What Does High Index Mean?

Every eyeglass lens has a measurement called the refractive index which indicates how much the material will bend light which enters it. In other words, it’s the ratio between the speed of light through air and the speed of light through whatever material your lenses might be.


The higher your index, the more light is refracted and bent as it goes through the lens. This also means that if you have a high index lens, you can increase your prescription as well without drastically increasing the weight of your eyewear. However, higher index lenses tend to be more expensive.


Finally, the refractive index of your lenses will also directly affect the reflectance of them. The reflectance is the percentage of light reflected off a surface, and the higher the refractive index, the greater the reflectance.


Now that you know how the index will affect your prescription eyewear, you can go to Lensabl.com and check out our selection of lens types, including high index lenses.

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