What type of lens configuration is described as having two segments that are 13-14mm apart, one at the top and one at the bottom?

The description of having two segments located 13-14mm apart, with one segment positioned at the top and the other at the bottom, accurately portrays a lens configuration known as a multifocal with a double segmented lens. This type of lens provides distinct vision zones for different viewing distances, typically allowing for both distance and near vision corrections.

In this configuration, the two distinct segments aid the wearer in transitioning between viewing tasks, making it suitable for individuals who require correction for both distance and near vision without the gradual change seen in progressive lenses. The specific placement of segments, at both the top and bottom, implies that the lens is designed to facilitate relatively quick shifts in focus, distinguishing it from other lens types.

In contrast, bifocal lenses feature only two segments and usually have a more defined line between them, while single vision lenses are tailored for a single field of vision. Progressive lenses smoothly transition between multiple prescription strengths but do not have distinct segments. Thus, the specified configuration directly aligns with the characteristics of a multifocal with a double segmented lens.