Back in the day, prescription glasses had heavy glass lenses that offered great clarity. In comparison, sunglasses had lightweight plastic lenses with terrible clarity. Fortunately, we are no longer back in the day.
Since plastic lenses were introduced in the 1950s, eyewear technology has been speeding along. Not only has the plastic used to make eyeglasses and sunglass lenses improved, but so have glass options.
And there are even still glass lenses out there in sunglasses! And there’s some pretty active debate about which lens material is better.
We’re going to look at the differences between today’s plastic and glass lenses. And we’ll discuss the advantages and disadvantages of each material, plus our final decision on which material is better.
Polycarbonate vs. Glass Lenses – What’s the difference?
Clarity and Quality
Those original opticians had it right when it came to optical clarity. Glass lenses can’t be beaten. And that’s why when exact precision is needed, say in microscopes, cameras, or telescopes, glass is still the standard.
But that doesn’t mean polycarbonate or plastic lenses are not clear. High-quality polycarbonate lenses offer excellent clarity for a pair of eyeglasses or sunglasses.
The truth is that our eyes can’t really detect the difference in clarity between glass and high-quality polycarbonate. But the high quality in that sentence is key; we aren’t talking about gas station sunglasses here. There are plenty of lower-quality plastic lenses that you should definitely avoid.
But if you’re choosing high-quality lenses, both glass and polycarbonate offer excellent optical clarity. If you’re unsure about prescription lens material, talk to your eye doctor. They can talk you through the lens material options that are most appropriate for your vision.
Impact Protection
This is the area that really differentiates between glass and polycarbonate lenses. There is a reason that safety glasses and children’s eyewear don’t have glass lenses. And that reason is impact protection.
Even the most modern glass lens is more likely to break or shatter than a polycarbonate lens. That’s because Polycarbonate flexes instead of shattering when hit by an object, whether it’s gravel, a ball, or an elbow. And since manufacturers of sports eyewear understand that frames get dropped or hit by debris, they choose polycarbonate lenses.
But lifestyle sunglasses also need impact protection. Whether you’re driving your car or walking down the street, you still want to protect your eyes. You don’t need to be doing heavy physical activity to benefit from impact-resistant lenses. Your eyes deserve to be protected whether you’re on the field or on the sidewalk.
Weight
Glass lenses used to be really heavy. And wearing them for long periods of time was a chore. One of the biggest selling points of early plastic lens material was that it was lightweight and offered all-day comfort.
Today, even though glass lenses are thinner than they used to be, polycarbonate lenses are still the lighter choice. And if you combine them with a lightweight frame material like titanium or nylon, you’re set for a full day of comfortable wear.
Final Decision: Polycarbonate or Glass – Which is Better?
Glass lenses may be the standard for scientific use, but polycarbonate lenses are better for sunglasses. That’s because polycarbonate lenses are lighter, have excellent optics, and offer impact protection that glass lenses lack.
We also like them for their ultraviolet protection. Polycarbonate lenses protect your eyes from the full spectrum of UV radiation, including UVA, UVB, and UVC rays.
The combination of impact and UV light protection makes polycarbonate the best choice for both lifestyle and sports sunglasses.
Advantages and Disadvantages of Polycarbonate and Glass Lenses
While we prefer polycarbonate lenses, both types have advantages and disadvantages. Check out our useful diagram below and a quick rundown of both types of lenses:
Glass Lens Advantages
- Outstanding clarity
- Naturally resists scratches without a scratch-resistant coating
Glass Lens Disadvantages
- Lack of UV protection without a coating
- Heavier than plastic lenses
- May break and shatter with impact
Polycarbonate Lens Advantages
- Impact and shatter-resistant
- Very lightweight
- Excellent strength and durability
- Protect from UV rays
Polycarbonate Lens Disadvantages
- Less scratch-resistance than glass without a coating
- Slightly less optical clarity
Frequently Asked Questions
Can Polycarbonate Lenses Crack?
Yes, polycarbonate lenses can crack. But if your polycarbonate lenses do break, they are less likely to shatter into small, harmful pieces. If your polycarbonate sunglass lenses do crack, check the manufacturer to see if they offer replacement lenses.
Are Polycarbonate Lenses Safe?
Yes, Polycarbonate is a safe material for your sunglasses. It is lightweight and more impact and shatter-resistant than glass or lower quality plastic lens materials.
Is Polycarbonate Plastic?
Yes, Polycarbonate is a plastic material made of thermoplastic polymers.
Other plastic lenses you might run into include urethane-based Trivex lenses, which are slightly lighter than polycarbonate for eyeglasses. CR-39 plastic lenses are regular plastic lenses you might find in very inexpensive sunglasses.
Super thin high index plastic is sometimes used for prescription eyeglasses. This plastic tends to reflect a lot of light, leading to glare. They usually need an anti-reflective coating.
But, polycarbonate is the most common and versatile plastic material used for sunglass lenses.
Ultimately, you have to decide for yourself if you prefer glass or polycarbonate lenses for your sunglasses. Some companies use exclusively one or the other, some offer both. It may come down to what styles and brands you like typically use.
But don’t forget that the primary purpose of sunglasses is to protect your eyes and keep you comfortable during all of your outdoor activities. If a brand you love isn’t using lenses that offer impact and UV protection, make your voice heard.
You only get one pair of eyes, so use your sunglasses to protect them. You can look great and be safer with the right lenses.
Want to Know More?
Have a question about Polycarbonate vs. Glass lenses? Or want to know more? Let us know in the comments below!
