What is conjunctivitis?

Conjunctivitis is sometimes also called pink eye. It occurs when the outer layer of the eye and the insides of the eyelids become inflamed. This may be caused by an infection with bacteria or viruses, or by allergens and other irritating substances that come into contact with the eye. The main symptoms of conjunctivitis are eyes that are red, swollen, watery and itchy.

Treatment for conjunctivitis can depend on what is causing the condition. Mild cases of conjunctivitis usually clear up on their own, while more serious cases can be cleared up with medicated eye drops or ointments prescribed by a doctor.

Allergens

An environmental substance that, although not harmful in itself, elicits a vigorous reaction from the immune system.

Causes

Conjunctivitis occurs when the thin layer of cells that line your eye and the insides of your eyelids, called the conjunctiva, become inflamed. There are several different types of conjunctivitis, which have different causes.

Types

Infective conjunctivitis

Infective conjunctivitis is an eye infection caused by bacteria and viruses. This type of conjunctivitis is contagious and can be easily spread to others. You may become infected if your eyes come into contact with fluid from an infected person.

Bacterial conjunctivitis

Some of the bacteria that commonly cause conjunctivitis are Streptococcus pneumonia, Haemophilus influenza, Staphylococcus aureus, Streptococcus pyogenes and Chlamydia trachomatis.

Viral conjunctivitis

Viral conjunctivitis can be very contagious. It is usually caused by adenoviruses, but can also be caused by the herpes simplex virus (HSV). In some cases conjunctivitis that is caused by HSV can cause ulcers to form on the inner surface of the eyelid. 

Allergic conjunctivitis

Allergic conjunctivitis is caused by an allergic reaction that occurs when the eye comes into contact with certain substances that cause your immune system to overreact. This leads to inflammation of the eye and results in conjunctivitis. Some of the common things that may trigger allergic conjunctivitis include pollen, dust mites and animal fur.   

Irritant conjunctivitis

Irritant conjunctivitis occurs when foreign bodies or chemicals get into your eye and cause inflammation. Substances that may cause irritation to the eye include shampoo, smoke, dirt or eyelashes.

Adenoviruses

A family of viruses that cause primarily respiratory diseases, conjunctivitis and gastroenteritis.

Herpes simplex virus

A highly contagious virus that gives rise to cold sores, genital infections, skin and eye lesions, and nervous system disorders. They commonly cause persisent infections.

Ulcers

An open sore in the skin or mucous membranes such as those of the stomach lining, intestine or mouth.

Signs and symptoms

The main symptoms of conjunctivitis include:

  • Red and irritated eyes;
  • Teary or watery eyes;
  • Itchy eyes;
  • Gritty feeling in the eyes;
  • Pus around the eyes;
  • Swollen eyelids, and;
  • Sensitivity to light;

The symptoms of conjunctivitis can last from a couple of days to around three weeks.

Conjunctivitis symptoms red, pussy, and and watery eyes.Conjunctivitis causes production of pus, swollen eyelids and red eyes. 

Pus

A bodily fluid that is the result of an inflammatory response at an infection site. Its colour can range from whitish to yellow to green, depending on the composition. Pus is mainly composed of dead bacteria, white blood cells and cellular debris.

Methods for diagnosis

To work out if you have conjunctivitis, your doctor will examine your eyes. Usually a diagnosis is based on your symptoms. Your doctor may also take a sample of fluid or pus from your eyes and send it for laboratory testing to work out what might be causing your condition.

Pus

A bodily fluid that is the result of an inflammatory response at an infection site. Its colour can range from whitish to yellow to green, depending on the composition. Pus is mainly composed of dead bacteria, white blood cells and cellular debris.

Types of treatment

Mild conjunctivitis usually gets better on its own without treatment. Some severe cases of conjunctivitis need medical attention. The type of treatment you need depends on what is causing your conjunctivitis.

Bacterial conjunctivitis

If you have mild conjunctivitis that is caused by a bacterial infection, your doctor may treat this by washing out your eyes and eyelids with a salt solution and administering antiseptic eye drops, such as propamidine isethionate. However, if your symptoms have not improved in 2-3 days, you are usually advised to return to your doctor. More severe cases may need to be treated with an antibiotic, such as chloramphenicol, which can be administered as eye drops or as an ointment.

Viral conjunctivitis

There is no specific treatment for most cases of conjunctivitis that are caused by a viral infection. Viral conjunctivitis usually clears up on its own within 2-3 weeks. There are some measures available that may help to relieve your symptoms, including washing the eyes and eyelids with a salt solution, or administering lubricating eye drops. Alternatively, eye drops containing naphazoline or phenylephrine may help to reduce some of the symptoms such as itching and swelling. 

If viral conjunctivitis is caused by an infection with herpes simplex virus, treatment may include an antiviral ointment, such as acyclovir, which is applied to the eye.

Allergic conjunctivitis

Allergic conjunctivitis is usually treated with medication to stop the allergic reaction and reduce inflammation. This may include antihistamines and mast cell stabilisers, such as sodium cromoglycate or ketotifen, which are usually administered as eye drops.

Irritant conjunctivitis

Irritant conjunctivitis is usually treated by washing the eyes and eyelids with a salt solution or administering lubricating eye drops.

Eye drops.Medicated eye drops are used to treat different types of conjunctivitis. 

Antihistamines

A substance that counters the physiological effects of histamine, a type of compound released by the tissues as an inflammatory response to an allergic reaction.

Herpes simplex virus

A highly contagious virus that gives rise to cold sores, genital infections, skin and eye lesions, and nervous system disorders. They commonly cause persisent infections.

Complications

Recognising the signs of conjunctivitis and seeking treatment from your doctor early are important in preventing any complications. If left untreated, conjunctivitis can affect the parts of your eye that are important for vision. Conjunctivitis caused by Chlamydia trachomatis, which is called trachoma, is the major cause of infectious blindness in the world. Trachoma is a chronic inflammation of the external lining tissue of the eye and eyelids. It can lead to the formation of ulcers and is a common cause of blindness in people who get the infection multiple times. This type of conjunctivitis is common in the indigenous population and in outback communities where there is poor hygiene. It can be spread through contact with other people who have the infection and by flies. 

Ulcers

An open sore in the skin or mucous membranes such as those of the stomach lining, intestine or mouth.

Prognosis

While conjunctivitis can sometimes be an annoying and painful condition, it is usually not very serious. With treatment, the symptoms usually only last several days to a few weeks.

Prevention

Conjunctivitis that is caused by bacteria or viruses is contagious, which means it can easily spread to other people. You may be able to reduce your chance of getting this type of conjunctivitis if you:

  • Wash your hands before touching any area close to your eyes;
  • Use clean hands to handle contact lenses;
  • Clean towels and face cloths regularly, and;
  • Do not share eye cosmetics, such as mascara.

Conjunctivitis may also be prevented by avoiding substances that cause you to have an allergic reaction.