Mineral Glass lens with Round bifocal and Flat top bifocal. Can use long time than plastic lens.
Mineral spectacle lenses are lenses made of colorless and colored inorganic glass.
Benefits of mineral spectacle lenses for the wearer
* They have high and stable optical properties. * Resistant to scratches compared to organic eyeglass lenses. * A wide range of are available in the form of tinted, sun-protection lenses, including those with a fashionable mirror coating, as well as photochromic. * Optical coatings have better adhesion to the surface of mineral spectacle lenses. * High refractive index spectacle lenses solve the problem of thick spectacle lenses. The lenticular and aspherical surface design makes these spectacle lenses thinner, flatter, lighter. 
