Written and peer-reviewed by physicians—but use at your own risk. Read our disclaimer.

banner image


Trusted medical answers—in seconds.

Get access to 1,000+ medical articles with instant search
and clinical tools.

Try free for 5 days


Last updated: October 7, 2019


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

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
  • 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



  1. Lorenzo-Morales J, Khan NA, Walochnik J. An update on acanthamoeba keratitis: diagnosis, pathogenesis and treatment. Parasite. 2015; 22 (10). doi: 10.1051/parasite/2015010 . | Open in Read by QxMD
  2. Acanthamoeba Keratitis. https://www.cdc.gov/parasites/acanthamoeba/index.html. Updated: June 5, 2017. Accessed: August 28, 2017.
  3. Albrecht MA, Hirsch MS, Mitty J. Treatment of Herpes Zoster in the Immunocompetent Host. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/treatment-of-herpes-zoster-in-the-immunocompetent-host.Last updated: July 21, 2016. Accessed: December 29, 2016.
  4. Agabegi SS, Agebegi ED. Step-Up to Medicine. Lippincott Williams & Wilkins, Wolters Kluwer Health ; 2015
  5. Bajwa Zh, Ho CC, Khan SA, Garza I, Swanson JW, Dashe JF. Overview of Craniofacial Pain. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/overview-of-craniofacial-pain.Last updated: July 21, 2015. Accessed: April 2, 2017.
  6. Olver J, Cassidy L, Jutley G. Ophthalmology at a Glance. John Wiley & Sons ; 2014
  7. Herpes simplex virus keratitis treatment guideline. https://www.aao.org/clinical-statement/herpes-simplex-virus-keratitis-treatment-guideline. Updated: June 1, 2014. Accessed: August 28, 2017.
  8. Sugar A, Trobe J, Hirsch MS, Libman H. Herpes Simplex Keratitis. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/herpes-simplex-keratitis.Last updated: March 20, 2017. Accessed: August 28, 2017.
  9. Herpes Zoster Ophthalmicus. https://www.aao.org/focalpointssnippetdetail.aspx?id=8367b620-245c-4ebf-89e7-eca0c8d35aa3. . Accessed: August 28, 2017.
  10. Shaik S, Ta CN. Evaluation and management of herpes zoster ophthalmicus. Am Fam Physician. 2002; 66 (9): p.1723-1730.
  11. Eltis M. Contact-lens-related microbial keratitis: case report and review. J Optom. 2011; 4 (4): p.122-127. doi: 10.1016/S1888-4296(11)70053-X . | Open in Read by QxMD
  12. Majmudar PA, Hampton R. Interstitial Keratitis. Interstitial Keratitis. New York, NY: WebMD. http://emedicine.medscape.com/article/1194376. Updated: November 9, 2015. Accessed: August 26, 2017.
  13. Al-Mujaini A, Al-Kharusi N, Thakral A, Wali UK. Bacterial keratitis: Perspective on epidemiology, clinico-pathogenesis, diagnosis and treatment. Sultan Qaboos Univ Med J.. 2009; 9 (2): p.184-195.
  14. Jacobs DS, Trobe J, Libman H. Evaluation of the Red Eye. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/evaluation-of-the-red-eye.Last updated: August 26, 2017. Accessed: August 26, 2017.
  15. Deschênes J, Hampton R. Bacterial Keratitis. Bacterial Keratitis. New York, NY: WebMD. http://emedicine.medscape.com/article/1194028. Updated: May 3, 2017. Accessed: August 26, 2017.
  16. Bacterial Keratitis Preferred Practice Pattern Guideline. https://www.aao.org/preferred-practice-pattern/bacterial-keratitis-ppp--2013#BACKGROUND. Updated: October 1, 2013. Accessed: August 26, 2017.
  17. Nucci M, Anaissie E, Kauffman CA, Thorner AR. Mycology, Pathogenesis, and Epidemiology of Fusarium Infection. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/mycology-pathogenesis-and-epidemiology-of-fusarium-infection.Last updated: June 27, 2017. Accessed: October 7, 2017.
  18. Ansari Z, Miller D, Galor A. Current thoughts in fungal keratitis: Diagnosis and treatment. Curr Fungal Infect Rep. 2013; 7 (3): p.209–218. doi: 10.1007/s12281-013-0150-110.1007/s12281-013-0150-1 . | Open in Read by QxMD
  19. DeLoss KS, Soong K, Hood CT, Trobe J, Libman H. Complications of Contact Lenses. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/complications-of-contact-lenses.Last updated: September 25, 2017. Accessed: October 7, 2017.
  20. Ross M, Deschênes J. Fungal Keratitis. In: Talavera F, Rapuano CJ, Fungal Keratitis. New York, NY: WebMD. http://emedicine.medscape.com/article/1194167. Updated: September 8, 2017. Accessed: October 7, 2017.