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 quantity of microplastics present in contact lenses.
To analyze the samples, the researchers developed an automated system that captured microscopic images of the lenses, processed the images, and quantified any microplastics found. Their findings, published in the journal Environmental Science & Technology, revealed that lenses exposed to sunlight over time can release tiny fragments of plastic. However, the impact on human health remains unclear.
The researchers collected six different types of contact lenses from various brands and with different lifespans. To simulate normal wear and care, the lenses were stored in water, placed under a lamp that imitated sunlight, and rinsed with water every 10 hours. After the equivalent of 30 or 90 days of sunlight exposure, the water in which each lens was stored was analyzed.
The team found that their new automated system provided quicker and more accurate analyses compared to manual methods when it came to detecting 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, increasing amounts of shed microplastics were observed. Lenses with shorter lifespans showed 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 a day. Although the direct impact of microplastic exposure to eyes on human health is currently unknown, the researchers emphasize the urgent need for further studies in this area.