Polarized lenses are one of the few premium eyewear products that can benefit almost any patient. More than just blocking the sun, polarized lenses are true performance products that eliminate glare, and, dependent on the tint, can enhance colors and contrasts.
Much has changed since the early days of polarized lenses, when the polarizing film was glued between two glass wafers. The lenses were available in single-vision only and the color choices were gray and brown. The latest generation of polarized plastic lenses includes a wide array of lens design choices and lens material and color combinations.
A patient’s basic optical needs can often be served with standard plastic, the most economical choice. If a reduction in lens thickness is required, select a 1.56 or 1.60 index, or a 1.67 index from Optima or Specialty Lens. These high-index lenses are designed with the film placed very close to the front surface so minimum thicknesses of slightly over a millimeter can be achieved.
If safety is a concern, there are many polarized polycarbonate lenses to choose from. (At present, there are no polarized lenses made from PPG’s impact-resistant Trivex material).
Polarized lens manufacturers produce a broad range of prescription lenses including single-vision, bifocals, trifocals and several progressive designs. There are also eight-base polarized lenses available for the popular wrap sunglasses. Some lens manufacturers offer customized polarized lenses that use aspheric designs to compensate for perceived power changes (i.e. reduced acuity in the periphery or change in magnification on higher minus Rxs) that occur when grinding a prescription calling for a flatter base on an eight-base.
A useful addition to any polarized sunglass is a backside anti-reflective coating, especially if there are base curve deviations. Applying a backside AR coating will eliminate any reflections resulting from the curves on the inside surface of the dark lenses, causing distracting glare.
Probably the most beneficial improvement in polarized product is the continual addition of task-enhancing and fashion colors. Performance eyewear and lens treatment manufacturers have researched the visual requirements of each activity in order to develop effective, ophthamically correct lenses. Each color can answer specific performance needs.
Grays are general purpose colors, because they are the most color-neutral. The darker shades are often recommended for deep water fishing. The lighter shades can be tinted over to create custom colors.
Tinting polarized lenses does not change the amount of polarization. If you start out with a lens that provides 50 percent polarization, that number will stay the same if the lens is tinted to 80 percent density.
Another benefit of the lighter colors is that they can be worn indoors. Computer users often suffer discomfort from glare reflected off the monitor screen. A lightly tinted polarized lens can minimize this problem.
Brown polarized lenses provide high contrast for activities such as driving, fishing, winter sports and golf. Polarized melanin lenses, available from Specialty Lens and Vision-Ease, not only provide high contrast for many outdoor activities but also provide protection against the damage done by exposure of the eye to the solar radiation that can affect cataract development and macular degeneration.
Yellow lenses transmit the most light and are favored by hunters. Yellow is most helpful on overcast days and for night driving.
Other polarized color options are red, blue, violet, orange and green. There is even photochromic polarized product and mirrored front surfaces.
In order to effectively present polarized lenses to your patients or customers, it is important that the office staff have a complete understanding of polarized performance. A useful tool is “The Art and Science of Polarization,” an education booklet produced by Younger Optics that explains, clearly, the effects, need and benefits of polarized lenses. (See sidebar, “How Polarized Lenses Work.”)
In the Melville, N.Y. office of John Viviani, OD, optician Steve DaParma, FNAO explains, “We are all committed to dispensing polarized lenses. I get a lot of support from the doctors. They often initiate the discussion of the need for sun protection with the patients.” DaParma does a lot to make the patients comfortable with their decision to choose polarized product. After teaching them about the features, he reinforces the decision by saying, “It’s not what the lenses cost. It’s what they’re worth in the way they repay you.”