The Hidden Plastic Problem In Contact Lenses

Contact lenses are made of plastic, with soft and hard lenses differing in their exact makeup. Soft contacts are made of hydrophilic plastics called hydrogels, which are highly water-absorbent, while hard lenses are made of an acrylic-type polymer. A year's worth of disposable lenses, 730 lenses in total, equals approximately 9,125 grams of plastic, which is less than the plastic needed to produce two credit cards. However, contact lenses are not biodegradable and are very hard for recycling plants to process, so they often end up in landfills. Additionally, lenses exposed to sunlight over time can shed tiny fragments of plastic, known as microplastics, which can pollute waterways and harm the environment and animal life.

Soft contact lenses are made of hydrophilic plastics called hydrogels

Soft contact lenses are made of flexible plastics that allow oxygen to pass through to the cornea. They are often more comfortable than rigid gas permeable lenses and are easier to adjust to. Newer soft lens materials include silicone hydrogels, which provide even more oxygen to the eye. Silicone hydrogels are also used in contact lenses designed for extended wear, helping them to maintain their moisture.

The first contact lenses were made of glass and were large, uncomfortable, and could only be worn for a few hours at a time. In 1938, perspex (polymethylmethacrylate, or PMMA) began to replace glass in contact lens manufacture. PMMA lenses were easier to produce, but they had no oxygen permeability, and many people could not tolerate or safely wear them. Today, soft contact lenses are often made with polyhydroxyethylmethacrylate (pHEMA), a material first used in 1961 by Czech chemical engineer Otto Wichterle.

While contact lenses are made of plastic, the amount of plastic waste they generate is relatively small. A year's worth of disposable lenses (730 lenses) equals approximately 9,125 grams of plastic, which is less plastic than two credit cards. Additionally, most of the packaging that lenses come in is recyclable. However, contact lenses cannot be recycled and do not biodegrade, so they end up in landfills. They can also break down into microplastics that pollute waterways and harm the environment and animal life.

Hard contact lenses were made of a hard plastic material called polymethyl methacrylate (PMMA)

Contact lenses are made of plastic, with soft and hard lenses differing in their exact makeup. Hard contact lenses were made of a hard plastic material called polymethyl methacrylate (PMMA).

PMMA is a synthetic resin, or plastic, that is created through the process of polymerization. In simple terms, this means that a source material (methyl methacrylate) is placed into a mold in combination with a catalyst, causing a chemical reaction. This results in the formation of long and very stable chains of molecules.

PMMA was first discovered in 1893, and a few decades later, it was developed into Plexiglas by a German pharmacist named Otto Röhn. This plastic is strong, durable, scratch-resistant, easy to install, and can be shaped into various forms, making it incredibly useful in multiple fields.

In the context of contact lenses, PMMA was once considered the best material. When the first mass-market contact lenses were developed in the 1940s, they were all made of this rigid, nonporous PMMA material. However, PMMA acts as a plastic shield that keeps oxygen away from the eye, which is necessary for the cornea to stay healthy. This led to the development of smaller PMMA lenses to reduce the area they covered, but these lenses tended to fall out easily.

Today, PMMA lenses are rarely used. Researchers have developed new silicone-containing rigid contact lens materials that are gas permeable, allowing oxygen to reach the cornea directly. These newer materials are also more flexible, providing greater comfort and improved corneal nutrition.

Silicone hydrogel lenses are made of a soft water-based plastic material

Contact lenses are made of plastic, with soft and hard contacts differing in their exact makeup. Soft contact lenses are made of hydrogels, hydrophilic plastics that are highly water-absorbent, allowing them to stay moist and flexible. The "breathability" of the lens, or the amount of oxygen that can pass through to the eye, increases with higher water content.

The silicone in the lenses increases the oxygen permeability, boosting the amount of oxygen that can pass through the lens to the cornea. This makes them healthier than regular soft lenses and reduces the risk of hypoxia, a condition where the cornea's oxygen supply is significantly reduced, causing red eyes, corneal swelling, blurred vision, and eye discomfort.

Silicone hydrogel lenses are also used for specific contact lens designs that require greater lens mass, such as toric contacts for astigmatism, bifocal contacts, and lenses for hard-to-fit eyes. However, one drawback is their tendency to collect more debris and protein deposits from tears.

While contact lenses are made of plastic, there are ways to reduce their environmental impact. For example, contact lenses and their packaging can often be recycled, and buying in bulk can reduce waste. Additionally, donating used eyeglasses and contact lenses to charity can help those in need and reduce waste.

A year's worth of disposable lenses equals approximately 9,125 grams of plastic

Contact lenses are made of plastic. Soft contact lenses are made of hydrophilic plastics called hydrogels, which are highly water-absorbent, while hard contact lenses are made of an acrylic-type polymer. The most common types of contact lenses are hydrogel and silicone hydrogel, which are known as soft contact lenses.

A year's worth of disposable lenses, 730 lenses in total, equals approximately 9,125 grams of plastic. This is calculated by multiplying the weight of a pair of soft contact lenses, which is about 25 milligrams, by the number of pairs of lenses used in a year. For example, if you wear bi-weekly lenses, you will use twenty-six pairs of lenses, or 0.65 grams of plastic, in a year.

The amount of plastic in a year's worth of disposable lenses may sound like a lot, but it is important to consider the environmental impact of other options. For example, switching to reusable contact lenses can reduce the amount of plastic waste generated, but it is important to properly dispose of contact lenses to avoid contributing to microplastic pollution. Contact lenses should not be flushed down the drain or toilet, as they can break down into microplastics that can harm the environment and animal life.

Additionally, while wearing glasses may seem like a greener option, most glasses contain laminated acetate, which is derived from non-renewable oil and is not biodegradable. The production and disposal of glasses can also contribute to environmental damage, especially considering that people often buy new eyeglasses every two years or so.

Contact lenses can break down into microplastics that pollute waterways

Contact lenses are made of plastic—specifically, soft and hard lenses are made of hydrophilic plastics, or hydrogels, which are highly water-absorbent. This allows them to stay moist and flexible.

Contact lenses are not biodegradable, and their small size makes them difficult to process in recycling plants. As a result, used contact lenses often end up in landfills, or are flushed down sinks and toilets. However, flushing contact lenses contributes to microplastic pollution in waterways, according to researchers at Arizona State University.

When contact lenses are mixed with microbes in wastewater, they lose their structural strength and break down into smaller and smaller pieces, eventually becoming microplastics. These microplastics cannot be filtered out like larger plastics, and can make their way back into nature. They can enter rivers, lakes, and oceans through runoff when it rains, or when there are overflows at treatment plants.

A study by the American Chemical Society found that contact lenses shed microplastics when exposed to sunlight, with lenses with shorter lifespans showing the greatest amount of shed microplastics. The researchers estimated that more than 90,000 microplastic particles per year could be shed from some lenses if worn for 10 hours a day.

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