Conjunctivitis, also called pink eye, is inflammation of the thin clear tissue (conjunctiva) that lies over the white part of the eye (sclera) and lines the underside of the eyelid. It can be caused by bacterial or viral infection, or as a reaction to irritants or allergens entering the eye. Typical symptoms are redness, grittiness, and discharge. Treatment depends on the cause.
Conjunctivitis can occur in people of all ages. However, infectious conjunctivitis is more common in children than in adults, as bacteria and viruses are easily spread from child to child when they play.
In babies, conjunctivitis is often the result of a partially open or blocked tear duct. Neonatal conjunctivitis (occurring during the first three weeks of a baby’s life) can be caused by infection contracted during birth.
Bacterial and viral conjunctivitis often occur at the same time as a cold or other infection of the airways, such as strep throat or sinusitis. Bacterial conjunctivitis can also be caused by wearing contact lenses that have not been cleaned properly.
Because bacterial and viral conjunctivitis are highly contagious, early diagnosis and treatment is important to avoid infecting other people.
Non-infectious conjunctivitis is caused by allergens, chemicals, or environmental factors. The most frequent causes of allergic conjunctivitis are seasonal pollens, animal dander, and dust. Conjunctivitis occurring during pollen season is likely to be a form of hay fever.
Environmental or chemical forms of conjunctivitis are caused by irritating substances entering the eyes. Common irritants are household cleaners, sprays of any kind, smoke, foreign objects, smog, and industrial pollutants.
Symptoms and diagnosis
Diagnosis of conjunctivitis is made by a doctor based on the signs and symptoms and a person's recent health history. Laboratory tests are rarely necessary. Symptoms of conjunctivitis vary depending on the cause.
The symptoms of viral conjunctivitis are variable but usually feature an intensely red eye and excessive watery discharge that is not green or yellow. Viral cold-like symptoms, such as nasal congestion and runny nose, may also be present. The eyelids may be swollen and the eyes sensitive to bright light.
Typical symptoms of bacterial conjunctivitis are thick mucus-like discharge from the eyes, eyelids stuck together in the morning, and swelling of the eyelids . The discharge is usually thick and yellow or green in colour. The lymph nodes located in front of the ears may be enlarged.
The symptoms of allergic conjunctivitis are usually seasonal and include intense itching (made worse by rubbing the eyes) and tearing. Soreness is minimal or absent. These symptoms may be accompanied by other typical allergic symptoms, such as sneezing, itchy nose, and/or a scratchy throat.
Pain, sensitivity to bright lights, watering, and blurred vision are typical symptoms of chemical or environmental conjunctivitis.
Conjunctivitis may be confused with blepharitis, which is inflammation of the edges of the eyelids. Blepharitis is a common eye disorder that affects people of all ages. The typical symptoms are red, itchy, irritated eyelids, and dandruff-like scales on the eyelashes.
You should see your doctor if you think you have conjunctivitis, you have pain inside your eye, there is a sudden change in your vision, or if light makes your eyes hurt.
Babies with symptoms of conjunctivitis should be taken to the doctor immediately because bacterial conjunctivitis can be serious and is highly contagious for others coming in contact with the baby.
If you wear contact lenses and develop symptoms of conjunctivitis, you should stop wearing your lenses and visit your doctor as soon as possible. Conjunctivitis requires prompt treatment if you are a contact lens wearer because it carries a higher risk of keratitis (inflammation of the cornea), which can cause permanent damage to the eyes.
The choice of conjunctivitis treatment largely depends on the cause of the condition.
Viral conjunctivitis will usually disappear on its own (within two to four weeks) without use of anti-viral medication. Symptoms may be relieved by the application of cold compresses and eye drop lubricants, such as artificial tears. However, because viral conjunctivitis is highly contagious for two weeks after symptoms first appear, as long as the eyes are red, it is important to take steps to prevent its spread to other people.
In cases of bacterial conjunctivitis, frequent use of a clean, warm washcloth to remove the discharge may be required. Antibiotic eye drops or ointment prescribed by a doctor may be needed to help clear up the infection. Oral antibiotics may be required for treatment of some infections. With treatment, bacterial conjunctivitis usually resolves within one to two weeks.
For treatment of allergic conjunctivitis, the allergen causing the conjunctivitis should be avoided, as well as the use of eye make-up.
The application of cold, moist washcloths to the eyes and use of lubricating eye drops (not containing preservatives) may provide some relief from the symptoms of allergic conjunctivitis. Decongestant eye drops and antihistamine medication may be obtained from a pharmacy. Stronger medication, such as topical corticosteroids, requires a prescription from your doctor.
Treatment of environmental or chemical conjunctivitis requires prompt and thorough flushing of the eyes with large amounts of water. A healthcare professional should be contacted if a chemical of any type splashes into the eyes. Many common household cleaning products are damaging to delicate eye tissue.
Infectious forms of conjunctivitis are highly contagious, being spread by direct contact with infected people for up to two weeks after their symptoms first appear (i.e., for as long as their eyes are red). Maintaining good personal and household hygiene is the key to preventing the spread of infectious conjunctivitis:
- Avoid contact with people who have conjunctivitis
- Disinfect household surfaces, e.g. doorknobs and countertops
- Avoid touching or rubbing your eyes
- Wash your pillowcases often
- Wash your hands often, using disposable paper towels for drying your hands
- Ensure that eye drops and ointments, facecloths, towels, and pillowcases are not shared
- Do not share eye cosmetics, such as mascara, or contact lenses
- Use and care for your contact lenses correctly
Additionally, children should not attend childcare centres or school when they have signs of conjunctivitis.
Ministry of Health (2020). Conjunctivitis (eye infection or allergic irritation) (Web Page). Wellington: New Zealand Government Ministry of Health. https://www.health.govt.nz/your-health/conditions-and-treatments/diseases-and-illnesses/conjunctivitis-eye-infection-or-allergic-irritation [Accessed 07/02/21]
O’Toole, M.T. (Ed.) (2017). Conjunctivitis. Mosby’s Dictionary of Medicine, Nursing & Health Professions (10th ed.). St Louis, MI: Elsevier.
O’Toole, M.T. (Ed.) (2017). Conjunctivitis of the new born. Mosby’s Dictionary of Medicine, Nursing & Health Professions (10th ed.). St Louis, MI: Elsevier.
Scott, I.U. (2020). Viral Conjunctivitis (pink eye) (Web Page). Medscape Drugs and Diseases. New York, NY: WebMD LLC. https://emedicine.medscape.com/article/1191370-overview [Accessed 07/02/21]
Ventocilla M. (2019). Allergic conjunctivitis (Web Page). Medscape Drugs and Diseases. New York, NY: WebMD LLC. https://emedicine.medscape.com/article/1191467-overview [07/02/21]
Yeung, K.K. (2019). Bacterial conjunctivitis (pink eye) (Web Page). Medscape Drugs and Diseases. New York, NY: WebMD LLC. https://emedicine.medscape.com/article/1191730-overview [Accessed 07/02/21]
Reviewed: February 2021
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