Referred to as no-line bifocals or trifocals, progressive glasses are ideal for patients who have presbyopia vision condition marked by a decrease in the ability to focus sharply on nearby objects.
progressive lenses are the latest development in meeting the needs of people who require both near and far vision correction. Progressive lenses eliminate the traditional lines in a pair of bifocal or trifocal lenses. Unlike bifocals and trifocals, progressive lenses don't have a sharply defined boundary between near and far parts of the lens. It's the midpoint between the two where progressive lenses can have the greatest effect, as in traditional bifocals, that area is right on the dividing line.
As we age naturally, our ability to see nearby objects and objects in the distance can decrease. Progressive lenses address separate visual needs in one lens usually with a distance viewing field build into the upper portion of the lens, and a near vision field built into the lower portion.
Unlike traditional bifocals or trifocals, there are no visible lines separating the different fields of a progressive lens. Your eyes are seen clearly behind the progressive eyeglasses, you have got the same look as eyeglass wearers often half your age, and there are no lens lines to distract your vision.
Bifocals and trifocals make it obvious that the patient has reached a certain age and requires additional help to read and see. Progressive lenses eliminate that obvious line and look just like regular glasses. Aside from the cosmetic advantages, progressive lenses can actually provide a more natural correction of presbyopia (not being able to see things close up, which occurs with age). The seamless transition allows the wearer to adjust quickly to close, middle and far distances without adjusting the head and neck to get just the right angle for bifocals.
Conventional bifocal and trifocal lenses are made in two different ways. Lenses are made of either plastic or glass, both of which are originally in liquid form; the lenses are poured into a mold (cast) and then allowed to harden. In some cases, the bifocal or trifocal parts are embedded into regular lenses when they are poured. In others, the lens is actually cast in a different shape to provide the necessary visual adjustment. Progressive lenses must be custom-shaped according to the wearer's prescription requirements and may require more testing to assure quality and correctness. In all other respects, progressive lenses look and function just like bifocal or trifocal lenses.