Conjunctivitis – Causes, Risk Factors and Treatment.


Conjunctivitis is a nonspecific term used to describe an inflammation of the conjunctiva, which can be caused by a wide range of conditions. It is commonly referred to as “red eye” or “pink eye.” Conjunctivitis may result from primary involvement of the conjunctival tissue or may occur secondary to other ocular or systemic conditions that produce conjunctival inflammation.

Conjunctivitis in adults and 7 days old baby

It happens when the conjunctiva is irritated by an infection or allergies. Your eyes are red and swollen (inflamed), and sometimes they have a sticky discharge. You can have conjunctivitis in one or both eyes. Some types of pink eye are very contagious (easily spread from person to person).

In neonates, conjunctivitis is predominantly bacterial, and the most common organism is Chlamydia trachomatis. Chlamydial conjunctivitis typically presents with purulent unilateral or bilateral discharge about a week after birth in children born to mothers who have cervical chlamydial infection.

Types of conjunctivitis

Viral conjunctivitis is the most common type of pink eye. It is caused by the same virus that causes the common cold. This conjunctivitis is very contagious and often spreads through schools and other crowded places. It usually causes burning, red eyes with a watery discharge.


Bacterial conjunctivitis is also very contagious. An infection from bacteria causes this form of pink eye. With bacterial conjunctivitis, you have sore, red eyes with a lot of sticky pus.

Allergic conjunctivitis is a type of pink eye that comes from an allergic reaction to something. It is not contagious. Allergic pink eye makes your eyes very itchy, red and watery.


Viral conjunctivitis is a common ocular disease in the United States and worldwide. Because it is so common, and because many cases are not brought to medical attention, accurate statistics on the frequency of the disease are unavailable. Viral infection frequently occurs in epidemics within families, schools, offices, shipyards, athletic teams, residential communities, and military organizations.


  • Robert Koch and John Elmer discovered conjunctivitis
  • Robert Koch first discovered 2 different types of the conjunctivitis virus in 1883
  • John Weeks discovered the same virus caused pink eye in 1886.
  • The conjunctivitis bacteria is called the Koch Weeks bacillus.
  • The virus was confirmed when Weeks successfully put the virus on his own eye, proving it.

Causes of conjunctivitis

Causes of conjunctivitis include:

  • Bacterial or viral infection
  • Infection with a virus that may also cause a fever and sore throat
  • Sexually transmitted infections (STIs), including chlamydia and gonorrhoea
  • Irritants such as chlorine from swimming pools, shampoo, smoke, fumes or a loose eyelash
  • Seasonal allergic conjunctivitis and perennial (all year round) allergic conjunctivitis, caused by pollen, dust mites or pet dander
  • Contact dermatoconjunctivitis, from eye drops, chemicals or make-up
  • Giant papillary conjunctivitis, from wearing contact lenses, eye surgery stitches or any tubes or things fitted during eye operations.

Risk groups

You may be more at risk of getting infective conjunctivitis if:

  • You’re old or young –it’s more common in children and the elderly, possibly because children come into contact with more infections at school, and elderly people may have a weaker immune system
  • You’ve recently had an upper respiratory tract infection –such as a cold.
  • You have diabetes or another condition that weakens your immune system –as you may be more vulnerable to infections
  • You’re taking corticosteroids (steroids) –which can weaken your immune system
  • You have blepharitis (inflammation of the rims of the eyelids) –which can be caused by a bacterial infection and may lead to conjunctivitis
  • You’ve been in a crowded place – such as a busy train

Symptoms of conjunctivitis can include    

  • Pink or red color in the white of the eye(s) (often one eye for bacterial and often both eyes for viral or allergic conjunctivitis)
  • Swelling of the conjunctiva (the thin layer that lines the white part of the eye and the inside of the eyelid) and/or eyelids
  • Increased tearing
  • Discharge of pus, especially yellow-green (more common in bacterial conjunctivitis)
  • Itching, irritation, and/or burning
  • Feeling like a foreign body is in the eye(s) or an urge to rub the eye(s)
  • Crusting of eyelids or lashes sometimes occurs, especially in the morning
  • Symptoms of a cold, flu, or other respiratory infection may also be present
  • Sensitivity to bright light sometimes occurs
  • Enlargement and/or tenderness, in some cases, of the lymph node in front of the ear. This enlargement may feel like a small lump when touched. (Lymph nodes act as filters in the body, collecting and destroying viruses and bacteria.)
  • Symptoms of allergy, such as an itchy nose, sneezing, a scratchy throat, or asthma may be present in cases of allergic conjunctivitis
  • Contact lenses that do not stay in place on the eye and/or feel uncomfortable due to bumps that may form under the eyelid

