Minimum endotoxin concentration causing inflammation in the anterior segment of rabbit eyes

Abstract

Purpose: This was a quantitative study to investigate the minimum endotoxin concentration causing inflammation in the anterior segment of the eye.

Methods: Endotoxin was injected intracamerally in pigmented rabbits. A quantitative determination of flare and cells in the aqueous was performed using a laser flare-cell photometer, before and until 72 h after the treatment. An area under the curve (AUC) analysis was employed to evaluate the whole inflammatory reaction regarding flare values.

Results: The time course of flare values in each endotoxin group showed a similar pattern with a peak value at 3 h. An AUC corresponding to values for "average +2sigma", 19301.8 in control eyes, was considered the cutoff value. Using this cutoff value and the regression curve in endotoxin-treated groups, the minimum endotoxin concentration causing inflammation regarding flare values was determined to be 0.60 endotoxin units (EU). Cell counts (cells/0.5 mm(3).0.5 s) corresponding to the value "average +2sigma", 6.07 at 24 h, in control eyes was considered to be the cutoff value. The minimum endotoxin concentration regarding cell counts was determined to be 0.23 EU.

Conclusion: There was a dissociation in response between flare and cells in the aqueous to intracameral endotoxin. The minimum endotoxin concentration causing inflammation ranged between 0.23 and 0.60 EU.