Bifocal lenses are a type of multi-focal lens — one that has more than one point of focus.
Therefore, for those who need glasses for both reading and distance, bifocals seems to offer an attractive alternative.
Unlike single-vision lenses, bifocals have two viewing regions, each with a different correcting power, marked by a visible separating line. The larger upper portion of these lenses are meant for distance vision, while a smaller segment below is meant for reading.
Therefore in order to clearly see distant objects, the wearer of the bifocals would need to look straight through the lenses (through the upper distant vision region), while reading a book would require them to adjust the tilt of their head, and the book placement such that the book would be visible through the bottom near-vision segment of the lens.
As the patient’s eyes glide from one region to the other, crossing the separation line, there is a noticeable and abrupt change in the lens power. Thus, it takes first-time wearers of these glasses some time to get accustomed to bifocals, as they learn how to best move their eyes between the reading and the distance sections of the lens.
If you need corrective power at both near and distance, but don’t want bifocals due to their visible separation line, consider progressive lenses explained further below.
If you need corrective power at both near and intermediate distances –for example for both reading and computer use –you might want to consider workspace progressive lenses. See the appropriate section below.
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