In what way do progressive addition lenses differ from traditional bifocals?

Progressive addition lenses are designed to provide a seamless progression of lens power from distance vision at the top to intermediate and near vision at the bottom without any visible lines or segments. This gradual transition allows users to experience a more natural visual flow as they move their gaze from different distances.

In contrast, traditional bifocals feature distinct, separated segments for distance and near vision. This separation results in a sudden change in lens power, which can be jarring for the wearer. The smooth gradient of progressive lenses not only enhances comfort but also broadens the field of usable vision, accommodating various visual needs without the abrupt shifts that characterize bifocal lenses.

The other options do not accurately represent the main differences. For instance, while progressive lenses may sometimes be more expensive due to their complexity and technology, affordability does not reflect a fundamental characteristic of these lenses compared to bifocals. Additionally, materials and designs for progressive and bifocal lenses can both be commonly found, so the notion that progressive lenses are more difficult to find isn't a valid differentiator.