Safety eyewear

RIGHT BEFORE YOUR EYES

By Hayley Chandler

There’s more to safety glasses than meets the eye. Here’s a look at the features to watch for -- and the pitfalls to keep an eye out for

If you’ve watched the changes in safety eyewear in recent years, you’ve noticed that people wearing safety glasses are looking good. Manufacturers have caught on to the idea that workers want fashionable, attractive safety glasses, and it is now much easier for people to find protective spectacles in a style they are willing to wear. However, when it comes to purchasing safety glasses there are many other considerations that are not quite as obvious.

Although today’s safety frames look like standard fashion or dress frames, they are not the same. Industrial safety frames are designed to hold the lenses in a way that reduces the chance of them being pushed backward out of the frame upon impact.

"You can get acceptable industrial frames in both plastic and metal," says Ralph Chou, associate professor for the school of optometry at the University of Waterloo, and a mamber of the Canadian Standards Association (CSA) Technical Committee on Eye Protection. However, metal can be problematic in certain work environments. Some industries discourage use of these frames because of concerns that they conduct heat and electricity. And, in hot workplaces, the plating on metal frames can be corroded by perspiration, sayd Don McDonough, Safety Rx Manager for Levitt-Safety in Oakvill, Ont.

Side protection is another major issue, and many wearers of "safety glasses" will be surprised to learn that their eye protection does not meet the CSA standard. "If you don’t have a side shield, you just don’t have enough protection," says Chou. In fact, the CSA’s standard for Industrial Eye and Face Protectors (CAN/CSA-Z94.3-92) states that "protective spectacles shall have permanently attached or removable side shields."

Side shields come in full, cup-type, semi- or flat-fold designs, which may or may not be ventilated. Side protection is also provided by safety glasses of various types with wrap-around lenses that curve around the side of the head. In order to be certified by the CSA, all these styles must cover the whole temple area.

The style you choose will depend on what is needed to provide maximum protection and comfort. A wrap-around cup with brow guard gives the greatest protection against flying particles. Perforated plastic cup side shields provide more ventilation. Wire mesh side shields are cooler than plastic ones and are often used in hot environments for protection against larger particles. If the lenses of your safety glasses feature filters that provide protection from ultraviolet, visible and infrared radiation, the side shields must provide the same or greater protection.

Lens material

Lenses for safety glasses are usually available in plastic (CR39), polycarbonate or glass. Each has advantages and disadvantages that must be considered in terms of the specific work environment and needs of the worker.

There are no CSA certified or approved products on the market incorporating glass lenses because they do not meet the association’s impact protection standard. This is despite the fact that glass lenses used in safety eyewear are thermally tempered (heat-treated) to improve their impact resistance. However, glass lenses are sometimes chosen for safety glasses because they are more scratch-resistant than other lens materials. If glass lenses are chosen, an additional form of eye protection such as CSA approved goggles should be worn over them when exposure to impact hazards is anticipated, says Chou.

Plastic lenses offer greater impact resistance and they are lighter than glass, making them more comfortable to wear. Unfortunately, plastic offers low abrasion and scratch resistance and poor resistance to impact by sharp or pointed objects. Both glass and plastic lenses are significantly weakened by scratches or chipped edges.

Polycarbonate lenses provide the highest level of impact protection -- this does not mean they are unbreakable -- and retain this resistance even when badly scratched. They are an excellent choice for workers who are at high risk of exposure to flying particles. These lenses are also lightweight. "Inherently, the polycarbonate, as it is made up in clear lenses, has very good ultraviolet protection," says Chou. "For example, it would provide against environmental sunlight exposure." A serious disadvantage is that polycarbonate lenses scratch easily even when treated with a scratch-resistant coating.

If you want a tinted lens, chances are you won’t get a very get a very satisfactory result from a polycarbonate material, says Don McDonough. This is because the scratch-resistant coating applied to polycarbonate lenses is very hard and "that takes away from its ability to tint," he says. Plastic lenses, on the other hand, take tint very well.

Some other disadvantages are evident when polycarbonate is used for prescription safety lenses. It "has a greater dispersion rate than CR39, which means that on the edges and moving toward the center of the lens there’s more distortion than there is in plastic," says Ed McRae, director of vision care plans with the Alberta Association of Optometrists in Edmonton, Alberta. "So when you start to go into a higher prescription, polycarbonate creates a lot more distortion and that can sometimes really bother people."

Problems can also arise when special coatings are applied to polycarbonate lenses. "We know that, for example, there are certain types of scratch-resistant or anti-reflective coatings that can be applied to polycarbonate that, for the purpose of scratch resistance or reducing reflection, work very well," says Chou. "The trouble is that they alter the material characteristic so that the impact resistance is lost."

"So one has to be extremely careful, particularly in the prescription market, to ensure that, where there is a specific need for high energy impact protection, lenses are not being given any of these other treatments which could potentially weaken the lens," Chou says.

Prescription lenses are of particular concern because they are not currently tested or certified by the Canadian Standards Association. "The [CSA-Z94.3-92] standard dictates that you test the complete pair of safety glasses -- or whatever the eye guard is -- assembled and ready to be provided to the user," explains Chou. Plano (non-prescription) safety glasses are certified as units. "But you can’t use the same kind of approval system for prescription eyewear because of the custom nature," Chou says. It is not feasible to perform an impact test on each pair made.

