What causes conjunctivitis?

We know conjunctivitis is caused by the eye’s exposure to bacteria and viruses, but there can still be other factors that contribute to your pink eye. In addition to infection from bacteria, viruses or other organisms, conjunctivitis can be caused by inflammation or allergies.

Here are some causes of conjunctivitis:

  1. Allergic conjunctivitis: This form of conjunctivitis affects people who are prone to developing seasonal allergies. When people come into contact with substances such as pollen, dust particles, and other air irritants, their allergic reaction is triggered which can cause the swelling of their conjunctiva.
  2. Giant papillary conjunctivitis: This type of pink eye can occur when rigid or soft contact lenses enter the eye, thus exposing the eye’s surface to an unnatural material. Prolonged periods of time wearing contact lenses can cause irritation. If contact lenses are not cleaned properly or changed as advised you could end up with conjunctivitis due to the build-up of bacteria.
  3. Bacterial conjunctivitis: Staphylococcal or streptococcal bacteria are usually responsible for infecting the respiratory system and the surface of the eyes. These bacteria are commonly found when making physical contact with other people such as handshakes, or when poor eye hygiene practices are in place. Using contaminated or expired eye make-up can also be a cause of conjunctivitis. Bacterial conjunctivitis is more likely to cause redness of the eye, accompanied by a sticky yellow discharge.
  4. Viral conjunctivitis: As the name suggests, this type of conjunctivitis can occur due to the presence of viruses, which are common with colds and flu. When a person’s respiratory system is exposed to a viral infection, the virus is bound to creep up to other parts of the body, including the eyes. Usually lasting between two and three weeks, viral conjunctivitis may cause a watery red eye. Generally, conjunctivitis does not affect your vision; however, you may experience blurred vision or glare when looking at lights.


Conjunctivitis symptoms

What are the symptoms of conjunctivitis?

The symptoms of conjunctivitis can vary, based on the primary cause. However, pink, bloodshot or puffy eyes are a common indication you may have the condition. Other indicators can include itching, a burning feeling in the eye or sticky eyelashes, particularly when you wake in the morning.

Symptoms you might experience with conjunctivitis:

  • Excessive production of tears
  • A burning and itchy sensation felt in the eye, which leads to the eye producing a thick mucus-like discharge
  • Swollen lymph nodes in the jaw, eyelids, and front of the ear
  • One or both eyes turning pink in colour due to irritation
  • Heightened sensitivity to light
  • Upper respiratory infection or cold
  • Slightly hazy vision


Types of conjunctivitis

  1. Bacterial strains: With bacterial conjunctivitis, either one eye or both eyes are affected. When this type is present, your eye may secrete an excessive amount of pus and mucus as a defence mechanism against additional bacteria entering the eye's surface.
  2. Viral strains: The most common type of conjunctivitis is the viral kind, and it is also the most contagious. With viral conjunctivitis, the virus enters one eye at first and then moves to the other in a few days. A lot of tears are discharged in this type of viral infection and the lymph nodes in your jaw and ear may also swell and become infected.
  3. Ophthalmia neonatorum: This type is prevalent in newborns and is caused by dangerous bacteria that they are exposed to right after delivery.

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