Conjunctivitis is swelling and irritation in the eye. It affects the tissue that covers the eye and lines the inner surface of the eyelid. This tissue is called conjunctiva.

Eye with Conjunctivitis
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There are many causes of conjunctivitis including:

  • Viral infection
  • Bacterial infection, such as staphylococcus or streptococcus
  • Allergic reaction, usually related to seasonal allergies
  • Chemical irritation caused by:
    • Air pollutants
    • Soap
    • Smoke
    • Chlorine
    • Make-up
    • Other chemicals

Both viral and bacterial conjunctivitis are highly contagious.