Possible complications include

  • Meningitis – an infection of the meninges (the protective layer of cells surrounding the brain and spinal cord)
  • Cellulitis – an infection of the deep layer of skin and tissue that causes the skin on the surface to become sore and inflamed. It’s usually easily treated with antibiotics
  • Septicemia – more commonly known as blood poisoning, septicemia occurs when bacteria get into the bloodstream and attack the body’s tissues
  • Otitis media – a short-term ear infection that affects around one in four children who have had infective conjunctivitis caused by the hemophilic influenza bacteria

Diagnosis and Testing

Often, your ophthalmologist can diagnose conjunctivitis simply by examining your eye. Based on your symptoms, he or she can usually determine whether the inflammation is due to a viral or bacterial infection. He or she may perform the following tests to confirm a diagnosis:

Medical History

Your ophthalmologist can rule out many causes of conjunctivitis simply by asking about your symptoms and how they came about. He or she also asks whether you’ve been in close contact with other people who have conjunctivitis and if any irritant has come into contact with your eye.

Slit Lamp Exam

Most of the time, your doctor can diagnose conjunctivitis by using a slit lamp—an instrument that consists of a microscope and a high-energy beam of light. During a slit-lamp exam, your ophthalmologist shines a thin beam of light into your eye. This beam allows your doctor to examine the entire eye, including the conjunctiva; the sclera, or the white of the eye; the iris; and the cornea.


For a more detailed look at the eye, your doctor may put a drop of a yellow dye called fluorescein into your eye, which allows him or her to see any damage to the surface of the eye.

Visual Acuity Tests

Doctors also check to see if conjunctivitis has affected your vision by conducting a visual acuity test. This test checks to see how well you can read letters or symbols from 20 feet away, while covering one eye at a time.


Snellen chart for visual acuity test

Eye Culture

If you have had conjunctivitis for more than two or three weeks and it has not gone away on its own or with the help of home treatments, your doctor may want to perform an eye culture. During this test, your doctor takes a sample of the cells on the inside of your eyelids with a cotton swab and sends it to a laboratory to be examined by a pathologist.

A pathologist, who studies diseases under a microscope, can determine whether your conjunctivitis is caused by viruses or bacteria. This helps your doctor determine the most effective treatment.

Treatments and medications for Conjunctivitis


  • To relieve the discomfort associated with viral, bacterial, or allergic conjunctivitis, your ophthalmologist may recommend applying either a warm or cold compress a moist washcloth or hand towel—to your closed eyelids three or four times a day.
  • Warm compresses help to reduce the sticky buildup of discharge on the eyelids or crust that forms on your eyelashes, while cold compresses help to relieve itching and inflammation.

Avoid Contact Lenses

  • If you’ve been diagnosed with viral or bacterial conjunctivitis, your doctor may recommend removing contact lenses and wearing glasses instead for 10 to 12 days, or until the condition has gone away.
  • Rarely, previously worn contact lenses may be a source of reinfection. For this reason, your doctor may ask you to carefully disinfect or discard those lenses and even their cases.
  • For some people, eye makeup may be a source of contamination and reinfection, so your doctor may recommend that you discard certain products.

Rinse Your Eye

  • When you’re exposed to allergens, your body releases a chemical called histamine, causing redness, tears, and itching in the eye.
  • For conjunctivitis caused by a mild irritant, like shampoo or perfume spray, sometimes rinsing the eye with cold or lukewarm water for at least five minutes can help relieve the discomfort.

Avoid Triggers

If you know what triggers symptoms of conjunctivitis, avoid them if possible. If you are prone to allergic conjunctivitis, for instance, limit the amount of time you spend outside when pollen or ragweed levels are high, or take allergy medications that can help prevent symptoms.

Keeping the windows and doors closed during seasons with high pollen counts can prevent allergens from entering your home. Try not to let dust gather at home, and treat any mold.


Artificial Tears

  • To relieve the dryness associated with viral, bacterial, and allergic conjunctivitis, or conjunctivitis caused by chemical irritation, your doctor may recommend artificial tears, an over-the-counter medication that lubricates the eye. Artificial tears also help eliminate allergens that cause conjunctivitis.
  • Your doctor may recommend you use drops in both eyes, two to four times a day. If you only have conjunctivitis in one eye, you should not use the same drops in the unaffected eye, or you risk spreading the condition.


