• Clinical science



Conjunctivitis 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 (“pinkeye”). 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 anti-infective, anti-inflammatory 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).

Clinical features

General signs and symptoms of conjunctivitis

  • Conjunctival hyperemia with dilatation of blood vessels (injection) → “pinkeye”
  • Discharge and crust formation
  • Chemosis
  • Foreign-body sensation
  • Photophobia

Bacterial vs viral conjunctivitis

Bacterial Viral
  • Usually unilateral
  • Thick purulent discharge (yellow, white or green)
  • Reduced vision and risk of blindness (if cornea is involved)
  • Extraocular signs of bacterial infection
  • See additional features of certain causes below
  • Bilateral (usually begins with one eye and spreads to the other within a few days)
  • Clear, watery discharge (with mucoid component) . → Excessive tearing (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, pharyngitis
  • See additional features of certain causes below


Viral conjunctivitis

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


Bacterial conjunctivitis


Neisserial conjunctivitis

Granular conjunctivitis (trachoma)

  • Etiology
    • Infection with Chlamydia trachomatis type A-C
    • Route of infection: direct (human-to-human contact with eyes or nose) or indirect (flies or towels) contact
    • Incubation period: 5–12 days
  • Epidemiology
    • Most common cause of blindness due to chronic scarring worldwide
    • Predominantly affects young children and women
  • Clinical features: see “Clinical features” above
    • Can be divided into two stages which may occur simultaneously
      • Active phase; : conjunctival follicles (with eventual involution), inflamed upper tarsal conjunctiva
      • Cicatricial phase : chronic/recurring inflammation in both eyes → conjunctival scarring → progressive conjunctival shrinkage → corneal ulcers and opacities, neovascularization, entropion, trichiasis
  • Treatment/Prevention
    • Antibiotics
    • Surgical intervention (eyelid correction in trichiasis)
    • Hygienic measures (particularly facial cleanliness) and environmental improvement (e.g., supply of clean water)
  • Prognosis: good (if treated early)

SAFE strategy (WHO) - Surgery, Antibiotics, Facial cleanliness, Environmental improvement

Inclusion conjunctivitis (paratrachoma)


Newborn conjunctivitis

Chemical conjunctivitis Gonococcal conjunctivitis Chlamydial conjunctivitis Viral conjunctivitis
Underlying cause
  • Usually due to silver nitrate exposure
Onset after birth
  • Usually first day
  • 2–7 days
  • 5–14 days
  • Within 14 days
Clinical features
  • Mild conjunctival injections
  • Profuse purulent ocular drainage, pronounced eyelid swelling
  • Watery/mucopurulent ocular discharge, mild eyelid swelling
  • Nonpurulent ocular discharge, corneal ulceration, periocular vesicles
  • Patient history
  • Cultures and gram stain (on blood, chocolate agar, and conjunctival scrapings) or PCR
  • Cultures and gram stain (on blood, chocolate agar, and conjunctival scrapings) or PCR
  • Flush eye with saline
  • Systemic acyclovir plus topical drugs (e.g., vidarabine) for 14–21 days
  • Prenatal maternal screening and systemic antibiotic treatment
  • Proper hygiene

Suspect and treat for gonococcal infection in newborns with conjunctivitis unless proven otherwise!


Non-infectious conjunctivitis

Ocular cicatricial pemphigoid (OCP)

  • Etiology: autoimmune
  • Epidemiology: predominantly affects older women
  • Pathology: subepithelial blistering with subsequent scarring
  • Symptoms/Clinical features
    • Paroxysmal, chronic course, often with unilateral onset
    • General signs and symptoms of conjunctivitis
    • Progressive scarring of the conjunctiva: subepithelial fibrosis → fornix shortening → symblepharon → ankyloblepharon with immobilization of the globe
    • Extraocular features: oral lesions (e.g., gingivitis), skin lesions on head, neck or upper trunk
  • 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)

  • Definition: disease of the eye surface caused by underproduction or changes in the composition of lacrimal fluid or by increased evaporation
  • Epidemiology
    • Very common in the US, especially > 40 years
    • >
  • Etiology
  • Clinical features
  • Diagnosis
  • Treatment
    • Avoid triggers (e.g., dry air) or change environment (e.g., use of humidifiers)
    • Patient education on eyelid hygiene
    • Medical therapy
      • Artificial tears and ocular lubricants
      • If symptoms persist despite above therapy
    • Surgical (if symptoms persist despite above medical therapy)