The first photochromic lenses appeared in 1964, and quickly drew interest for their unique ability to darken in sunlight and fade back indoors. However, the first generation of photochromic lenses came with cosmetic and functional barriers – two of the largest being that it took them about an hour to fade and they never got fully clear.
Fast forward more than half a century, and the technology has greatly expanded, as have the types of light-reactive lenses available. Reaction speeds, darkness, clarity, and overall aesthetics have all improved greatly, and there are now four different types of light-reactive lenses available: standard, extra reactive, ultra-fast, and polarized.
In part one of this three-part series, we’ll be focusing on standard photochromics, with an emphasis on the technology, benefits, ideal patient, performance expectations, and dispensing. Read through each or jump to a section by clicking one of the buttons below:
Standard Photochromics: The One that Started it All
Standard photochromics are the original offering in the light-reactive lens category. But, unlike their slower, unsightly predecessors, today’s options have made huge strides in both performance and appearance. Like all light-reactive lenses, standard photochromic lenses provide a variety of great benefits for almost any patient.
But, before we dive into the advances and benefits, let's take a quick look at how standard photochromics work.
How Do Standard Photochromic Lenses Work?
Dye molecules in the lens change structure when UV light strikes them. When UV light is present, the molecules “unfold,” absorbing light and appearing colorful. When the molecules are removed from UV light, they fold back, appearing colorless.
What Are the Benefits of Standard Photochromic Lenses?
While they don’t share all the technological advancements of their extra reactive and ultra-fast brethren, standard light-reactive lenses still provide a long list of great benefits:
Who's the Ideal Patient for a Standard Photochromic Lens?
Identifying an ideal candidate for a standard light-reactive lens comes down to getting to know your patient a little more personally. Things you’ll want to consider when determining whether a patient is a photochromic fit, include, but aren't limited to occupation, lifestyle, and location:
Jobs that entail shifting from indoors to extended periods outdoors are great fits because they don’t necessarily require ultra-fast fade-back speed. But, don’t limit your options to outdoor professions. Some examples of occupations that lend themselves to standard light-reactive lenses include:
Lifestyle activities that require a lens built for indoor and outdoor use without the need for ultra-fast fade-back speed benefit from a standard photochromic. Some possible light-reactive lifestyles include:
Areas where UV levels are at their peak are prime locations for a lens built to respond to ultraviolet rays. These areas include:
Related Content: 8 Factors that Increase Your UV Exposure (Infographic)
Setting Realistic Expectations Around Standard Photochromic Lenses
Setting realistic expectations about performance sets the stage for a better wearer experience. When it comes to standard light-reactive lenses, here are a few points to mention:
Visual Experience: Many people choose a light-reactive lens thinking they perform like a pair of sunglasses. While they do darken outdoors and provide relief from bright light, the view looking out is quite different. The view through a photochromic is not as dark as a pair of sunglasses. In fact, it feels more like looking through a standard pair of glasses than a dark pair of prescription suns. This is actually beneficial to the wearer as it provides exceptional visual precision and contrast in addition to outdoor comfort.
Fade-Back Speed: Standard light-reactive lenses can take anywhere from seven to 20 minutes to return to clear. Ambient temperature can speed up and slow down fade-back speed, with hotter temperatures resulting in faster fade back and colder temperatures yielding longer lag time from dark to clear.
Outdoor Darkness: Because light-reactive lenses work in direct response to UV exposure, factors that decrease the amount of UV reaching the lens can impact how dark they get outdoors. Examples include:
In-Car Performance: Because standard light-reactive lenses respond only to UV light and most car windows have UV filtration embedded in the windows, these lenses generally won’t work in cars.
Related Content: 12 Ways Light-Reactive Lenses Respond to their Environment
Tips for Dispensing Standard Photochromic Lenses
Related Content: 4 Simple Tips for Picking the Perfect Frame for a Photochromic Lens
Wrapping it Up
If ultra-fast fade-back speed and in-car activation aren’t must-haves for your patient, standard light-reactive lenses represent a good value, providing all the other benefits of the light-reactive category.
Be sure to read part two in our three-part series: The Optician's Ultimate Guide to Extra Reactive Photochromic Lenses
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