6 Causes Of Pink Eye (Conjunctivitis)

what causes pink eye

Itchy, crusty, red eyes that water. Sound familiar? These symptoms point to an inflammation of the tissue that covers your eyes in the front called the conjunctiva. Conjunctivitis or pink eye is a common condition and we’ve all suffered from it at some point or the other. But have you ever wondered what causes conjunctivitis?

A variety of causes can be responsible for the pink eye.

1. Viruses

Viral conjunctivitis is extremely contagious. This infection is usually caused by adenoviruses which cause colds and, sometimes, by enteroviruses which also cause respiratory infections. Other viruses which cause diseases like mumps, measles, chickenpox, herpes, and rubella can also cause conjunctivitis.

Viral conjunctivitis is usually spread by contaminated hands touching your eyes. And how does this happen? Your hands can get contaminated by coming in contact with eye discharge, tears, respiratory discharges, or fecal matter that has been infected. You can also get viral conjunctivitis through respiratory droplets through coughing, sneezing etc.; or if your eyes come in contact with a contaminated object like a towel or tissue. Also, the viruses that cause herpes can be

passed on from a mother to her baby during the process of childbirth and cause significant eye damage in the infant.1 2

2. Bacteria

Bacterial conjunctivitis is also highly contagious. It’s usually spread by contaminated hands touching the eyes. You can catch bacterial conjunctivitis by touching or using something that an infected person has used and through respiratory droplets. Children and toddlers are especially vulnerable to getting pink eye from viruses and bacteria as they come into contact with other infected children with conjunctivitis in school or day care. Hygiene practices are also difficult to impose at this age.

The bacteria that usually cause this kind of conjunctivitis in the United States include Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus influenza, and Moraxella catarrhalis.

Some kinds of bacterial conjunctivitis require particular attention:

  • Neisseria gonorrhoeae, the bacteria that cause gonorrhea, can trigger a severe kind of conjunctivitis which
    tends to develop suddenly and where you see a yellowish green discharge from the eyes. This kind of conjunctivitis is spread through sexual contact when the eyes come in touch with genital secretions from a person who has gonorrhea. This infection may cause vision loss and requires prompt medical attention.
  • Chlamydia trachomatis, the bacteria that causes chlamydia, can also lead to chronic conjunctivitis. They spread through sexual contact if you come in contact with genital secretions from an infected person. Chlamydia trachomatis also cause a kind of conjunctivitis called trachoma, where you see scarring of the conjunctiva and cornea. It is the most common cause of preventable infectious blindness globally. Trachoma can be transmitted by sharing contaminated items with an infected person as well as through flies which sit on your eyes after sitting on an infected person’s eyes.

Both chlamydia and gonorrhea can cause conjunctivitis in a newborn if it’s passed on by an infected mother during the process of childbirth. These infections can result in lasting eye damage in a baby and need immediate medical attention.3

3. Fungi

Though it’s rare, sometimes fungi can also cause conjunctivitis. These are usually seen in people who experience an eye injury that involves the eyes coming in contact with organic matter like dirt or plants. People who use corticosteroid eye drops for long periods of time may also get this infection.4

4. Allergens

Your body’s reaction to substances that it is allergic can result in conjunctivitis. Allergic conjunctivitis is common in people who have other allergic diseases like asthma, eczema, and hay fever. This may be seasonal in nature if it’s caused by things like pollen, weeds, grass etc. which may occur seasonally. It can be perennial if it’s caused by things like animal dander or dust mites which tend to be present throughout the year.

5. Irritants

Substances that irritate your conjunctiva can cause conjunctivitis too. This may include a foreign object in your eye, smoke, dust, wind,

bright ultraviolet light, chlorine etc. People who constantly have a foreign object like contact lenses in their eyes can also develop conjunctivitis as a reaction to these.

6. Eye Conditions

Some eye conditions are also associated with conjunctivitis:

  • Conditions which cause the eyelid to turn inward (entropion) or outward (ectropion) can cause irritation resulting in conjunctivitis.
  • Blepharitis, a condition where the eyelids get inflamed is also associated with conjunctivitis. Bacterial growth and flaky debris along the eyelid can also be observed during this condition.
  • Chronic dacryocystitis, which is an infection that occurs in the tear sac, is also linked to conjunctivitis.5 6

How Do You Deal With Conjunctivitis?

Treatment for conjunctivitis will depend on its cause. Antibiotics may be prescribed for cases caused by bacteria while viral cases may resolve on their own. Meanwhile, avoiding exposure to an allergen or irritant can deal with conjunctivitis caused by

these. Do seek medical attention if your symptoms continue for more than 3 or 4 days or the condition impacts your vision. It’s also a good idea to get in touch with your doctor if your eyelids or the skin around your eyes seem inflamed, you’re experiencing severe or worsening eye pain, or have a headache.7