Eye
Cornea
Infectious keratitis
Author: Nat Pernick, M.D.
Last author update: 1 October 2013
Last staff update: 21 April 2021
Copyright: 2004-2025, PathologyOutlines.com, Inc.
PubMed Search: Infectious keratitis keratoconjunctivitis pathology
Table of Contents
Definition / general | Granulomatous keratitis | Herpes keratitis | Microscopic (histologic) descriptionCite this page: Pernick N. Infectious keratitis. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/eyecorneainfectiouskeratitis.html. Accessed April 2nd, 2025.
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
