human
I'm a little confused about the different types of eyeglass lenses.
assistant
The most common type of lens is called a spherical lens, which is made up of two curved surfaces that are joined at the center. This type of lens focuses light in one direction only and can be used for both distance viewing and close-up work. A second type of lens is an aspheric lens, which has a slightly more complex shape than a spherical lens. Aspheric lenses have multiple curved surfaces that focus light in several directions, allowing them to provide better visual acuity when looking through the lens. A third type of lens is a multifocal lens, which combines two or more different types of lenses into one pair. These lenses allow you to see clearly from a greater distance and also offer good vision when reading or doing close work.