What are Progressive Lenses?
Progressive lenses, also called progressive addition lenses (PAL) or varifocal lenses, are corrective lenses used in eyeglasses to correct Presbyopia . Unlike bi-focals, which have only two focal points (distance and reading), Progressive lenses have three focal points, distance, reading and intermediate. The intermediate zone is very helpful for computer reading and reading other materials at a similar distance. The top part of a Progressive lens is used for viewing distance objects, the middle part for computer work and other work at a similar distance, and the bottom part of the lens is used for reading near vision objects, like books, newspapers and cell phones. Progressive addition lenses avoid the discontinuities (image-jumps) in the visual field created by bifocal and trifocal lenses and make reading a far more comfortable experience. Also, because of the absence of the line found in bifocal lenses, progressive lenses are more cosmetically attractive. Since bifocal and related designs are associated with 'old age', proponents have suggested the lack of segments on the lens surface of a progressive lens appears more 'youthful' since lenses associated with younger wearers [single vision] lenses tend to be free of segments or lines on the surface. |
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