Impact of Microplastics on the Ocular Surface

Abstract

Plastics are synthetic materials made from organic polymers that are ubiquitous in daily living and are especially important in the healthcare setting. However, recent advances have revealed the pervasive nature of microplastics, which are formed by degradation of existing plastic products. Although the impact on human health has yet to be fully characterised, there is increasing evidence that microplastics can trigger inflammatory damage, microbial dysbiosis, and oxidative stress in humans. Although there are limited studies investigating their effect on the ocular surface, studies of microplastics on other organs provide some insights. The prevalence of plastic waste has also triggered public outcry, culminating in the development of legislation aimed at reducing microplastics in commercial products. We present a review outlining the possible sources of microplastics leading to ocular exposure, and analyse the possible mechanisms of ocular surface damage. Finally, we examine the utility and consequences of current legislation surrounding microplastic regulation.

Microplastics Identified in Commercial Over-the-counter Lubricant Eyedrops

“…Owing to its small size, microplastics have a high surface-area-to-volume ratio and bioaccessibility and can exert harmful effects at a cellular level 20 . These are postulated to occur via three main mechanisms - inflammation and oxidative damage, microbial dysbiosis and toxicological effects from additives and sequestrated chemicals 16 .…”

“…This study employed two different methods to determine the presence of microplastics in commercially available tear-replacement solutions. A range of techniques have been described in the literature to analyse microplastics 16 . These include non-destructive methods such as transmission electron microscopy, scanning electron microscopy, atomic force microscopy, Raman spectroscopy, atomic force microscopy, and destructive methods such as thermal analysis using pyrolysis or thermal desorption gas chromatography-mass spectrometry (Pyr/TD-GC-MS), and other thermogravimetric analysis (TGA)-based method 16 .…”

“…A range of techniques have been described in the literature to analyse microplastics 16 . These include non-destructive methods such as transmission electron microscopy, scanning electron microscopy, atomic force microscopy, Raman spectroscopy, atomic force microscopy, and destructive methods such as thermal analysis using pyrolysis or thermal desorption gas chromatography-mass spectrometry (Pyr/TD-GC-MS), and other thermogravimetric analysis (TGA)-based method 16 . There is no consensus on a standardised approach to processing and analysing samples for microplastics.…”

“…LDIR is an infrared spectrometer that utilises a fast-tuneable quantum-cascade laser (QCL) coupled with a rapidly scanning imaging system to analyse particulate information such as quantification, size, colour and morphology, while identification of polymer type can be identified with spectroscopic analysis 16 .…”

Utilization of Nitrogen-Doped Graphene Quantum Dots to Neutralize ROS and Modulate Intracellular Antioxidant Pathways to Improve Dry Eye Disease Therapy

“… 6–8 Moreover, its prevalence escalates with aging and environmental exposures. Triggering environmental factors may include low humidity, atmospheric pollutants like ozone or microplastic residues 9 to UV radiation, cosmetic eye products, 10 and even electronic device usage. 11 Under typical conditions, biological antioxidant systems keep ROS in check; however, prolonged oxidative stress is known to disrupt the redox balance, 12 , 13 leading to reduced lacrimal gland function and oxidative harm to crucial biomolecules, such as proteins, lipids, and nucleic acids.…”