Bacterial Keratitis Clinical Presentation

Updated: May 03, 2017
  • Author: Jean Deschênes, MD, FRCSC; Chief Editor: Hampton Roy, Sr, MD  more...
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Presentation

History

Patients with bacterial keratitis usually complain of rapid onset of pain, photophobia, and decreased vision. It is important to document a complete systemic and ocular history in these patients to identify any potential risk factors that would have made them susceptible to develop this infection, including the following:

  • Contact lens wear (Note the type of lens, wearing time, and type of disinfection system.)
  • Trauma (including previous corneal surgery)
  • Use of contaminated ocular medications
  • Decreased immunologic defenses
  • Use of immunosuppressive agents such as steroid drops that may predispose to infection
  • Aqueous tear deficiencies
  • Recent corneal disease (herpetic keratitis, neurotrophic keratopathy)
  • Structural alteration or malposition of the eyelids
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Physical

External and biomicroscopic examination of these patients reveals some or all of the following features:

  • Ulceration of the epithelium; corneal infiltrate with no significant tissue loss; dense, suppurative stromal inflammation with indistinct edges; stromal tissue loss; and surrounding stromal edema
  • Anterior chamber reaction (cells and flare) with or without hypopyon
  • Folds in the Descemet membrane
  • Upper eyelid edema
  • Posterior synechiae
  • Surrounding corneal inflammation that is either focal or diffuse
  • Conjunctival hyperemia
  • Adherent mucopurulent exudate
  • Endothelial inflammatory plaque
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Causes

Any factor or agent that creates a breakdown of the corneal epithelium is a potential cause or risk factor for bacterial keratitis. Furthermore, exposure to some virulent bacteria that may penetrate intact epithelium (eg, Neisseria gonorrhoeae) also may result in bacterial keratitis.

  • By far the most common cause of trauma to the corneal epithelium and the main risk factor for bacterial keratitis is the use of contact lenses, particularly extended-wear contact lenses. Of patients with bacterial keratitis, 19-42% are contact lens wearers. Incidence of bacterial keratitis secondary to use of extended-wear contact lenses is about 8,000 cases per year. The annual incidence of bacterial keratitis with daily-wear lenses is 3 cases per 10,000.
  • Contaminated ocular medications, contact lens solutions, or contact lens cases [1]
  • Decreased immunologic defenses secondary to malnutrition, alcoholism, and diabetes ( Moraxella)
  • Aqueous tear deficiencies
  • Recent corneal disease (including herpetic keratitis and secondary neurotrophic keratopathy)
  • Structural alteration or malposition of the eyelids (including entropion with trichiasis and lagophthalmos)
  • Chronic dacryocystitis
  • Use of topical corticosteroids
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Physical Examination

A thorough anterior-segment slit-lamp examination in patients with suspected or confirmed bacterial keratitis is essential and should include the following:

  • Best corrected visual acuity
  • Examination for epithelial defects (seen with fluorescein)
  • Examination for corneal infiltrates (whitish opacities in the cornea)
  • Examination for other corneal findings such as thinning or corneal edema
  • Seidel examination for leak of aqueous humor through a perforated area of cornea, if suspicious
  • Anterior chamber examination for cells, flare, and hypopyon
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