Implications of polyethylene exposure based on in vitro studies of human cells and in vivo studies of mice, where IL refers to cytokines and IFN to interferon. Credit: Elsevier from: Wang J et al

Identification of microplastics in human tear fluid and meibum: Implications for dry eye disease pathogenesis 

Jingyi Wang et al

J Hazard Mater. 2025 Feb;489:137635 

Review: This cross-sectional, lab-based study investigated the presence and potential role of airborne microplastics (MPs) in dry eye disease (DED) by analysing tear fluid and meibum samples from 45 patients with DED. Using pyrolysis-gas chromatography-mass spectrometry, laser direct infrared imaging and scanning electron microscopy, five types of MPs were identified – predominantly polyethylene (PE). 

In tear fluid, higher levels of PE and polyvinyl chloride (PVC) were significantly associated with DED severity markers, including reduced tear secretion (Schirmer test) and shorter tear film breakup times. In meibum, PE content per unit of residual meibomian gland area was negatively correlated with lipid layer thickness, while PVC content was positively associated with increased partial blink rate. 

In vitro, PE exposure reduced viability and increased apoptosis in human corneal and conjunctival epithelial cells. In vivo, topical PE application in mice led to goblet cell loss, conjunctival inflammation and DED-like symptoms (Fig 1). 

Comment: This is the first study to detect microplastics in human tear fluid and meibum and to investigate their impact on the ocular surface. PE and PVC levels increased with age, suggesting environmental accumulation over time. Together, the clinical, in vitro and animal model data offer compelling evidence that MPs may contribute to ocular surface dysfunction. Limitations include the small sample size, lack of healthy controls and exclusion of other MP types, which limit generalisability. Nonetheless, the study underscores the potential health risks of airborne plastic exposure and highlights the need for further research and stronger environmental policy. 

A randomized, vehicle-controlled, phase 2b study of the TRPM8 receptor agonist AR-15512 in the treatment of dry eye disease (COMET-1) 

David Wirta et al

Ocul Surf. 2022;26:166–173 

Review: In recent years, growing attention has been direected towards the neuronal regulation of tear production. The trigeminal nerve provides parasympathetic stimulation of the lacrimal functional unit, while sensory input from the cornea and conjunctiva is crucial for initiating basal tear production. Transient receptor potential melastatin 8 (TRPM8) receptors are responsible for detecting ocular surface cooling and hyperosmolarity, which triggers tear secretion. 

AR-15512, a TRPM8 receptor agonist, was tested as a potential treatment for DED. This phase 2b multicentre, randomised, double-masked, vehicle-controlled trial evaluated two concentrations of AR-15512 in 369 patients with DED over 12 weeks. Eligible patients were aged 30 or older, with documented DED symptoms and clinical signs. 

Patients received either 0.0014% AR-15512, 0.003% AR-15512, or vehicle drops, twice daily. The 0.003% dose showed significant improvement in multiple DED symptoms (SANDE, ocular discomfort score (ODS-VAS), Eye Dryness-VAS) and signs (unanaesthetised Schirmer scores, ocular surface staining, tear meniscus height, hyperaemia) at various timepoints. However, the study did not meet its predefined co-primary endpoints (anaesthetised Schirmer score and ODS-VAS on day 28). The most frequent side effects were mild, transient stinging or burning. 

Comment: Although the co-primary endpoints weren’t met, AR-15512 appears promising as a symptom-relieving treatment that stimulates tear production via neurostimulation. Improvements were seen early and maintained throughout the 12-week period, with good tolerability. Future studies should refine endpoint selection and timing, include longer follow-up duration, record more details regarding the burning and stinging effects upon instillation and possibly stratify patients by baseline dry eye subtype and symptom severity to better capture treatment benefits. Overall, AR-15512 shows potential for real-world use and has now been FDA approved for the treatment of signs and symptoms of DED.

Ocular adverse effects of over-the-counter cosmetics and personal care products reported to the Food and Drug Administration (FDA)

Aretha Zhu et al

Ophthalmic Plast Reconstr Surg. 2025;41(1):61–66 

Review: This retrospective study analysed ocular and periocular adverse events (AEs) associated with over-the-counter cosmetic and personal care products, as reported to the FDA’s Center for Food Safety and Applied Nutrition Adverse Event Reporting System (CAERS) between January 2004 and June 2022. 

From over one million reports in the database, 61,421 involved cosmetic-related AEs, with 959 unique periocular and 1,382 unique ocular AEs identified. In total, 1,711 periocular and 2,485 ocular AEs were reported, and inflammation (45%) and hypersensitivity (19%) being the most common periocular reactions, with discomfort (38%) and inflammation (29%) being the most common ocular effects. 

Hair products were associated with the highest rate of ocular complications, as well as the greatest incidence of disability and life-threatening outcomes. Permanent cosmetics were most frequently associated with periocular AEs. The most commonly reported outcome was a visit to a healthcare provider, while hospitalisation and required interventions were rare. 

Comment: The voluntary nature of CAERS reporting means the true incidence of these events could be underrepresented. Notably, reporting of ophthalmic AEs rose steadily until 2018 before declining, possibly due to decreased cosmetic use and healthcare access during the Covid-19 pandemic. Furthermore, information on the mechanism of action, duration of symptoms, or what type of management or treatment was initiated, is currently not available in the reporting system. Therefore, the database cannot identify the specific chemicals/materials of the products that resulted in the AE. The outcome of this study highlights the importance of communicating with patients with ocular surface symptoms about their use of cosmetics and personal care products, which can migrate onto the eye surface, causing disruptions to the tear film and meibomian gland function. 

Dr Ally Xue is a therapeutic optometrist and postdoctoral research fellow at the University of Auckland’s Ocular Surface Laboratory, with a special interest in light-based therapies for dry eye.