Progressive lenses have three sections: the upper part for far vision, the middle part for intermediate vision, and the lower part for near vision. Unlike bifocal and trifocal lenses, progressive lenses have no visible lines separating the sections, making them more aesthetically pleasing and comfortable to use. Progressive lenses are suitable for people who need different levels of correction for different distances.
Advantages of progressive lenses are that they provide seamless vision correction for near, intermediate, and distance vision, and that they have a more natural and aesthetic appearance than bifocals. Some disadvantages are that they are more expensive, require a longer adaptation period, and may cause some distortion or blurriness in the peripheral areas of the lenses.