Objective: To determine the safe local concentration of gentamicin.
Methods: The authors studied the toxicity of gentamicin (no preservative) on 3 types of human corneal cell in culture with different concentrations.
Results: There was no toxic effect on the corneal epithelium, stroma and endothelium with gentamicin 1 mg. per milliliter in 48 h. in vitro, while the concentration was up to 2 mg. or 4 mg. per milliliter, all types of corneal cells appeared cytopathic effect (CPE), the toxicity of gentamicin to the corneal cells is in direct proportion to its concentration and time term of incubation, and the toxicity was the greatest on endothelium, slightest on stroma:
Conclusion: It is suggested that the safe dosage of local concentration of gentamicin be 1 mg. per milliliter in human eyes.