Purpose There is increasing evidence that microplastics exert harmful effects on human health and on the ocular surface. Recent studies have highlighted the presence of ocular surface exposure to microplastics via shedding from contact lenses. This study aims to investigate if microplastic particles are present in commonly used eyedrops in single-use plastic vials.

Design Experimental study.

Methods Nine commonly used commercial tear-replacement solutions available without a doctor’s prescription were tested (Brands A-I). All brands of eyedrops were analysed visually using light microscopy and the number of microplastic particles were manually counted. Brands A-F were further analysed using the 8700 Agilent Laser Direct Infrared (LDIR) chemical imaging system to identify the microplastic compositions.

Results All eyedrops analysed contained microplastics. The number of microplastic particles identified using light microscopy ranged between 15 (Brand E) to >18,000 (Brand F). In total, nine types of microplastics were identified with LDIR – an average of 14 polyethylene, 8 polypropylene, 1 polystyrene, 2 polyvinylchloride, 21 polyethylene terephthalate, 1 polycarbonate, 19 polymethylmethacrylate, 23 polyamide and 22 polyurethane per millilitre of eyedrop were identified.

Conclusions This is the first study that identified microplastics in commercial tear-replacement solutions. These particles may have been derived from secondary degradation of the plastic vials (polyethylene) during production, transportation, or storage, and represent a major source of exposure to the ocular surface, especially among patients who require chronic instillation of eyedrops.

The authors have declared no competing interest.

The study was partly funded by the SERI-Lee Foundation Grant (R1845/87/2021).

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