When Leonardo da Vinci first sketched out the concept of a glass lens to correct vision that would cover the eye in 1508, it is unlikely that even he could have visualized the impact that the disposing of disposable contact lenses would have on the environment over 500 years later. Now that over 45 million wearers in the United States alone are using them, researchers at Arizona State University have begun investigating how wearers are disposing of their lenses.

Contact Lens Evolution

Photo by CDC

At first, contact lenses were crafted out of glass and covered the entire eye. The heavy, thick lenses, fashioned in Germany in the late 1880s*, could only be worn for a few hours at a time. Contact lenses evolved from there in 1936, when New York optician William Feinbloom used a combination of glass and hard plastic to construct a more wearable lens. A dozen years later, the lenses switched to all hard plastic until the next evolution came in 1971 when Bausch and Lomb developed soft plastic lenses.

The first disposable lens became available in the United States in 1987, but lenses didn’t become truly disposable as we know them today, until 1995, when one-use lenses were introduced into the market.

Contact Lens Pollution

With millions of users tossing out their soft plastic lenses every day, Arizona State University researchers set out to discover where those lenses end up in the ecosystem in the first-ever study of its kind this year. According to the researchers, they “found that 15 to 20 percent of contact-lens wearers are flushing the lenses down the sink or toilet. This is a pretty large number, considering about 45 million people in the United States alone wear contact lenses, amounting to 1.8-3.36 billion lenses flushed per year, or about 20-23 metric tons of wastewater-borne plastics annually.”

The study goes on to explain that once put down the drain, lenses are then conveyed to wastewater-treatment plants, which then fragment them into microplastics that accumulate in sewage sludge. Researchers noted for that for every two pounds of sludge, a pair of contact lenses can be found.

The short-term solution: throw away your lenses in the trash. Researchers hope that with enough education and awareness paid to this issue, that in the long-term, manufacturers will develop a lens that will biodegrade on its own.

*For a complete history of the contact lens, check out Eye Topics.