Microplastic contamination in artificial tears in South Korea: Potential for direct ocular exposure

To investigate microplastics (MP) contamination in artificial tear (AT) products.

Five hyaluronic acid ATs (two multi-use and three disposable ATs) were used to gauge MP levels in three scenarios: 1) initial drop and remaining liquid after opening the lid upward; 2) remaining liquid after opening the lid downward and discarding two drops; and 3) remaining liquid after opening the lid downward and discarding half of it. Raman spectroscopy was used to identify the quantity, morphological characteristics, and composition of MPs. Scanning electron microscopy/energy dispersive spectroscopy was used to examine the surface traits and elements of MPs and ATs.

MPs were detected in 4 out of 5 ATs in the initial drops, containing 0.50 ± 0.65 particles/30 mL, whereas the remaining solution had 0.75 ± 0.72 particles/30 mL. After discarding two drops, 0.14 ± 0.35 particles/30 mL were present in the remaining solution. No MPs were detected after discarding half drops. Most MPs were transparent (95 %), irregular fragments (55 %) sized 10-20 μm (35 %), and made of polyethylene (95 %). If patients use the first drops of ATs four times a day for a year, individuals can be exposed to 730.0 particles. This exposure can be reduced to 204.4 particles by discarding the first two drops before use.

MPs are observed in commercially available ATs, and human eyes may be directly exposed to MPs through the use of ATs.