Technology advances seem to be everywhere these days, and the safety eyewear arena isn’t any different. Whether it is improved comfort or style, a broad range of shades and colours, and super light-weight designs, improvements in safety eyewear are being made. One of the newest innovations is transition safety eyewear (also called photochromic), which means it automatically adjusts from a clear lens to shaded lens when the wearer goes outdoors and back to clear again when they come indoors. This “automatic lens tint” feature eliminates the need to carry more than one pair of glasses for variable work settings.
The science behind this innovation is quite simple, when exposed to UV light trillions of silver halide or organic photochromic molecules in the lens change structure. The changed structure of these molecules absorb more visible light. The reaction to the presence of UV is fast with most lenses turning dark in less than 10 seconds. The lenses return to clear between 30 seconds and two minutes after going back inside and away from UV light. New technology is being developed that will speed the transition – we’ll keep you posted. Transition lenses may be made of glass, polycarbonate or other types of plastic, although not all of these are appropriate for safety glasses. A range of clear and dark transmittances are available. Lenses are available with a scratch resistant coating and block out 99.9% of harmful UV rays. Your Eyesafe optometrist can help you find the perfect fit for your job.
There are numerous benefits to wearing safety eyewear with transition lenses. This type of safety eyewear is typically not significantly more expensive and saves you from having to buy two pairs of safety glasses, one pair for indoors and one pair for outdoors. They are also more convenient because they save you from having to carry and keep track of two pairs of safety eyewear. Transition lenses do more than just function as sunglasses, they effectively filter out most of the harmful UV rays emitted from the sun, providing the necessary UV protection. Transition lenses come in a variety of shapes, styles, shades, and tints to meet all employees’ needs, tastes and sense of fashion. These lenses are also CSA compliant.
Before making the switch, there are few challenges related to transition lenses that you should consider. Different brands have different levels of darkness, different reaction times and in general they may not get as dark as you need them to be. Transition lens don’t work as well in very warm conditions. This so-called thermal effect is that complete darkening is not always possible in very hot work conditions. Conversely in very cold conditions the lenses will get very dark. This variability in performance may create an issue in some work settings. Use caution because using photochromatic lenses for safety glasses as inside work locations may be a problem in variable lighting conditions where a weak UV source is part of the light spectrum. They may cause temporary vision impairment when the light changes from bright to dim or vice-verse in the work area. Some of the older transition lens don’t work in vehicles, because they are UV activated and the glass windshield and windows absorbs most of the UV and so the lenses will not darken. There is new technology available where the transitions will work in vehicles. Be sure to ask your Eyesafe optometrist. Most transition lens are not polarized and so glare may remain a problem. As they age and wear out transition lenses may begin to develop a yellowish tinge when they’re not exposed to UV. This may or may not create an issue depending on indoor lighting conditions. As they age they may also be less responsive and will not darken, even in cold temperatures, to the same density they did when they were new.
Before deciding on the best option for safety eyewear review your work conditions thoughtfully consider the advantages and disadvantages of transition safety eyewear as part of any task hazard assessment or field level assessment work you do. Select your personal protective equipment carefully. Consulting with your Eyesafe professional about transitional lenses will provide important insights that may helpful in deciding what will work best for you. Finding your optimum safety eyewear choice may involve a lot of details and discussion, but it will provide for a safer and more comfortable outcome.
Glyn Jones is a partner at EHS Partnerships Ltd. in Calgary. He is a consulting occupational health and safety professional with more than 30 years of experience. He is a regular safety conference speaker in Canada and he provides program design and instructional support to the University of New Brunswick’s OHS certificate and diploma programs.