Eyeglass lenses correct refractive errors within the eyes. When choosing lenses keep in mind that the higher the refractive index, the thinner the lens. Why? The index of refraction of the lens material determines the light-bending ability (lens power) of eyeglass lenses and is the ratio of the speed of light when it travels through air to the speed of light when it passes through the lens material. The speed of light is reduced when it is refracted as it passes through a lens material. Lenses that bend light more efficiently have a higher index of refraction and are therefore thinner. The lens power that you need to ensure high-quality vision is indicated on the eyeglass prescription from your eye doctor. The lens power to correct refractive errors in the eyes is measured in diopters (D). If you are nearsighted the value is negative (thinner in the center and thicker at the edge) and farsighted it is positive (thicker in the center and thinner at the edge).
If you want thinner and lighter lenses that are attractive and comfortable choose high-index eyeglass lenses. High-index lenses (lens material with a refractive index that's higher than that of glass i.e. 1.523) are particularly suggested if you have a strong eyeglass prescription for astigmatism, farsightedness or nearsightedness. The stronger the prescription for nearsightedness the thicker the lens edges as mentioned before. The edges of the lens are most visible, and when thick, can detract from the look of your eyewear. With trendy frames made of plastic and metal, the rim is thinner than the lens and with popular rimless frames the lens edges are completely exposed.
Some of our lenses come standard with UV400 protection which is the highest level of protection your lens can have since it blocks 100% of all harmful light from the sun (These lenses block light rays with wavelengths up to 400 nanometers, so your eyes are shielded from even the tiniest UV rays.)