Assessing Particle Release from Intraocular Lenses with a Combination of OptoFluidic Force Induction, μ-Raman and μ-FTIR

Intraocular lenses (IOLs) are among the most common medical implants that remain in the body long-term, with millions of IOLs implanted into patients every year. In addition, there are rapidly growing concerns about microplastic pollution, including particle emission from medical implants directly inside the body. Against this backdrop, we analyze the particle emission of seven common types of IOLs over a 30-day period under laboratory conditions. To accomplish both particle counting over a long period and chemical identification, we combine OptoFluidic Force Induction (OF2i), a novel online particle counting method, with micro Fourier Transform Infrared Spectroscopy with Attenuated Total Reflection (μ-FTIR-ATR) and Raman microscopy. Encouragingly, over the 30-day period, no significant particle emission from the IOLs was detectable. Neither was any increase in particle count detectable by OF2i, nor could any particle related to IOL material be found out of over 500 particles analyzed on non-control samples by FTIR and Raman microscopy. The most notable limitation of these results is the 30-day period, which is short compared to the time an IOL stays in the patient, which can be years or even decades. However, two of the tested IOLs were stored in liquid in their original packaging, the analysis of which represents a less-controlled long-term version of our study. Whilst microplastic contamination was found in these liquids, the FTIR and Raman analysis showed that it relates to the packaging materials (PE, PP) rather than the IOLs (acrylic), pointing to a high stability of the IOLs. Future work should try to assess longer time frames with accelerated aging (thermal/UV/oxidative conditions) to approximate long-term in vivo scenarios. Moreover, our findings highlight the need for manufacturers to ensure maximum stability of packaging materials and packaging methods to minimize potential microplastic contamination.