Eye

Cornea

Infectious keratitis



Topic Completed: 1 October 2013

Minor changes: 21 April 2021

Copyright: 2004-2021, PathologyOutlines.com, Inc.

PubMed Search: Infectious keratitis keratoconjunctivitis pathology

Nat Pernick, M.D.
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Cite this page: Pernick N. Infectious keratitis. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/eyecorneainfectiouskeratitis.html. Accessed December 6th, 2021.
Definition / general
  • Contact lens wearers are susceptible to Pseudomonas and Acanthamoeba
  • Keratitis caused by microfilaria of Onchocerca volvulus is the leading cause of blindness worldwide, outside US
Granulomatous keratitis
  • Due to HSV1, juvenile xanthogranuloma, leprosy, sarcoidosis
Herpes keratitis
  • Most common cause of corneal ulcers
  • Usually unilateral, may recur
  • Usually HSV1
  • Diagnosis difficult in recurrent cases; may need EM, PCR, ISH or immunohistochemistry since cultures are usually negative and inclusions are rarely identified
Microscopic (histologic) description
  • Similar histologic findings for all organisms
  • Destruction of corneal epithelium, Bowman layer and stroma
  • Necrosis and prominent neutrophils
  • Discontinuities of Descemet membrane with corneal perforation
  • Crystal-like stromal opacities with Streptococcus viridans
  • May need special stains to detect organisms

Herpes keratitis:
  • Diffuse epithelial edema causing bullae between epithelium and Bowman layer
  • Also patchy loss of Bowman layer
  • Irregular epithelium
  • Infiltration of anterior stroma by lymphocytes and plasma cells with stromal fibrosis and neovascularization
  • Severe cases have granulomatous reaction surrounding Descemet membrane
  • Herpetic inclusions are rare
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