Ocular health risks posed by micro‑ and nano-plastics: A review

Micro- and nano-plastics (MNPs) are ubiquitous environmental contaminants originating from the degradation of plastics and direct release from consumer products. Global plastic production is projected to nearly double by 2050, intensifying human exposure through inhalation, ingestion, and direct ocular contact. This review synthesizes current evidence on the presence, distribution, and health impacts of MNPs in human ocular tissues, their toxicological effects in animal and cellular models, underlying pathological mechanisms, and contributions from ophthalmic materials. A systematic literature search was performed that focused on studies reporting human ocular detection, animal toxicity models (zebrafish, mouse and rat), cellular experiments, and MNPs released from ophthalmic materials, which were included and qualitatively synthesized. MNPs (predominantly PE, PVC, PS, PP) have been identified in human tears, meibomian glands, pterygium, cornea, aqueous humor, vitreous humor, trabecular meshwork and retina at concentrations up to 63.0 μg/g, with particles < 100 µm most prevalent. In animal models, MNPs induce developmental ocular defects, retinal thinning, corneal epithelial damage, goblet cell loss, and blood-retinal barrier disruption. Cellular studies reveal concentration- and size-dependent reductions in viability, elevated oxidative stress, apoptosis, and inflammatory cytokine release. Ophthalmic products including contact lenses, eye drops, and surgical consumables represent significant direct exposure sources. MNPs represent an emerging threat to both ocular surface and intraocular health through oxidative, inflammatory, and barrier-disrupting mechanisms. Reducing environmental and iatrogenic exposure, alongside development of biodegradable ophthalmic materials, is urgently needed to mitigate vision-related risks in an increasingly plastic-contaminated world.