<human>: I'm a little confused about the different types of eyeglass lenses.
<bot>: The three main types of lens are single vision, bifocal and progressive. Single vision is a single lens that provides clear vision for distance and near objects. Bifocal lenses have two different optical powers in one lens, allowing you to see both near and far objects. Progressive lenses are designed with many layers of different refractive power, providing clear vision from distant to near objects.