A Guide to High-Index vs. Polycarbonate Lenses
November 23, 2022 • 10:03 AM
Whether it’s the first or umpteenth time, picking out new lenses for your eyeglass prescription can be a little overwhelming. After all, there’s a plethora of choices. You might need single-vision lenses to tackle myopia (nearsightedness), astigmatism (an irregularly shaped cornea), and hyperopia (farsightedness). There are also bifocals and progressive lenses for those who need to toggle between near and far vision.
And then there’s the lens material to think about. From high-index and polycarbonate lenses, there's a lot to consider when choosing a lens type.
That’s why we created this guide on high-index vs. polycarbonate lenses. Focusing on these two commonly used lens materials, you’ll learn their pros and cons to decide which eyeglass lenses you should choose.
High-Index vs. Polycarbonate Lenses 101
Let’s begin by finding out what high-index and polycarbonate lenses are.
What Are High-Index Lenses?
High-index lenses are made of plastic lens material with a high refractive index.
For those new to the concept, the refractive index measures how light travels through the material, aka refraction. Different materials have different refractive indexes.
For example, standard plastic lenses — like the basic Columbia Resin 39 (CR-39) lens — typically range from 1.48 to 1.54. Meanwhile, high-index and ultra-high-index lenses rank at around 1.64 and beyond.
What Are Polycarbonate Lenses?
Polycarbonate lenses, also called “Poly C” lenses, are a type of plastic lens widely used in prescription and non-prescription glasses. They are especially popular for kids’ eyewear, safety glasses, and sports accessories like swimming goggles because of their durability.
Similar to high-index lenses, polycarbonate lenses have a high refractive index of around 1.59. This makes them ideal for low-to-high prescriptions, like the ones at Pair Eyewear.
High-Index vs. Polycarbonate Lenses: Which Is Better for You?
If you’re having a hard time deciding on high-index vs. polycarbonate lenses for your new pair of glasses, here are some key factors to consider.
High-index lenses are favored for stronger prescriptions, thanks to their high refractive index.
Generally speaking, eyeglass lenses with a higher index need less material to bend light. That’s why most opticians and optometrists recommend normal index lenses for low to moderate prescriptions. High-index lenses allow you to wear higher prescriptions without thick lenses that give you a “bug-eyed” look.
Polycarbonate lenses also score relatively high on the refractive index, so this lens material is good for strong prescriptions, too. But they’re especially useful if impact resistance is at the top of your list of needs.
Wearing glasses doesn't mean you need to think twice before signing up for soccer camp or kicking up your heels on the dance floor. With the right lens choice, you can ensure your spectacles withstand your most energetic activities.
That’s where Poly C lenses triumph in the high-index vs. polycarbonate debate.
Polycarbonate lenses are highly revered for their formidable impact-resistant properties. For context, these lenses can hold up to five times the impact of CR-39 lenses, which are pretty durable themselves.
When pitted against the more brittle high-index lenses, polycarbonate lenses are much less likely to break and shatter. That’s why most eyewear for kids (like the ones at Pair Eyewear) and sports are made with polycarbonate lenses.
When debating high-index vs. polycarbonate lenses, some may argue that one potential downside of the latter is their relatively low Abbe value of 30.
Abbe value refers to how well the lens disperses light. Lenses with lower Abbe values have higher dispersion, resulting in chromatic aberration. That means light rays of different wavelengths focus on different points when they pass through the lenses. This leads to unwanted color distortions — think rainbow-like glares around the lens’ edges.
For that reason, a high Abbe value is usually preferred if you want better visual clarity and comfort with your eyeglasses.
However, if you have your sights set on the impact resistance of polycarbonate lenses, you have options. Some manufacturers, like Pair Eyewear, have a workaround solution in the form of an anti-reflective coating to cut down on visual distortions.
Still, if you think you’ll be better off with high-index lenses, we'd like to point out that these lenses also typically have a low Abbe value of around 32 to 42.
Lightness and Thinness
High-index vs. polycarbonate lenses — which is lighter and thinner?
Strictly speaking, high-index lenses are thinner than polycarbonate ones. In fact, high-index plastic lenses are some of the thinnest lenses on the market.
The reason? High-index lenses are flat in the front and the back to achieve their high refractive index. For nearsighted prescriptions, the eyeglass manufacturer can flatten the lenses even more to make the center as thin as 1.5 millimeters without compromising their impact resistance. For reference, the lens thickness of standard CR-39 lenses is around 2.0 millimeters.
That said, thinner lenses don’t necessarily weigh less. High-index lens material is actually heavier than polycarbonate. So, if lightness is something you prioritize in your eyewear, a lightweight pair of polycarbonate glasses might be less likely to cut into your nose and ears.
You may have heard that glass lenses are the best at scratch-resistant protection and may extend the longevity of your eyewear. Unfortunately, this type of lens is also the most breakable and can be dangerous when shattered.
For safety purposes, it’s best to choose high-index plastic lenses, which are generally scratch-resistant. The plastic material is less likely to break upon contact.
Meanwhile, polycarbonate lenses are not very scratch-resistant. But that shouldn’t put you off them, given their impact resistance. You can always request an anti-scratch coating to protect your glasses.
Those on a budget may favor polycarbonate lenses over high-index ones.
The latter incurs higher costs during manufacturing. That's because high-index lenses need a greater degree of precision during cutting and grinding to create their distinctive curves. This, in turn, hikes up the prices for consumers like you.
On the other hand, polycarbonate lenses are much cheaper to produce, which means you pay less for the glasses. Case in point: Pair Eyewear’s frames start as low as $60, including the prescription lens options!
High-Index vs. Polycarbonate Lenses: The Choice Is Yours
There are various pros and cons for high-index and polycarbonate lenses that can help you determine the right fit for your next pair of glasses.
For instance, if you have a high prescription try high-index lenses for their thinness. That said, if you value lightness and durability, then polycarbonate lenses may be the wiser choice here.
No matter which type you end up with, high-index and polycarbonate lenses can be combined with an aspheric design to make the eyeglasses aesthetically thin. Those looking for UV protection may also be interested in transition lenses that darken in the presence of sunlight. And if you want to minimize the uncomfortable symptoms of computer vision syndrome (read: digital eye strain), opting for blue-light lenses may help.
For eyeglass wearers interested in polycarbonate lenses, Pair Eyewear will become your go-to brand in no time. We offer this lens type in single-vision and progressive lenses treated with an anti-reflective and anti-scratch treatment at no additional cost. If thinness is what you desire, our Premium Plus lenses boast 1.67 ultra-thin lenses made of lightweight glass. There are also our light-responsive lenses to protect your eyes from harmful UV rays.
And the best part? Our prices start as low as $60 with a huge collection of fun designs (aka our Top Frames) to suit everyone.