Progressive lenses are lenses used to correct vision which offer a gradation across the lens which provides several degrees of magnification. These lenses are classically prescribed to older adults who have presbyopia. Historically, older adults required bifocal or even trifocal lenses for vision correction. These lenses could be uncomfortable to wear, not least because the distinctly different zones of magnification caused image jumps. With progressive lenses, there are no lines and no clearly demarcated zones, making for much smoother vision.
Progressive lenses are available in the form of both glasses and contacts. In both cases, the area of lightest magnification is at the top of the lens, with the magnification becoming stronger at the bottom of the lens. The one drawback is that the sides of the lenses tend to be somewhat distorted, which can be disconcerting when looking out the corner of the eye.
Adjusting to progressive lenses can take some time, whether one is switching from single lenses or a pair of bifocal lenses. Some people feel dizzy, nauseous, or disoriented for the first few days while they settle in. Some optometrists recommend wearing new lenses for only a few hours at a time at first, allowing patients to get used to the feel of the new lenses gradually. Wearers of progressive lenses also need to learn about how to exploit the lenses, finding the sweet spots in various areas of the lens which provide the crispest vision for different tasks.
Fit is critical with progressive lenses. While regular lenses can seem slightly disorienting or annoying if they don't fit well or are the wrong size, progressive lenses can be largely useless if they are not well fitted. When a new pair of progressive lenses arrives, the optometrist should take the time to confirm that they fit properly, and that the wearer feels comfortable. It's also important to take fit measurements before the lenses are ordered, and in the case of glasses, to select appropriate frames which will fit the face well and accommodate lenses of an adequate size.
These lenses are also known as graduated lenses, PALs, no-line bifocals, or varifocal lenses. There are some alternatives to progressive lenses for people who prefer not to wear them. One option is to use several pairs of single lenses, with a pair of basic day to day glasses and a pair of reading glasses which can be changed as needed. Another option is to use traditional bifocal or trifocal lenses.