transparent part of the eye which covers the lens.

They produce tear fluid from accessory lacrimal glands (the bulk of tears coming from lacrimal glands at the nose side of the eye). The conjunctiva also produce mucous. Both of these fluids lubricate the eye and help wash away foreign bodies. They also have an important immune function in that they contain antimicrobial substances.

Clinical Features of Conjunctivitis

These vary according to the cause and severity of inflammation. The white of the eye becomes red either in part, at the angles of the eye for example, or all over. If the cause is bacterial, pus is normally produced leading to sticking eye lids especially first thing in the morning.

Itching is common and so is the feeling of grit in the eyes. Vision is seldom affected in uncomplicated cases and photophobia (pain or discomfort in bright light) is not particularly common.

Causes of Conjunctivitis

Infection is the most common followed by allergic and irritative causes. Occasionally conjunctivitis can be a feature of some types of systemic illness. In general, infective causes of conjunctivitis are associated with swelling of the lymph glands just in front of the ear and more often than not both eyes are affected

• Bacterial infection: mostly by staphylococcal or streptococcal organisms. Itching and pus are normally present. Newborns can present with conjunctivitis caused by the gonorrhoea bacterium or chlamydia passed to the baby from the mother. Bacterial conjunctivitis is treated with antibiotic drops.
• Chlamydia infection: usually associated with sexually transmitted disease. Little watery pus only. A particular form of chlamydia infection, trachoma is a major cause of blindness throughout the world. Treated with antibiotics.
• Viral infection. Watery discharge only and usually much itching. Several viruses can be responsible including herpes. May follow throat or chest infection. No treatment is available but sometimes antibiotic drops are used to prevent subsequent bacterial infection.
• Allergic: A little watery discharge is present with usually much itching. Allergy may be due to many things e.g. pollen, cosmetics.
• Irritant; any foreign body, dust and chemicals can inflame the conjunctiva. Damage to the conjunctiva from irritants can make it susceptible to infection.
• Systemic disease: Reiter's disease (a type of arthritis) and some other autoimmune diseases may give rise to conjunctivitis.

Complications of Conjunctivitis

Conjunctivitis is usually either self-limiting or responds well to medication; however very occasionally potentially serious problems can arise. If untreated trachoma can lead to entropion – turning in of the eyelids with the eyelashes scratching the cornea.

Sometimes the infection can involve the cornea and cause scarring which may affect vision. Neonatal conjunctivitis caused by gonorrhoea or chlamydia is serious and requires urgent treatment.

Self-help for Conjunctivitis

Bathing the eyes in warm saline can be soothing and proprietary drops can be obtained which keep the eyes lubricated. The most important thing in cases of infective conjunctivitis is hygiene. Not sharing towels and frequent hand washing will help prevent the spread of infection.

This article is for information only. If you have any health concerns you should consult your doctor.

Resource

Conjunctivitis by Silverman and Bessman. Pub Medscape June 2009

A Dictionary of Symptoms by Joan Gomez. Pub. Granada

Human Physiology: The Basis of Medicine by Pockock and Richards Pub OUP 1999

The copyright of the article What is Conjunctivitis? in General Medicine is owned by John Richard Roberts. Permission to republish What is Conjunctivitis? in print or online must be granted by the author in writing.

Conjunctivitis