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Updated: Jun 22, 2026
Detection of Endotoxin in Nano-formulations Using Limulus Amoebocyte Lysate (LAL) Assays
Published on: January 30, 2019
Detection of pyrogens adsorbed to intraocular lenses: evaluation of limulus amoebocyte lysate and in vitro pyrogen
Liliana Werner1, Manfred Tetz, Khalid Mentak
1Berlin Eye Research Institute, Berlin, Germany. werner.liliana@gmail.com
Purpose:
To determine the ability of the limulus amoebocyte lysate (LAL) assay and the in vitro pyrogen test (IPT) to detect pyrogens adsorbed to intraocular lenses (IOLs).
Setting:
Berlin Eye Research Institute, Berlin, Germany.
Methods:
Fifteen of each of the following IOLs were used: MicroSil MS 612 ASP, AcrySof SA60AT, Superflex, Sensar, XACT, and LS-106 IOLs. The challenge organism suspensions were 10(3) CFU/mL and 10(4) CFU/mL Escherichia coli, 10(3) CFU/mL and 10(4) CFU/mL Pseudomonas putida, and 10(5) CFU/mL and 10(6) CFU/mL Staphylococcus epidermidis. Two IOLs of each model were incubated at room temperature for at least 2 days in 0.6 mL of 1 of the suspensions. They were then gamma sterilized. The extract of 1 IOL was tested with the LAL assay; the other IOL was tested with the IPT.
Results:
The LAL was negative for all incubated IOLs. The IPT was positive for all IOLs incubated in E coli and P putida suspensions, with the MicroSil MS 612 ASP, AcrySof SA60AT, XACT, and LS-106 IOLs showing a severe reaction. The Superflex and Sensar IOLs had a slight to moderate response for lower bacterial concentrations and a moderate to severe response for higher concentrations. For S epidermidis, all IOLs showed a slight IPT response except XACT IOLs, which showed a nonpyrogenic response.
Conclusions:
Results indicate that the LAL test may fail to detect pyrogens adsorbed to IOLs and the IPT reliably detects pyrogens with a dose-dependent response. This has relevance in the investigation of toxic anterior segment syndrome outbreaks.
