An inflammatory process of the conjunctiva, the membrane covering the eye and inside of the eyelids, manifested by erythema and edema, frequently with tearing and discharge. Also known as “pink eye.” There is a wide range in severity and many potential causes. It is critical to rule out gonococcus and herpes simplex virus (HSV) infection because of the destructive nature of the eye disease and potential for vision loss.


  • Children: Viral infection is the most common cause and is highly contagious.
  • Neonates: Ophthalmia neonatorum, conjunctivitis in the 1st month of life, is the most common infection in neonates. Remains a significant cause of blindness in children worldwide. Chlamydia trachomatis is the most common infectious cause.


  • Results from bacterial, viral, allergic, or toxic activation of the inflammatory response that causes dilation and exudation from conjunctival blood vessels
  • Pathology involves dilated conjunctival capillaries with leukocytic infiltration and edema of conjunctiva and substantia propria.


  • Ophthalmia neonatorum
    • If present in the first 24 hours of life, most likely due to chemical irritation from silver nitrate or povidone-iodine (e.g., Wokadine, Betadine) eye drops
    • Gonococcal conjunctivitis is treatable if recognized early but devastating if diagnosis is delayed or missed.
    • Chronic Chlamydia infection can lead to scarring and corneal opacity. Chlamydial pneumonia develops in 20% of patients with chlamydial conjunctivitis.
  • Bacterial
    • Agents include staphylococci, streptococci, Haemophilus, Moraxella, and Pseudomonas.
    • Serious complications of these are rare.
  • Viral
    • Adenovirus is the most common agent.
    • Recurrent HSV infection can lead to significant visual loss from corneal scarring, even with proper therapy.
    • Other viral etiologies usually follow a benign course but rarely can lead to conjunctival scarring.
  • Allergic
    • IgE-mediated hypersensitivity response

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