Last updated: January 9, 2022

Summarytoggle arrow icon

Conjunctivitis (pink eye) is a very common inflammation of the conjunctiva (the mucus membrane that lines the inside of the eyelids and the sclera). It is most commonly caused by viruses or bacteria but can also have noninfectious (e.g., allergic) causes. It is also commonly associated with corneal inflammation (then referred to as keratoconjunctivitis). Conjunctivitis is the most common cause of ocular hyperemia. Other classic features are burning, foreign body sensation, excessive tearing, and photophobia. Additionally, in infectious conjunctivitis, general signs of viral or bacterial infection (e.g., fever) may be seen, while itching is particularly common in allergic conjunctivitis. Dry eye is a hallmark feature of keratoconjunctivitis sicca. In most cases, local pharmacologic therapy with antiinfective, antiinflammatory and/or antiallergic agents is sufficient. However, bacterial conjunctivitis can lead to blindness in newborns; therefore, strict and rapid treatment and prevention is vital. Surgical intervention is only rarely useful or necessary (e.g., correction of eyelids). An important differential diagnosis of conjunctivitis is subconjunctival hemorrhage, which is a collection of blood between the conjunctiva and the sclera that typically appears as a focal, red region on the surface of the eye.

In adults

Overview of conjunctivitis in adults
Type Gonococcal conjunctivitis Trachoma Nongonococcal bacterial conjunctivitis Viral conjunctivitis Allergic conjunctivitis
  • S. aureus (most common in adults)
  • H. influenzae
Clinical features

In newborns

Overview of conjunctivitis in newborns
Chemical conjunctivitis Neonatal gonococcal conjunctivitis Chlamydial conjunctivitis Viral conjunctivitis
  • Usually due to silver nitrate exposure
Onset after birth
  • Usually first day
  • 2–7 days
  • 5–14 days
  • Within 14 days
Clinical features
  • Watery/mucopurulent ocular discharge, eyelid swelling
  • Nonpurulent ocular discharge, corneal ulceration, periocular vesicles
  • Systemic acyclovir plus topical drugs (e.g., vidarabine) for 14–21 days
  • Prenatal maternal screening and systemic antibiotic treatment
  • Proper hygiene

Gonococcal conjunctivitis is an emergency. Suspect and treat for gonococcal infection in newborns with conjunctivitis unless another cause of infection is found.

Bacterial vs viral conjunctivitis
Bacterial Viral
  • Usually unilateral
  • Bilateral (usually begins with one eye and spreads to the other within a few days)
Ocular discharge
  • Thick purulent discharge (yellow, white or green)
  • Clear, watery discharge (with mucoid component) .
  • Reduced; risk of blindness (if cornea is involved)
  • Usually normal
Additional symptoms
  • Extraocular signs of bacterial infection
  • See additional features of certain causes below.
  • Increased lacrimation (epiphora)
  • Usually normal vision
  • Conjunctival follicles
    • Small raised, yellowish-white hyperplasia of lymphatic tissue, usually with peripheral (rather than central) vascularization
    • Particularly on the palpebral and bulbar conjunctiva
  • Extraocular/general signs of viral infection : e.g., fever, lymphadenopathy (e.g., preauricular node), pharyngitis
  • See additional features of certain causes below.

Patient education regarding proper hygiene is essential to prevent an outbreak!

References: [1][2][3]


Neisserial conjunctivitis

N. gonorrhoeae infection is an ocular emergency that can lead to keratitis, perforation, and blindness without prompt treatment!

Trachoma (granular conjunctivitis)

Chlamydia trachomatis serotypes A, B, and C are most common in Africa and can cause Blindness and Chronic infection.

The WHO introduced the SAFE strategy for trachoma elimination: Surgery, Antibiotics, Facial cleanliness, Environmental improvement.

Inclusion conjunctivitis (paratrachoma)


Ocular cicatricial pemphigoid (OCP)

  • Etiology: autoimmune
  • Epidemiology: predominantly affects older women
  • Pathology: subepithelial blistering with subsequent scarring
  • Symptoms/Clinical features
  • Diagnostics: biopsy → histologic staining (immunofluorescent staining of antibodies)
  • Treatment
  • Prognosis
    • Usually chronic progression (∼ 10–30 years from symptom onset to end stage) with periods of remission and exacerbation
    • Individual progression on or off treatment is unpredictable (long term follow-up is vital)

Allergic conjunctivitis

Keratoconjunctivitis sicca (dry eye disease)


The differential diagnoses listed here are not exhaustive.

  1. Melendez CP, Florentino MM, Martinez IL, Lopez HM. Outbreak of epidemic keratoconjunctivitis caused by adenovirus in medical residents. Mol Vis. 2009; 15 : p.557-562.
  2. Pihos AM. Epidemic keratoconjunctivitis: A review of current concepts in management. J Optom. 2013; 6 (2): p.69-74. doi: 10.1016/j.optom.2012.08.003 . | Open in Read by QxMD
  3. Chintakuntlawar AV, Chodosh J. Cellular and tissue architecture of conjunctival membranes in epidemic keratoconjunctivitis. Ocul Immunol Inflamm. 2010; 18 (5): p.341-345. doi: 10.3109/09273948.2010.498658 . | Open in Read by QxMD
  4. Jin J. Prevention of Gonococcal Eye Infection in Newborns. JAMA. 2019; 321 (4): p.414. doi: 10.1001/jama.2018.21434 . | Open in Read by QxMD
  5. Bourne RRA, Stevens GA, White RA, et al. Causes of vision loss worldwide, 1990–2010: a systematic analysis. The Lancet Global Health. 2013; 1 (6): p.e339-e349. doi: 10.1016/s2214-109x(13)70113-x . | Open in Read by QxMD
  6. Acute Bacterial Conjunctivitis. Updated: September 1, 2016. Accessed: May 17, 2017.
  7. Trachoma. Updated: April 1, 2017. Accessed: May 17, 2017.
  8. Smolin G, Foster CS, Azar DT, Dohlman CH. Smolin and Thoft's The Cornea. Lippincott Williams & Wilkins ; 2005
  9. Superficial Punctate Keratitis. Updated: December 1, 2016. Accessed: May 17, 2017.
  10. Fighting Filamentary Keratitis. Updated: February 15, 2015. Accessed: May 17, 2017.
  11. Kiratli H, Tarlan. Subconjunctival hemorrhage: risk factors and potential indicators. Clinical Ophthalmology. 2013 : p.1163. doi: 10.2147/opth.s35062 . | Open in Read by QxMD

3 free articles remaining

You have 3 free member-only articles left this month. Sign up and get unlimited access.
 Evidence-based content, created and peer-reviewed by physicians. Read the disclaimer