• Clinical science



Keratitis is inflammation of the cornea, a clear and transparent covering over the iris and pupil. Important forms of keratitis include bacterial, herpes zoster, herpes simplex, and Acanthamoeba keratitis. Most corneal injuries and infections are associated with severe pain, although sometimes pain is absent. Other findings include irritation, eye redness, watery or purulent secretion, and impaired vision. Diagnosis is usually based on clinical findings and slit-lamp examination. Keratitis is an emergent disorder that can lead to irreversible vision loss left untreated.


Characteristic features Therapy
Bacterial keratitis
  • Most common form of keratitis
  • ↑ Risk with wearing contact lenses
  • Purulent discharge and/or hypopyon
  • Round corneal infiltrate or ulcer
Herpes zoster keratitis
  • ↓ Corneal sensation
  • Punctate lesions on the corneal surface (early disease)
  • Vesicular eruption on forehead, bridge, and tip of the nose
Herpes simplex keratitis
  • Dendritic or geographic corneal ulcer
Acanthamoeba keratitis
  • ↑ Risk with wearing contact lenses
  • Corneal ring infiltrate

Bacterial keratitis

Bacterial keratitis should be treated as an ophthalmic emergency because of the risk of irreversible vision loss!


Viral keratitis

Herpes simplex keratitis

  • Etiology: infection due to reactivated herpes simplex virus (HSV) type 1 from the trigeminal ganglion
  • Clinical features
    • Similar to viral conjunctivitis, but usually unilateral
    • Eye redness
    • ± Eye pain
    • Foreign body sensation
    • Photophobia
    • Blurry vision; can lead to vision loss if untreated
  • Diagnostics
  • Treatment for epithelial HSV keratitis
    • Topical trifluridine or ganciclovir
    • Oral antiviral (e.g., acyclovir) when topical treatment cannot be administered by the patient, prophylactic treatment after surgery, or refractory cases despite topical treatment
    • Corneal transplantation for patients with severe corneal scarring

Glucocorticoids should not be used in initial treatment of dendritic epithelial keratitis!

Herpes zoster keratitis


See epidemic keratoconjunctivitis.


Acanthamoeba keratitis

  • Etiology: Acanthamoeba infection
  • Characteristics
    • Rare condition
    • Primarily occurs in immunocompetent contact lens wearers
    • Progressive course for several weeks despite an attempt of antibiotic treatment
  • Clinical features
    • Severe pain
    • Eye redness
    • Photophobia
    • Epiphora
    • Decrease in vision
    • Corneal ring infiltrate (late-stage)
  • Diagnostics
    • Slit-lamp examination and/or fluorescein staining: features of epithelitis and stromal disease
    • Culture and microscopy of eye scraping
    • Pathogen detection is often difficult.
  • Treatment