Which of the following describes a one-piece bifocal?

A one-piece bifocal, also known as an executive bifocal, is characterized by its design that seamlessly integrates the distance and near vision portions without a visible line separating them, providing a continuous optical surface. This type of bifocal has a uniform width across the lens, making it easier for wearers to switch between different viewing distances without a noticeable jump.

The executive bifocal typically features an extensive reading area, which is ideal for tasks that require significant near vision, such as reading or detailed work. The design promotes a more comfortable and efficient transition between seeing far away and up close.

While segmented types, commonly referred to as straight-top bifocals, do feature a distinct line separating the two vision areas, the executive bifocal does not have this feature, emphasizing its one-piece nature. The flat-top bifocal also includes a horizontal line, defining it as a segmented style. Trifocals, on the other hand, incorporate an additional segment for intermediate vision, rather than focusing strictly on the bifocal aspect. Thus, the executive bifocal stands out as the best choice for describing a one-piece bifocal due to its continuous and integrated design.