BLOG: What’s floating in your vitreous? Plastic, partially
Fifty years ago, it was not fully accepted by the medical community that smoking was harmful to health.
I wonder if 50 years from now we will look back with the same wonder about our complacency on the impact of micro- and nanoplastics (MNPs) on our health.
At this point, what we know is that tiny fragments of plastics, smaller than 5 µm in size, make their way into parts of our bodies we’d never expect, and their impact is concerning. If we are wise, we will apply sound scientific methods to better understand the real impact of manmade materials that we eat, drink and inhale constantly.
A 2019 report titled “Plastic & Health: The Hidden Costs of a Plastic Planet” by the Center for International Environmental Law looked comprehensively at health implications with the production and disposal of plastics. At each stage, there appear to be distinct possible harms to human health from the plastics themselves as well as the chemicals used to process them.
Plastics like polystyrene, which is used in everything from coffee cups to orthopedic cushions, are estimated to take 500 years or more to decompose in a landfill. This material, along with polyvinyl chloride, breaks down into tiny fragments that work their way into waterways and are even carried distantly by the wind. They can be deposited directly on plants or absorbed through their roots. Microplastics are also shed by equipment used in food production, construction materials like insulation and the clothing we wear.
Because of their ubiquity, we ingest, inhale and sometimes absorb microplastics through our skin. They are present in virtually all our bodies’ tissues, and recently we have identified their excess presence in areas where inflammation and oxidative stress cause disease. Atherosclerotic plaques in coronary artery disease, for example, have concentrations of MNPs that suggest their role in pathogenesis.
If you’re wondering what impact this all has on the eye, we’re just beginning to understand. A 2024 study, performed at Southern Medical University in Guangzhou, China, showed that microplastics are detected commonly in human vitreous and aqueous specimens, where they are linked to elevations in IOP. Notably, they are also found in patients with retinopathy, suggesting their role in microvascular damage. Age-related macular degeneration too has been linked to polystyrene and other MNPs.
To acknowledge the doubters, it’s true that direct causal relationships between MNPs and most of these diseases have not yet been established. And the body does have some means of clearing some MNPs. Obtaining proof of the causal link to disease may take time, and a surprising number of the studies on this broad topic have occurred in just the past 12 to 24 months. While correlation doesn’t prove causation, there is already plenty of correlation.
In my parents’ day, magazine ads would tout that “two out of three doctors smoke Camels.” Whether that was true then or not, most doctors today don’t think much about the health impact of MNPs. Individually, we have some power to reduce the number and amount of plastics we consume professionally by taking actions like the EyeSustain Pledge. Collectively as a medical field, we have enormous influence on the population to raise awareness, on the medical industry to reduce production and on the government to fund research to better understand and mitigate these potential dangers. We owe it to ourselves and to our successors, who will one day judge our actions, to collect and understand the objective evidence and then sound an alarm that is appropriate to whatever dangers we uncover.
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References:
- Li X, et al. Environ Sci Pollut Res Int. 2024;doi:10.1007/s11356-024-34822-5.
- Plastic & Health: The Hidden Costs of a Plastic Planet. https://www.ciel.org/wp-content/uploads/2019/02/Plastic-and-Health-The-Hidden-Costs-of-a-Plastic-Planet-February-2019.pdf. Published February 2019. Accessed March 10, 2025.
- The surgical facility pledge. https://www.eyesustain.org/facility-pledge. Accessed March 10, 2025.
- Zhong Y, et al. Sci Total Environ. 2024;doi:10.1016/j.scitotenv.2024.171109.
For more information:
John A. Hovanesian, MD, FACS, an ophthalmologist specializing in cataract, refractive and corneal surgery at Harvard Eye Associates in Laguna Hills, California, can be reached at drhovanesian@harvardeye.com.
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