When Your Prescription is “High Enough” to Consider High Index Lenses
High index lenses are some of the highest quality lenses you can order. They are appropriate for most prescriptions, depending on what you want out of your lenses, but there are some prescriptions that simply don’t warrant high index.
“High Enough” to Consider High Index Lenses
If you can see well without glasses, for instance, you are probably better off getting a less expensive lens material as the difference in thickness and weight will be almost nonexistent and, in a few ways, your optics will be better. High index plastic is often assumed to be reserved for those with prescriptions so high they can see no more than blurry shapes when they take their glasses off, but this isn’t the case. Many people order high index nowadays simply because they look better, or because their doctor recommends them. Here are a few things to consider about prescription strength and high index lenses:
- If your prescription is below +1.00 or above -2.00 (combined sphere and cylinder, per eye), you will not notice much of a difference between high index plastic and standard plastic.
- If your prescription is stronger than the above specifications, you will see a noticeable difference in thickness of your lenses and, as prescriptions get stronger, a noticeable weight difference becomes apparent as well.
- High index plastic has a low Abbe number, or a high amount of color aberration. This means that high index lenses cause colors and light to “rainbow,” much as a crystal will do to sunlight. The result, especially when lenses are thicker and in your peripheral vision, is some blurring or distortion, leading to poor optics. Standard plastic does not do this nearly as much and is therefore better than high index when your prescription is light.
- High index lenses also tend to reflect more light than standard lenses due to their high density. This is another reason for avoiding them if they are not necessary; high index lenses require anti-reflective coating to avoid distracting and vision-compromising glare.
- When your prescription is not very strong but still above the previously listed specifications, you will be happy with the difference that high index lenses make. They will be lighter, thinner, and more aesthetically pleasing, and they will mask the strength of your prescription.
- High index lens material should be avoided if you are looking for impact resistance. If your prescription is not too high for a wraparound frame, and you are getting glasses for safety, riding a motorcycle, or some other activity that requires impact resistance, it is a good idea to go with polycarbonate. It is the most impact-resistant lens material available today.
High index lenses are a great choice when your prescription is high enough, but their cost, high glare, and low Abbe number make them a poor choice for weak prescriptions. There are few lenses which match the versatility of high index, with their thinness, light weight, scratch resistance, and aesthetics, but that does not mean that they are right for everybody. If your eye doctor has recommended a lens material to you, then the choice should be simple. If you are working on deciding whether high index lenses are right for you and this article has not been enough for you to make a decision, take a look at some of our other articles to learn more about high index. Thanks for reading, and happy shopping!