title: Detecting endotoxin contamination of ophthalmic viscosurgical devices: intracameral versus intravitreal assays in rabbits.
abstract: OBJECTIVE
  To compare the sensitivities of intracameral and intravitreal assays in the rabbit model to determine the relative adequacy of these methods in detecting bacterial endotoxin contamination of ophthalmic viscosurgical devices (OVDs).
  
  
  METHODS
  Experimental, randomized animal study.
  
  
  METHODS
  Twenty New Zealand white rabbits.
  
  
  METHODS
  Rabbits were randomized into 4 groups to receive a cohesive or a dispersive OVD via intracameral or intravitreal injection. All 40 treated eyes (10 eyes of 5 animals in each group) received bilateral injection of OVD spiked with bacterial endotoxin at 7.0 endotoxin units/ml. All eyes were evaluated by slit-lamp biomicroscopy for inflammatory response at 3, 6, 9, 24, 48, and 72 hours after exposure. Eyes that received intravitreal injection were also dilated at 24, 48, and 72 hours and were re-examined by slit-lamp biomicroscopy and by indirect ophthalmoscopy.
  
  
  METHODS
  Conjunctival inflammation, anterior chamber (AC) flare, cells and fibrin, vitreous haze and cells, iridal hyperemia, corneal clouding, lens opacities, and onset times.
  
  
  RESULTS
  Intracamerally injected eyes frequently showed conjunctival congestion, AC cells and flare, iridal hyperemia, and fibrin within 6 hours. Up to 80% showed AC cells and flare at 9 hours, and up to 70% showed fibrin at 24 hours. These signs diminished within 48 hours. Fibrin and cells also were seen on the lens surface of most of the eyes. Intravitreally injected eyes showed no signs of inflammation within 24 hours, other than some conjunctival inflammation. After the 24-hour time point, in addition to some conjunctival inflammation, some other signs of inflammation were observed infrequently in the intravitreally injected eyes, including minor vitreous cell reaction in 2 eyes. Although there was 1 dispersive OVD-treated eye with cells and fibrin on the lens capsule at 48 hours, no aqueous cells or flare were seen in the AC of any intravitreally injected eyes at any time during the course of the study.
  
  
  CONCLUSIONS
  The rabbit intravitreal assay, when limited to 72 hours, does not seem to have adequate sensitivity to detect endotoxin reliably in OVDs.
authors.affiliation: Food and Drug Administration, ORISE contractor, Silver Spring, Maryland 20993-0002, USA.
authors.forename: Shelley Y
authors.initials: SY
authors.lastname: Buchen
authors.forename: Don
authors.initials: D
authors.lastname: Calogero
authors.forename: Gene
authors.initials: G
authors.lastname: Hilmantel
authors.forename: Malvina B
authors.initials: MB
authors.lastname: Eydelman
mesh_terms: D000085:Acetates / Q000032:analysis*; D000818:Animals; D000869:Anterior Eye Segment / Q000737:chemistry* / Q000473:pathology; D001681:Biological Assay; D004338:Drug Combinations; D004340:Drug Contamination; D004731:Endotoxins / Q000032:analysis*; D065347:Hypromellose Derivatives; D058449:Intravitreal Injections; D008747:Methylcellulose / Q000031:analogs & derivatives / Q000032:analysis; D008903:Minerals / Q000032:analysis*; D011817:Rabbits; D012965:Sodium Chloride / Q000032:analysis*; D055675:Viscosupplements / Q000032:analysis*; D014822:Vitreous Body / Q000737:chemistry*
chemical_list: D000085:Acetates; C030660:BSS solution; D004338:Drug Combinations; D004731:Endotoxins; D008903:Minerals; D055675:Viscosupplements; D065347:Hypromellose Derivatives; D012965:Sodium Chloride; D008747:Methylcellulose