title: Rabbit intraocular reactivity to endotoxin measured by slit-lamp biomicroscopy and laser flare photometry.
abstract: OBJECTIVE
  To evaluate the ocular reactivity of the rabbit to an intracameral injection of a dispersive ophthalmic viscosurgical device (OVD) containing various levels of bacterial endotoxin using slit-lamp biomicroscopy and laser flare photometry.
  
  
  METHODS
  Experimental, randomized, masked animal study.
  
  
  METHODS
  Thirty Dutch-Belted rabbits.
  
  
  METHODS
  The rabbits were randomized into 6 groups to receive 0.05 ml of a hydroxypropyl methylcellulose-based dispersive OVD to which had been added one of 5 different doses of bacterial endotoxin ranging from 0.02 to 1.4 endotoxin units (EUs) or a vehicle control to both eyes. The eyes were evaluated for anterior segment inflammation at baseline and 3, 6, 9, 24, 48, and 72 hours after injection using slit-lamp biomicroscopy and laser flare photometry.
  
  
  METHODS
  Corneal clarity and anterior chamber (AC) inflammation.
  
  
  RESULTS
  All the corneas remained clear throughout the study. Anterior chamber cells were seen at 6, 9, and 24 hours in 60% to 100% of the eyes intracamerally injected with endotoxin-containing OVD, and the response declined rapidly after 24 hours. A dose-response effect was seen between the concentration of endotoxin and the AC cell response. The aqueous flare response in eyes injected with the 2 highest doses of endotoxin was significantly greater (P<0.05) than that of controls. The amounts of fibrin observed in the AC were random, with no apparent dose-response effect seen. The flare values as obtained by laser flare photometry were consistent with the slit-lamp biomicroscopy flare findings up to grade 3+. However, the increase in laser flare value seemed to level off in eyes with more than 3+ flare. Neither measure of flare correlated with endotoxin level.
  
  
  CONCLUSIONS
  Among the parameters evaluated in this study, the AC cell response, evaluated by slit-lamp biomicroscopy and graded using a standard grading system, was found to be the most reliable indicator of the amount of endotoxin in the dispersive OVD. The use of laser flare photometry alone does not seem to be useful in detecting an ocular response to endotoxin contamination in OVDs.
authors.affiliation: National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA.
authors.forename: Robert B
authors.initials: RB
authors.lastname: Nussenblatt
authors.forename: Don
authors.initials: D
authors.lastname: Calogero
authors.forename: Shelley Y
authors.initials: SY
authors.lastname: Buchen
authors.forename: Henry A
authors.initials: HA
authors.lastname: Leder
authors.forename: Margot
authors.initials: M
authors.lastname: Goodkin
authors.forename: Malvina B
authors.initials: MB
authors.lastname: Eydelman
mesh_terms: D000818:Animals; D000869:Anterior Eye Segment / Q000187:drug effects* / Q000473:pathology; D004305:Dose-Response Relationship, Drug; D004340:Drug Contamination; D004731:Endotoxins / Q000633:toxicity*; D065347:Hypromellose Derivatives; D007834:Lasers; D008747:Methylcellulose / Q000031:analogs & derivatives / Q000633:toxicity; D008853:Microscopy; D010783:Photometry / Q000379:methods*; D011817:Rabbits; D014606:Uveitis, Anterior / Q000139:chemically induced* / Q000175:diagnosis; D055675:Viscosupplements
chemical_list: D004731:Endotoxins; D055675:Viscosupplements; D065347:Hypromellose Derivatives; D008747:Methylcellulose