An eyeglass lens having a smooth transition between parts with different focal lengths, correcting for vision at all distances.
- ‘A small segment with a stronger curve may be placed in the mold to form the segment for bifocals or progressive lenses.’
- ‘Bifocals have been on their way out ever since the invention of progressive lenses, which gradually change the visual viewing area for distance and reading.’
- ‘Among those given progressive lenses, vision deteriorated at only half the rate of the other kids.’
- ‘Trifocals can have visible lines or progressive lenses.’