Types of spectacle lenses: According to the material: - organic: CR-39 lenses, Trivex lenses, nxt lenses, polycarbonate lenses; - mineral. According to the optical effect: - afocal; - astigmatic; - Stigmatic. By the position of the main focus: - negative; - Positive. According to the number of optical zones: - progressive; - multifocal; - four-focal; - three-focal; - bifocal; - varifocal; - Transfocal. According to the index of refraction: - traditional (ne - 1,50 -1,52); - with an average value (ne - 1,52 -1,59); - high-refractive (ne from 1.59); - superhigh-refracting (ne from 1.74). According to the shape of the refractive surfaces: - Lenticular; - aspherical; - spherical. On optical coatings: - water and dirt repellent; - hardening; - multifunctional; - enlightening; - Mirror. On the effect on the intensity and properties of the light flux: - photochromic; - Color. According to the protective effect: - polarizing; - the excess brightness of various radiation sources; - from chemical effects; - from mechanical impact.