Microplastics identified in commercial over-the-counter lubricant eyedrops

There is increasing evidence that microplastics exert harmful effects on human health and on the ocular surface. This pilot study aims to investigate if microplastic particles are present in commonly used eyedrops in single-use plastic vials.

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

All eyedrops analysed contained microplastics. The number of 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 - polyethylene, polypropylene, polystyrene, polyvinylchloride, polyethylene terephthalate, polycarbonate, polymethylmethacrylate, polyamide and polyurethane.

This study provides the most extensive quantification of microplastic contamination in commercial eyedrops to date, highlighting a major, under-recognised source of ocular exposure. These particles may arise from secondary degradation of plastic vials during production, transportation, storage, or during instillation, or introduced from other sources during production and represent a major source of exposure to the ocular surface, especially among patients who require chronic instillation of eyedrops.