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International multi-center review of Diffuse Lamellar Keratitis Outbreaks: 12-year experience

International multi-center review of Diffuse Lamellar Keratitis Outbreaks: 12-year experience. Simon Holland Doug Morck Yumi Ohashi WCCVI April 2010 authors have no financial interests. Aim: To evaluate strategies for investigation and control of Diffuse Lamellar Keratitis  (DLK) outbreaks.

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International multi-center review of Diffuse Lamellar Keratitis Outbreaks: 12-year experience

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  1. International multi-center review of Diffuse Lamellar Keratitis Outbreaks: 12-year experience Simon Holland Doug Morck Yumi Ohashi WCCVI April 2010 authors have no financial interests

  2. Aim:To evaluate strategies for investigation and control of Diffuse Lamellar Keratitis  (DLK) outbreaks

  3. Methods • Retrospective consecutive series • 62 DLK outbreaks: 8 countries, 1998 – 2009 • Site visits: 27 • Investigations: review of surgical procedures, sterilization, environmental and instrument contamination with selective microbial and endotoxin sampling • Definition: outbreak control – DLK incidence <2%

  4. Results • Outbreak control - 58/62, two clinics discontinuing LASIK and two closing  • Epidemic curve – to show effects of interventions

  5. Results • Probable  principal causes identified and corrected with outbreak control were: • bacterial/endotoxin contamination of sterilizer reservoirs and short cycle sterilization (16) • ultrasound bath contamination (4) • environmental (4) • silicone oils on gloves (2) • disposable microkeratomes (8)

  6. S Cl Comparison of Different Gloves Glove “A” Glove “B” Glove “C” Glove “D” C – Carbon N – Nitrogen O – Oxygen Na – Sodium Al – Aluminium Si – Silicon P – Phosphorus S – Sulphur Cl – Chlorine K – Potassium Ca - Calcium Silicone Oil

  7. inner tubing to T-piece reservoir brass plug STATIM 2000 Sterilizer

  8. Biofilm: Inner sterilization tubing Gram negative rods encased in biofilm

  9. Intervention • Dry heat sterilization • Modifying or increasing time in steam sterilization • Using disposable instruments • High level of sterile procedure • Enzymatic and biocide cleaning • Improving air quality • Moving clinics • Polymyxin on the stromal bed • Use of sterile distilled water

  10. Discussion • 1998-2004: predominantly sterilization issues, biofilm, endotoxins • 2005-2009: early Femtosecond Lasers, possible lot contamination eg. with disposable microkeratomes, silicone oils on gloves • Recurrences common – protocol breakdown, surveillance important • Canadian study – DLK incidence 0.67% (0.61-0.73, 95%CI), 72% attributed to outbreaks 2000 decreasing to 40% 2003 *Bigham, M et al, JCRS 2005

  11. Conclusions • Review of 62 Diffuse Lamellar Keratitis outbreaks demonstrates most are multifactorial and that sterilization issues and endotoxin contamination appear to be predominant causes • Almost all DLK outbreaks can be successfully controlled

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