Progressive lenses, also called progressive addition lenses (PALS), invisible or no-line bifocals, help you see in the distance, up close and in between. Unlike bifocals with lines, progressive lenses do not have a blurry area caused by the line, but they have a corridor or "channel" you look down through from distance vision to near vision. More expensive lenses have longer, wider or technically advanced corridors. Different progressive styles work in different ways. Understanding premium progressive features helps you choose the right style of progressive lens for your needs.
Wide Distance Viewing
Dr. James Sheedy, director of Vision Ergonomics Laboratory, conducted a study on 28 different progressive designs and their viewing zones. His study, published in the February 2004 issue Optometry Journal, picked the top five progressive lenses with the widest range of viewing in the distance: Younger Optical Image, Sola's progressive called Percepta, Super No-line by Essilor, Shamir's Genesis and Vision Ease's Outlook. A wider distance viewing area in a premium progressive is beneficial for people who do a majority of their work in the distance, such as driving or teaching.
Wide Corridor Lenses
Dr. Sheedy's study determined the top five widest corridor or intermediate viewing areas: Johnson and Johnson's Definity, Pentax AF Mini, Zeiss Gradal Top Progressive, American Optical's Pro 15 and SOLAMax Progressive Lens. A wider intermediate corridor and viewing area are important for people who do more work at arm's length or further, for instance, working on a computer or cash register or reading blueprints on a desk.
Customised Progressive Lenses
One of the newest technologies available is the premium progressive lens, which is individually designed based on a patient's prescription and physiological behaviour and on head and eye movement. The Varilux Ipseo by Essilor uses a premium progressive design based on individual visual ergonomics. The idea behind this type of lens is that the more the eye moves, a wider viewing zone benefits the patient. The more a patient's head moves, a narrower bifocal zone with less side distortion works better.
Other customised lenses include the Shamir Telegraph, Rodenstock's Multigressive ILT, the Genesis 1, Seiko's Super P1 and Hoya Optical's Hoyalux id. Zeiss Optical's Gradal Individual progressive lens is another customised lens designed with special convex curves based on an person's individual prescription.