For bacterial conjunctivitis, your doctor may recommend antibiotics in the form of eye drops. They are typically used three to four times a day for five to seven days. The dosage depends on your condition and the type of antibiotics your doctor prescribes.


This class of medications is beneficial for allergic conjunctivitis. Administered topically twice a day or taken once a day by mouth, antihistamines block the action of histamine, a chemical that is produced when the body detects an allergen, such as pollen, dust, mold, or pet dander.

This helps prevent inflammation, itching, and discomfort. Antihistamines are generally well tolerated but may contribute to dry eye.

Anti-inflammatory Drugs

Nonsteroidal anti-inflammatory drugs, also known as NSAIDs, reduce inflammation and redness, as well as itching. They are available as eye drops, and your doctor may recommend that you use the drops several times a day. When applied, they may cause a burning sensation, but it usually subsides over time.

Topical Corticosteroids

For severe conjunctivitis, which often results from a chemical injury, doctors may prescribe topical corticosteroids as a short-term treatment. Corticosteroids can reduce inflammation in the eye. Although they are effective, there can be serious side effects, including blurred vision, increased pressure in the eye, and cataracts. Therefore, your doctor may recommend that you use these medications for only a couple of weeks.

Mast-Cell Stabilizers

  • This type of medication, which is available as eye drops, targets allergic conjunctivitis by preventing the body from releasing histamine during an allergic reaction. Mast-cell stabilizers are intended for preventive use rather than immediate relief and may take up to two weeks to begin working.
  • They can be effective in people with seasonal allergic conjunctivitis or those who have an allergic reaction to contact lenses.

Preventing the Spread of Conjunctivitis

Conjunctivitis caused by allergens is not contagious; however, viral and bacterial conjunctivitis can be easily spread from person to person and can cause epidemics. You can greatly reduce the risk of getting conjunctivitis or of passing it on to someone else by following some simple good hygiene steps.

If you have infectious (viral or bacterial) conjunctivitis, you can help limit its spread to other people by following these steps:

  • Wash your hands often with soap and warm water. If soap and water are not available, use an alcohol-based hand sanitizer that contains at least 60% alcohol.
  • Avoid touching or rubbing your eyes.
  • Wash any discharge from around the eyes several times a day. Hands should be washed first and then a clean washcloth or fresh cotton ball or tissue can be used to cleanse the eye area. Throw away cotton balls or tissues after use; if a washcloth is used, it should be washed with hot water and detergent. Wash your hands with soap and warm water when done.
  • Wash hands after applying eye drops or ointment.
  • Do not use the same eye drop dispenser/bottle for infected and non-infected eyes—even for the same person.
  • Wash pillowcases, sheets, washcloths, and towels in hot water and detergent; hands should be washed after handling such items.
  • Avoid sharing articles like towels, blankets, and pillowcases.
  • Clean eyeglasses, being careful not to contaminate items (like towels) that might be shared by other people.
  • Do not share eye makeup, face make-up, make-up brushes, contact lenses and containers, or eyeglasses.
  • Do not use swimming pools.

If you are around someone with infectious (viral or bacterial) conjunctivitis, you can reduce your risk of infection by following these steps:

  • Wash your hands often with soap and warm water. If soap and warm water are not available, use an alcohol-based hand rub.
  • Wash your hands after contact with an infected person or items he or she uses; for example, wash your hands after applying eye drops or ointment to an infected person’s eye(s) or after putting their bed linens in the washing machine.
  • Avoid touching or rubbing your eyes.
  • Do not share items used by an infected person; for example, do not share pillows, washcloths, towels, eye drops, eye or face makeup, and eyeglasses.
  • Clean, store, and replace your contact lenses as instructed by your eye doctor.

In addition, if you have infectious conjunctivitis, there are steps you can take to avoid reinfection once the infection goes away:

  • Throw away and replace any eye or face makeup you used while infected.
  • Throw away contact lens solutions that you used while your eyes were infected.
  • Throw away disposable contact lenses and cases that were used while your eyes were infected.
  • Clean extended wear lenses as directed.
  • Clean eyeglasses and cases that were used while infected.

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  1. Thankyou very much for your article on pink eye. i have had it seasonally for 50 years and never knew it.
    God bless you all much!

  2. thank you for your information about types of conjunctivitis
    i hope this application be more prevalent and more useful

  3. ChristianYour Name

    Nice one. Thanks.

  4. Am glad I come across this this information. Am down with the bacteria and the info has been a huge help. Knowledge is power.

  5. pls I need a specific name of eye drop to use because I’ve tried different medications to no avail

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