Glasses Lens Materials - Everything you need to know
There is much more to buying eyeglasses than what first meets the eye. It’s not just choosing the right frame, cool shape, or funky colours. Glasses lens materials also play an important part in picking the right eyewear for you and your vision.
Certain lens materials provide better comfort and visual clarity, and some are available in many lens designs. It may seem like a lot to take in but this article will guide you through the main points of the different lens materials out there!
What are the different materials for eyeglass lenses?
There are 5 main types of lens materials for eyeglasses and sunglasses. Each type of lens material can help correct refractive errors such as nearsightedness, farsightedness, astigmatism, or presbyopia.
Before going into the different materials, it can be good to understand the index of refraction. Some materials are categorized by the index of refraction, which indicates how fast light travels through a given material.
Essentially, the higher the refractive index of a material, the slower light moves through it, which results in a greater bending (refracting) of light rays. With a higher refractive index, less lens material is required to bend light to the same degree as a lens with a lower refractive index.
In other words, for any eyeglass prescription, a lens made of a material with a high-refractive-index will be thinner than a lens made of a material with a lower refractive index.
Now to the 5 main materials:
Glass lenses are among the best lens material in providing visual clarity and being highly scratch resistant, due to their hard surface.
However, glass lenses are heavy, thick, and have a lower impact resistance. In many cases, glass lenses have to be specifically treated to comply with impact-resistant regulations and can not always fit in every frame design.
Plastic (CR-39) is the standard glasses lens material. Compared to glass lenses, plastic lenses are lighter and less likely to shatter as easily. Plastic lenses offer great optics and vision correction for refractive errors and block out 80% of UV light.
However, CR-39 plastic lenses tend to be thicker than other plastic materials as they have a lower index of refraction.
Polycarbonate lenses have a higher index, higher impact resistance, and superior UV protection than standard plastic lenses. Polycarbonate lenses are more prone to scratches and thus adding an anti-scratch coating will help keep your lens clear.
These thinner and durable polycarbonate lenses are for sure a popular choice among glasses wearers. If you have an active lifestyle and need safety glasses for work or leisure, then polycarbonate lenses are a great pick. They are also recommended for kids’ glasses.
Glasses that require a higher prescription and are fitted with polycarbonate lenses can cause chromatic aberration (see image below). Chromatic aberration is the distortion of an image caused by the lens not being able to focus all colours on the same point. This happens because the lenses have a lower abbe value which means a higher dispersion of light - hence the light does not focus on one exact point.
Trivex lenses are another great choice for children’s eyewear and safety glasses as they have a higher impact resistance. Trivex lenses are also thinner and lightweight, offering exceptional optics and very low chromatic aberration due to their higher abbe value. This means that trivex lenses can provide a clearer and crispier visual experience.
Just like the CR-39, the trivex lens has a lower index of refraction, causing the lens to be thicker with a higher prescription.
High index lens materials are the thinnest and lightest of them all. High index lenses can be used for stronger prescriptions as they look more aesthetically pleasing with thinner lenses. High index lenses bend light more efficiently as they have a higher index of refraction.
High index lenses have superior optics and impact resistance but these factors can depend on the type of high index material used - glass or plastic. Like many other lens materials, high index lenses provide quality UV protection.
Lens coatings can also be an important factor to keep in mind when choosing lens materials for your glasses.
Glass lenses due to their hard surface are less prone to scratches compared to plastic lens materials. So adding on anti-scratch coatings will help protect plastic lenses from damages.
With high index lenses or polycarbonate, you’ll want to make sure you add an anti-reflective coating to avoid the lenses reflecting too much light - especially when driving.
With many lens materials, you can also add zFORT® Blue light blocking to help protect your eyes from harmful rays emitted by digital devices.
Photochromic filters can be added to nearly all the diverse lens materials and designs. A pair of glasses that also function as sunglasses - 2-in-1!
Read our guide on lens coatings to learn more!
What lens material is best?
To determine what lens material is best for you, you should have an eye test to determine the requirements of your vision correction. You should also always consult your optician or eye doctor first to find the best suitable lens material for your specific vision correction.
Once you have consulted your optician and have your prescription, you want to think about the following things when choosing your lens material:
• Cost (optional if you don’t mind spending a little more)
Plastic lenses (CR-39) are the most affordable lens material and work better for weaker Rx.
Glass lenses are also low-cost but are difficult to pair with certain frame designs and sizes.
Polycarbonate lenses and trivex lenses are similar but do present some differences. While trivex lenses have better optic quality, polycarbonate lenses have more available lens design options, like progressive lenses.
High index can work best if you want thinner lenses but they do come at a higher cost.
Are thinner lenses better?
If you wear glasses every day you’ll want them to fit comfortably, look good, and not way heavily on your face. Thinner lenses can tick all boxes. Thicker lenses are more noticeable in the frame and tend to be heavier.
Thicker lenses are, however, more affordable and suitable for lower vision corrections. Alternatively, thinner lenses are suitable for any refractive error and look better - prices can vary.
Whether you prefer the ‘coke bottle’ effect or thin sleek lenses, you can discover everything there is to know about glasses lens materials and which may be the right fit for you.
If you want to find affordable glasses for an everyday fit, that don’t break easily, still provide great optics, and have a little thickness then standard plastic lenses could be what you are looking for. Or maybe you don’t mind splurging a little and finding higher quality specs that offer protective filters and are nicer looking. Then glasses with polycarbonate or high index lenses are right up your alley.
With SmartBuyGlasses browse through endless trendy eyewear to accommodate your every eye need and find informative advice about how to choose the right glasses here. Our lenses are made from quality plastic materials for which you can pick the lens index best for you. So why not scroll back up and start by choosing the best lens materials for you and your vision.