Hi-Index lenses

Consumer desire for even thinner and lighter lenses—to avoid the “bug eye” look and to prevent heavy glasses from sliding down the wearer’s nose — lead to the development and production of high index lenses. These lenses have a refractive index of 1.67 or 1.74. For a little perspective, high index lenses with a refractive index of 1.74 are about 50% thinner than CR-39 lenses. Like polycarbonate lenses, high index lenses block 100% of UV rays.

So now let’s talk more about the refractive index, which is what defines the “high index” of high index lenses. Often, our vision problems are caused by refractive errors, meaning the light does not travel through our eyes the way that it is supposed to. Corrective lenses do some of the work of bending light for our eyes. The refractive index defines how light moves through a material, and lenses made from material with a high index refract light more efficiently, meaning “less material can be used in high-index lenses to correct the same amount of refractive error, which makes high-index plastic lenses both thinner and lighter than conventional glass or plastic lenses.”

There are a few drawbacks to high index lenses — they are more expensive and have a lower Abbe value, meaning there might be a very slight decrease in clarity of objects seen at particular angles. However, for many people, high index lenses offer far more benefits than drawbacks.

According to AllAboutVision.Com, an independent informational website devoted to providing consumers with unbiased information, high index lenses are especially beneficial for people who suffer from hyperopia (farsightedness). If your prescription is above a +1.00, you may be a good candidate for high index lenses, and whether you should choose 1.67 or 1.74 high index lenseswill depend on the strength of your prescription. Certain types of frames may also be more suited to thinner lenses.

If you have questions about what type of lenses are right for you, make an appointment to talk to your eye care professional. In the meantime, you can download this free e-book or visit highindexlenses.com, where you can read a variety of informational articles or live chat with an expert.