Millions of people worldwide wear contact lenses, but a recent pilot study suggests that these lenses may shed microplastics when exposed to sunlight for extended periods. Researchers from the universities of Nanjing and Hohai conducted the study to determine the amount of microplastics present in contact lenses. They developed an automated system that captured microscopic images of the lenses, processed the images, and quantified any microplastics found. The results, published in the journal Environmental Science & Technology, revealed that lenses exposed to sunlight over time can release tiny fragments of plastic, although the impact on health remains unclear.

To conduct their research, the scientists collected six different types of contact lenses from various brands, each with different lifespans. They simulated normal wear and care by storing the lenses in water under a lamp that imitated sunlight and rinsing them with water every 10 hours. After subjecting the lenses to the equivalent of 30 or 90 days of sunlight, they analyzed the water in which each lens was stored.

The team found that their new automated system provided quicker and more accurate analyses compared to manual methods when testing for standard amounts of microplastics. No microplastics were detected in the absence of simulated sunlight. However, when the lenses were exposed to the equivalent of 90 days of sunlight, the researchers observed increasing amounts of shed microplastics. Lenses with shorter lifespans exhibited the highest levels of microplastic shedding after this exposure.

Based on their data from this small-scale study, the researchers estimate that certain lenses could shed over 90,000 microplastic particles per year if worn for 10 hours daily. Although the direct impact of microplastic exposure to the eyes on human health is currently unknown, the researchers emphasize the urgent need for further studies in this area.

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