title: Efficacy and safety assessment of a novel ultraviolet C device for treating corneal bacterial infections.
abstract: BACKGROUND
  A prototype solid-state Ultraviolet-C (UVC) LED device may be useful in the treatment of corneal microbial infections, as UVC is commonly used for eradicating bacteria, fungi and viruses in other settings. This study assessed the efficacy of 265 nm UVC from this LED, on four different bacterial strains, and investigated the consequences of corresponding exposures on human corneal epithelial cells in vitro.
  
  
  METHODS
  Agar plate lawns of Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Streptococcus pyogenes were exposed to a 4.5 mm diameter 265 nm UVC beam at a fixed intensity and distance, for 30, 5, 4, 2 and 1 seconds. Growth inhibition was assessed with a BioRad Gel imager, and the diameter of lucent areas of bacterial inhibition recorded. Human corneal epithelial cells cultured on glass cover-slips were exposed to corresponding doses of UVC from the same device. Live/dead staining was performed and the results quantified.
  
  
  RESULTS
  There was 100% inhibition of growth for all bacteria tested, at all exposure times. A 30-second exposure of human corneal epithelium to UVC gave no statistically significant decrease (P = 0.877) in the ratio of live to dead cells when compared to control cultures.
  
  
  CONCLUSIONS
  The results confirmed that a 1 second exposure to germicidal UVC from this LED source was sufficient to inhibit microbial proliferation in the four bacterial strains tested in vitro. The literature suggests UVC at this dose could potentially be beneficial in treating corneal surface infections, without causing significant adverse effects, supported by our findings in human corneal epithelium exposed to UVC.
authors.affiliation: University of Auckland, Auckland, New Zealand. simondean@xtra.co.nz
authors.forename: Simon J
authors.initials: SJ
authors.lastname: Dean
authors.forename: Alex
authors.initials: A
authors.lastname: Petty
authors.forename: Simon
authors.initials: S
authors.lastname: Swift
authors.forename: Jennifer J
authors.initials: JJ
authors.lastname: McGhee
authors.forename: Anant
authors.initials: A
authors.lastname: Sharma
authors.forename: Sunil
authors.initials: S
authors.lastname: Shah
authors.forename: Jennifer P
authors.initials: JP
authors.lastname: Craig
mesh_terms: D001419:Bacteria / Q000528:radiation effects*; D002478:Cells, Cultured; D015169:Colony Count, Microbial; D003320:Corneal Ulcer / Q000382:microbiology / Q000532:radiotherapy*; D019573:Epithelium, Corneal / Q000528:radiation effects*; D004926:Escherichia coli / Q000528:radiation effects; D015818:Eye Infections, Bacterial / Q000382:microbiology / Q000532:radiotherapy*; D006801:Humans; D010865:Pilot Projects; D011550:Pseudomonas aeruginosa / Q000528:radiation effects; D013211:Staphylococcus aureus / Q000528:radiation effects; D013297:Streptococcus pyogenes / Q000528:radiation effects; D016896:Treatment Outcome; D014466:Ultraviolet Rays; D014467:Ultraviolet Therapy / Q000009:adverse effects / Q000295:instrumentation*