The lens treatment that’s right for your job. Managing lighting levels and glare, inside and out.

Technological advances in terms of style and fashion have made having the newest and coolest safety eyewear both functional and easier to wear. A major change has been the advances in lens tints, colour and coatings for safety eyewear. The seemingly endless options make it much easier to ensure safety performance while taking advantage of the current trends.

Lens Tints and Colours

There is a broad range of lens tints and colours available that also now come with super light-weight design improvements in wearer comfort. Both the lens tint and lens colour can impact glare, along with the recognition of colour variations and contrast. The selection of the right lens for your safety eyewear can be helpful to control these exposures. Understanding light exposure is important in choosing the right lens colour and tint to optimize performance and wearer comfort. Too much white light can impact vision, and IR and UV can be harmful to the eyes. The lens tint and lens colour of safety eyewear can help to optimize performance, provide better visibility and clarity, and increase wearer comfort.

Lens tints are measured by the amount of light they let pass through the lens.  This is known as visible light transmission (VLT). A high VLT means a large percentage of the incoming light is transmitted through the lens and reaches the eye. The choices of lens tints range from clear lens (VLT of more than 85%) to very dark lens (VLT 5-10%). A standard pair of sunglasses has a VLT of around 20-40%.

The range of available lens colours is extensive across the visible spectrum from red to blue. Grey lenses are the most common colour for general use,  allowing for the most accurate colour visibility, plus the available range of VLTs allow for use in most applications. The other lens colours typically found in safety eyewear are listed below with a short description:

• Amber or yellow lenses block the blue end of the light spectrum and greatly improve contrast in low light. These would be good to wear in low light when the work being completed requires detail.
• Dark amber (sometimes seen as copper-coloured or even brown) lenses block blue light and glare and allow for improved visual contrast.
• Green lenses are less common but are associated with preserving colour balance and providing a slight improvement in contrast.
• Dark orange lenses increase contrast. Such a lens might be used when doing indoor inspections that require detail.
• Red lenses increase depth perception and allow for better recognition of details.
• Blue lenses reduce the yellow glare associated with sodium vapour lighting as might be found in some large older warehouse operations.

Lens Coatings

Early advancements in lens coatings and specialized treatments included mirrored and polarized lenses. Mirrored lenses have a coating on the outside of the lens which reflects much of the light otherwise coming through and this reduces glare and makes everything seem darker. Mirrored coatings are best used with a lower VLT lens tint.

Polarized lenses dampen out the glare of reflected light that may cause eye fatigue. Glare from light reflected off water or snow and ice is most common.  This dampening effect of a polarized lens can be a great advantage unless of course there is a need to be able to reconcile these reflected surfaces allowing you see them more specifically.

A popular advancement in safety eyewear technology is the use of  transitions lenses. Known technically as photochromic lenses, the lens tint automatically adjusts from a clear lens to shaded lens when the wearer goes outdoors and back to clear again when they come indoors. Photochromic or photo-greying lenses automatically darken as natural lighting levels increase. The lens reacts to the UV light in sunlight. The benefit of this lens type is that you don’t have to change glasses when going from indoors to outdoors. The disadvantage is the lens takes minutes to change making things very bright when you first go outdoors into the sun and very dark when you first return indoors. Photochromic lenses may not be the best choice for all safety eyewear applications, but they may eliminate the need to carry more than one pair of glasses for variable work settings. If your organization utilizes photochromic safety lenses for workers, make certain that your safety policy clearly outlines the danger of working indoors with lenses that have not transitioned to clear.

Specialized lens treatments can provide for reduced fogging which can greatly improve performance. Anti-fog coatings can be applied toolycarbonate and other eyeglass lenses, including photochromic lenses. The coating is applied to the lenses before they are machined to the exact sized needed to fit the frames. Some coatings are also effective in reducing glare. Some anti-fog coated lenses require a special lens cloth to wipe the lenses, which also works to improve the anti-fog performance of the coating. The lens coating in conjunction with the lens cloth can result in hours of fog-free performance.

Choosing the right lens for your safety eyewear requires you properly assess the workplace hazards and experiment with different tints, colours, and lens coatings.  Ensure any product you choose is CSA approved and provides the necessary support to ensure the safety eyewear is worn whenever workplace hazards are present. Ongoing advocacy for full compliance with safety eyewear use is important to ensure worker eye safety every day.

Glyn Jones is a partner at EHS Partnerships Ltd. in Calgary. He is a consulting occupational health and safety professional with 35 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.