Are High Index Lenses Right for Your Next Pair of Eyeglasses?
Every time you go to your optometrist and get an updated prescription, it’s time to get a new pair of eyeglasses. While it may be strange to switch away from your old pair, each new prescription is an opportunity to reinvent your entire glasses wearing experience. You can try a new look with the frames, try a new lens coating or even an entirely new lens design! Considering each new change can be fun on its own but the ultimate goal is always to find the right glasses configuration that works best for you. It’s up to you to determine whether or not your vision needs and lifestyle suit each decision and settle on the perfect set of features. You’ve tried out the different shapes of frames to see how they suit your face, considered the difference between Polycarbonate, Trivex, and real glass lenses, and experimented with lens coatings like anti-reflective or anti-fog… but what about high index lenses?
What are High Index Lenses?
Just in case you haven’t heard of them yet, high index lenses are the new craze in eyeglasses technology. In short, high index lenses are thinner than traditional lenses, but why is the really interesting part. Lens crafting has been a developing science for over 800 years but only in the last 40 have we been able to significantly improve the process. The first pair of high index lenses were invented by accident in 1983 when a lens crafting company made a new incredibly durable plastic lens material known as polycarbonate. Meant to keep people safe from eyeglasses shattering on impact, they were also denser than traditional plastic lenses.
As it turns out, that density changed something barely we had barely noticed before: the index of refraction which is how tightly light bends when it passes through the lenses. For polycarbonate lenses, the light passed through at a sharper angle (more efficiently) meaning that they needed thinner lenses to achieve the same prescription correction. These were the first high index lenses. By the numbers, normal lenses have a refraction index of 1.50 and polycarbonate lenses had an unprecedented 1.59 index. Since then, newer and more advanced plastics have been designed to provide even higher indexes with the highest up at 1.74 which are a full 35% thinner than standard lenses.
Why High Index Lenses are Awesome
Now that you understand where high index lenses came from and what the index means, you may be wondering why people are going crazy for this new lens technology. What’s so special about high index lenses? Among the multiple benefits, the primary difference is that high index lenses are much thinner than normal lenses allowing people with very strong prescriptions to see life through less material. In addition, high index lenses also reduce the amount of eye distortion and have an increased visual clarity.
When it comes to lens crafting, the intensity of your prescription determines the amount you need light to bend to correct your vision. The more light bending is needed, the thicker your lenses need to be. This means that for anyone with a strong prescription, lenses can get pretty thick. This may not seem like a big deal until it comes time to choose frames, or worse, be seen through your glasses. Because high index lenses are more efficient at bending light due to their increased density, less material is needed to achieve the same vision correction. Polycarbonate 1.59 is a full 20% thinner but they go all the way up to 1.74 at 35% thinner depending on your needs, budget, and preferences.
Less Eye Distortion
We’re all familiar with the cartoons who put on glasses and suddenly their eyes look huge. This is called eye distortion and it can also go the other way, making eyes look smaller than they really are as well. Eye distortion is what happens when people look at your eyes through your glasses. The thicker the lenses are, the more eye distortion you have to deal with. It can change the apparent shape of your face and even make it difficult for people to effectively meet your eyes because they’re not quite in the right place like how a drinking straw looks distorted once it goes into the water. Because high index lenses are thinner, they create much less eye distortion for people with traditionally thick lenses.
The visual clarity of a pair of lenses can be determined by how clearly you see the world around you. Smudges, scratches, and light aberrations all interfere with visual clarity. While smudges and scratches are determined by care, high index lenses significantly reduce the number of light aberrations (random prism-like bands of color) in your lenses. This improves your visual clarity and decreases the chances that you might be distracted by a random beam of light through your glasses.
Are High Index Lenses Right for You?
We’ve spent some time explaining high index lenses and extolling their virtues, but of course, the truly important question is whether they’re the right choice for your next pair of eyeglasses. The first question you should ask yourself is whether or not you care about lens thickness. Many people struggle with their lens thickness and wish for thinner lenses for a variety of reasons. Some people like slender metal frames which tend to look silly with wide flaring lens edges. Others have a bigger problem with eye distortion and wish their lenses were thinner so that their eyes could be more clearly seen through the glasses. If lens thickness is your personal bane, high index lenses could be the perfect solution.
The next question is what your actual prescription is. Oddly enough, high index lenses are best when used with high absolute value prescriptions that result in thick lenses. If your prescription is too mild, the lenses will become thinner than is practical to secure into frames. Most prescriptions are fine with polycarbonate lenses and an index of 1.59 but if your prescription is not higher than +3.0 or lower than -3.0 then you probably don’t need a higher index. However, the more extreme your prescription, the higher an index you can safely choose.
Finally, it’s time to check your budget. Because high index lens materials are specialized and somewhat more advanced than normal plastic lenses, they also tend to be a little more expensive. This can range from an extra $10 to $300 to it’s important to be apprised of the difference so you know what you’re ordering and what to expect on the bill.
Are high index lenses right for you? Now that you know the basics, it’s time to speak to your optometrist and optician about new options for your eyeglasses. They will be able to help you with the rest of the details like choosing the exact right index for your prescription, selecting a lens material in your price range, and finding frames that will flatter your new look with much thinner lenses. In all the excitement, don’t forget the lens coatings. High index lenses should always be paired with anti-reflective coating but you should also consider anti-fog, UV protection, and transition shades to give your glasses ultimate utility. With high index lenses, your next pair of eyeglasses could literally change the way you look at the world.