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Contact lens - related microbial keratitis (CLRMK)

Last reviewed dd mmm yyyy. Last edited dd mmm yyyy

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Contact lens-related microbial keratitis (CLRMK)

  • infection and inflammation of the cornea associated with microbial contamination of lenses (1,2)
  • most important risk factors
    • soft contact lens wear
      • overnight wearing
      • daily wear lenses - not to be worn while sleeping
      • higher incidence of keratitis in wearers who sleep in contact lenses (3)
      • to sleep in lenses
        • silicone hydrogel lenses, carries a five times decreased risk of keratitis compared with hydrogel lenses (3)
    • extended wear
      • greater risk of corneal infection

23–94% of contact lens wearers report associated discomfort and eye problems. The annual incidence of contact lens–associated keratitis is 2–4/10 000. It is due to bacteria in 90% of cases, and much less commonly to acanthamoebae and fungi (10)

Common organisms:

  • bacterial
    • Pseudomonas aeruginosa (commonest). Klebsiella pneumoniae may also cause microbial keratitis
    • identified by occurrence of a larger infiltrate (4)
      • produces proteases
        • invade
        • destroy corneal cells
      • excessive activation of the host defense system
        • involving receptors on the corneal epithelial cells called toll-like receptors (TLRs)
        • leads to destruction of corneal cells
          • scarring and vision loss
  • amoebic
    • Acanthamoeba
      • Acanthamoeba keratitis (5)
      • identified by observing a ring infiltrate
        • major risk factors
          • failure to disinfect daily wear soft contact lenses
          • use of chlorine release lens disinfection systems (little protective effect against the organism)
            • ineffective at killing Acanthamoeba cysts and trophozoites
          • improvement of contact lens disinfecting systems is needed to prevent Acanthamoeba keratitis (6)
  • fungal
    • caused by fusarium (commonest) Candida , Curvularia, and Aspergillus
    • a serious corneal infection
    • associated with poor contact lens solutions (7)
      • contact lenses are a major risk factor
      • needs aggressive topical antifungal therapy
  • some are Polymicrobial

Management of contact lens-associated corneal infiltrative events (CIEs) (8)

  • lens wear should be suspended
  • contact lens solutions discontinued
  • anti-microbial therapy initiated immediately
  • changes in contact lens wearing schedules, and materials
  • referred to ophthalmologist immediately

Reference:

  1. Preechawatmd P. Contact lens-related microbial keratitis. J Med Assoc Thai. 2007 Apr;90(4):737-43
  2. Willcox MD.Pseudomonas aeruginosa infection and inflammation during contact lens wear: a review. Optom Vis Sci. 2007 Apr;84(4):273-8
  3. Morgan PB et al. Incidence of keratitis of varying severity among contact lens wearers. Br J Ophthalmol. 2005 Apr;89(4):430-6
  4. Dahlgren MA et al. The clinical diagnosis of microbial keratitis.Am J Ophthalmol. 2007 Jun;143(6):940-944
  5. Radford CF et al. Risk factors for acanthamoeba keratitis in contact lens users: a case-control study. BMJ. 1995 Jun 17;310(6994):1567-70.
  6. Tzanetou K et al. Acanthamoeba keratitis and contact lens disinfecting solutions. Ophthalmologica. 2006;220(4):238-41.
  7. Chang DC et al. Multistate outbreak of Fusarium keratitis associated with use of a contact lens solution. JAMA. 2006 Aug 23;296(8):953-63
  8. Efron N, Morgan PB. Rethinking contact lens associated keratitis. Clin Exp Optom. 2006 Sep;89(5):280-98
  9. Suchecki JK et al. Contact lens complications.Ophthalmol Clin North Am. 2003 Sep;16(3):471-84.
  10. Contact Lens–Associated Keratitis— an Often Underestimated Risk - PMC (nih.gov) (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9830382/#:~:text=The%20wearing%20of%20contact%20lenses,contact%20lens%20wearers%20per%20year).)

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