Brief Course Description
Rx Sunwear Rimless Eyewear
This course starts with a presentation of the potentially adverse effects of
ultraviolet radiation (UV) on the eyes and then identifies ways to protect the visual
system from over exposure to UV. It goes on to include a brief presentation of the
electromagnetic spectrum and illustrates where ultraviolet, visible light, and infrared fit
in to the overall spectrum. The subject of tints, coatings, density designations for
plastic and glass lenses, is covered.
Photochromic lenses have always been about change, starting with the first
photochromic lenses that were invented back in the 1960’s. Then, as now, the primary
motivation behind photochromic lenses was to produce a lens that was clear indoors and
would darken automatically into an effective sunglass when the wearer went outside.
Photochromic technology began with glass. Consumer fascination with the earliest
glass photochromic lenses occurred just as CR-39® lenses had begun gaining
momentum. However, it would take the industry another 30 years to develop a
commercially viable plastic photochromic lens. Today, years after the introduction of
the first commercially viable plastic photochromic lenses, the various technologies that
give lenses their photochromic characteristics continue to evolve.
Polarized lenses have become one of the fastest growing lens categories for
prescription sunwear in recent years. In fact, many ophthalmic professionals and their
patients feel that polarized lenses are the best sunglasses available due to their ability to
dramatically reduce glare. And new manufacturing techniques have significantly
improved the products which are now available on the market.
First introduced in the 1930s, polarized lenses are now available in a variety of lens
materials, styles and prescription ranges which include plano, flat-top bifocals and
trifocals, and progressives. And lens materials available in polarization include CR 39,
high index 1.56, polycarbonate, photochromic plastic, and photochromic glass.
Frames requiring lenses with steeper than usual base curves, also known as “wrap”
eyewear, have become popular as sunglasses in recent years. Here, in the concluding
section of this course, we discuss the potential optical problems and possible solutions
that can be created when steeper than usual base curves are used.