Noninvasive and Label-Free Sensing of Endotoxin Contamination in Ophthalmic Viscosurgical Devices Using a Fiber-Optic Fourier-Transform Infrared Spectroscopy Based Method

Ophthalmic viscosurgical devices (OVDs) are essential medical tools for ophthalmic surgeons to use routinely in cataract surgery. OVD endotoxin contamination has been implicated in toxic anterior segment syndrome, a severe inflammatory condition after surgery. Current standard methods for endotoxin detection in medical devices rely on dwindling Horseshoe Crab resources for Limulus amoebocyte lysate assay or rabbit intracameral and intravitreal assays. Endotoxin recovery from OVDs poses particular challenge due to the nature and composition of the device. In the present proof-of-concept study, we demonstrate realtime detection capability of endotoxin by employing a noncontact and label-free fiber-optic Fourier transform infrared transmission spectroscopy based sensing method in the midinfrared spectral range of 1.6-12 μm. We performed testing on OVD samples spiked with a series of different concentrations of endotoxin. The study suggested that endotoxin contamination in OVD might be associated with fingerprint spectral peak shift in the wavenumber ranges of 2925-2890 cm
^-1
and 1125-1100 cm
^-1
, and the distance of shifting is dependent upon endotoxin concentration in OVD. FO-FTIR integrated with multivariate approaches such as hierarchical clustering and principal component analysis provides significant differentiation of OVD, endotoxin, and contaminated OVD at different concentrations.