What Are Glasses Lenses Made Of
In most cases, glasses have plastic lenses, or “organic glass,” if you wish to be fancy. But why are so many glasses lens made of plastic?
A plastic lens is usually lighter than a traditional glass lens, which makes it more comfortable to wear. Plastic lenses can also be coated more easily, such as anti-glare. Think about the reason why children’s cups are made of plastic: The material is more resistant to impact.
Check out why lens materials matter for your glasses (and your vision).
Aren’t Some Glasses Made Out of Glass?
Glass is not the only material used to make glasses lenses. Fun fact! Even proto-sunglasses, which predate corrective lenses, were not made from glass, but from quartz instead.
As a result, glass was originally used for most glasses lenses.
Since lens technology has advanced, eyeglass lenses have shifted from glass to plastics. As a result, lens makers are using a variety of high-tech plastics to make lenses with different indexes, hardnesses, and functions. Let us examine the different types of plastics and materials that are used to manufacture modern glass lenses.
Plastic Eyeglasses and Sunglasses Lenses
In order to provide a more comprehensive understanding of the differences between plastic lenses and glass lenses, we will discuss the differences between these four main types of plastics: plastic, Trivex, polycarbonate, and high-index plastics. We will also discuss how a plastic lens compares to a glass lens in the following sections.
Please accept our apologies if things become a little scientific.
Firstly, we have plastic lenses made from CR-39 – a plastic polymer. CR-39 is an abbreviation for “Columbia Resin #39,” which is the 39th plastic of its type made by Columbia Resin, which developed the material.
We then have the glass lenses made from polycarbonate. Polycarbonates were discovered in the 1890s, and they became known in the aerospace industry as “out of this world.” In addition to being transparent and easily shaped, polycarbonate is also an excellent material for optical lenses (glasses) as it can be produced in transparent forms. Additionally, they are impact resistant, making them an excellent choice for children or adults who are likely to be accident-prone.
The lenses made from Trivex are constructed from an impact-resistant, urethane-based pre-polymer plastic. The lenses provide the same level of UV protection as polycarbonate lenses.
Also, there are high-index plastics. They are often composed of sulfur, which provides a higher refractive index, resulting in thinner lenses. The sulfur atoms in these plastics help them produce a higher refractive index. Due to the higher density of these plastics, high-index lenses are heavier even though they are thinner.
What Is The Process Of Making Eyeglass Lenses?
In order to produce plastic prescription lenses, there are several steps involved. The following are the main steps in the process:
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It begins with a lab technician reviewing your prescription, then taking a lens bank (a curved glass or plastic disc that acts as the basis for the lens) that closely matches the prescription.
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It is the technician’s responsibility to grind the lens bank into a shape that matches your prescription as closely as possible, in order to ensure that you have the best vision possible.
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Afterwards, the lenses are edged and cut to fit the glasses frame you have selected.
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After being neatly cut, the lenses are dipped in a solution that protects them from scratches, gives them a tint, or both!
Glass Eyeglasses Lenses
Why are some people still using glass lenses if plastic lenses are the norm for glasses? For starters, certain lenses are most appropriate for certain applications. Despite the advancement of lens technology (to the point where some types of colorblindness can even be corrected), there is no one perfect corrective lens.
Glass lenses have a greater index range than plastic lenses, which is one of the main benefits of prescription eyeglasses or sunglasses. For most individuals, this does not matter, especially for those who do not have an extremely strong prescription. It does, however, for glasses wearers with extremely strong prescriptions.
If you choose mineral glass lenses, you will be able to get thinner lenses with less distortion as well as a physical hardness that makes them more scratch-resistant. Glass eyeglass lenses can be made from different types of glass, including borosilicate, depending on the index and the manufacturer.
There are a number of reasons why you cannot have your glasses lenses made from glass, the main reasons being the weight, fragility, and difficulty of producing glass lenses. Thus, plastic lenses are the preferred choice for most eyewear manufacturers due to their lower cost and lighter weight.
