What is the lens index?

The lens index (refractive index) indicates the bending of a ray of light when passing through an optical environment (eyeglass lens). The smaller the index, the less you feel the chromatic aberration or distortions at the edges of the eyeglass lens.
Lenses with an index of 1.5, 1.6, 1.67 and 1.74 are available in our online shop. 1.5 and 1.6 lens indexes are the most common and there is little to no distortion. In the case of 1.67 and 1.74 index lenses, distortions may occur with larger frames.
The thickness of the eyeglass lenses is often also mentioned when talking about the lens index. An index of 1.5 is called the base index. A 1.6 index lens is usually 30% thinner and 20% lighter than a base index lens. A lens index of 1.67 means a lens 40% thinner and 30% lighter than a base index lens, and a 1.74 index lens is up to 50% thinner and 30% lighter.