However, the CSA does require that safety glasses with prescription lenses satisfy all the requirements of CSA-Z94.3-92 except for those that relate to lens impact requirements. This means prescription lenses must be placed in CSA-approved frames with either permanently attached or clip-on side shields. The CSA recommends that prescription lenses be at least three-millimetres thick and made of plastic or polycarbonate.

"There’s a lot of confusion in the ophthalmic industry as to what to do with people who need prescription safety eyewear," says Chou. "The CSA standard is under review and will more than likely be revised within the next year or so," he says. The CSA Technical Committee on Eye Protection is now dealing with the issue of what constitutes adequate protection in prescription safety eyewear. But, "I don’t know where that’s going to go yet," Chou says.

Ensuring a proper fit

Workers who purchase prescription glasses should have their eyewear professionally fitted. Temple length (the arms of the glasses), eye size, distance between pupils, and bridge size should be measured to ensure that the wearer is looking directly through the optical centre of the lens and can see properly. A good fit also ensures glasses fit comfortably and snugly. "You don’t want large air gaps between the edge of the frame and side shields, and the skin of the face," says Chou. Spectacles should not slip when the wearer lowers his or her head.

Proper sizing is also important for those who wear plano safety glasses. Although one-size-fits-all styles are available, it is preferable to provide a wide range of sizes. "You can’t expect that everybody’s going to fit the same pair of glasses," says Chou. "Faces are different sizes and shapes and configurations and you have to allow for that in selecting eyewear for a group of workers." In fact, the CSA recommends that spectacle-type protectors "should be available in an adequate range of eye, bridge, and temple sizes and the wearer should be assisted by a qualified person to ensure a proper and comfortable fit." It is also necessary to readjust glasses periodically to maintain a good fit.

Care and maintenance

It is difficult to see through lenses that are pitted or scratched, and such marks significantly lower the impact resistance of glass and plastic lenses. Damage to frames, such as cracks or loose parts, also affect safety performance. For these reasons, spectacles should be inspected regularly, and damage should be immediately repaired or broken parts replaced. The CSA advises that "damaged or worn parts should be replaced by identical parts as produced by the original manufacturer to assure total integrity."

One way to protect spectacles is to store them in their cases. It is also important to properly clean them. "Always clean your eyewear wet, " says McDonough, in order to avoid scratching the lenses. He recommends the following cleaning procedure. "Rinse them first to remove any heavy particles. Clean them with soap and water. Dry them with a soft cloth. Make sure that there’s not moisture left in the temples or in the nose pad because that will all turn colours. You have to be a little bit meticulous about cleaning all the body oils out from the crevices. Use hot water if you have access to it. The hotter the water the better." Spray-on lens cleaners, often available from wall-mounted dispensers in the workplace, also work well when used with the lens-cleaning tissues provided.

In a quarterly newsletter promoting occupational vision care, the Alberta Association of Optometrists warns that polishing lenses with products such as toilet paper and paper towels "can cause a build up of tiny hairline scratches that eventually cause a foggy film, usually right in the middle of the lens." Lens tissues were declared the best choice for the job. And cloth lens cleaners -- providing they are clean and kept stored in their case -- received a good rating. These products are specially designed to be non-abrasive and lint-free.

As with all personal protective equipment, safety glasses are effective only if they are worn. Which brings us back to appearance. People are more likely to wear styles they like. If you take that into consideration while making sure that eyewear meets the standards, fits properly and is in good condition, workers will not only be looking good, they’ll be seeing well for a long time to come.

Hayley Chandler is associate editor of safety purchasing for OHS CANADA.

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How To Recognize Approved Safety Glasses

* Plano (non-prescription) safety glasses should be certified by the CSA. If they are, the association’s logo will be permanently placed on at least one component. Typically, it appears on the inside of one of the temples.

* A permanent mark identifying the manufacturer or supplier should be visible on both lenses, the front of the frames, both temples, and on the side shields if they are removable. This is helpful if you need to replace damage or worn parts.

* Prescription lenses are not certified by the CSA but the manufacturer's monogram should still be marked on each lens. In addition, glass lenses must carry a permanent "G" marking.

* Frames for prescription safety glasses must be the same as those for non-prescription lenses but they will not carry the CSA logo.

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Buying Tips

Keep the following points in mind when selecting safety glasses:

* Workers should have their eyes examined even if they do not currently wear corrective lenses. People’s visual acuity changes and they do not always recognize the need for prescription eyewear. A professional eye examination can also detect problems such as glaucoma and cataracts.

* When shopping for safety glasses, request "industrial protection" lenses and frames.

* Note that impact-resistant lenses and safety lenses are not the same. Impact resistant lenses are used in regular glasses and do not meet the stringent requirements of safety lenses.

* Ensure that non-prescription safety glasses are CSA certified. Glasses certified by the American National Standards Institute (ANSI) do not meet the same requirements. The CSA uses a method of testing impact resistance that is more predictive of lens performance in real life.

* Solicit workers’ opinions and purchase the style of spectacles they prefer. This helps ensure that workers will actually use the protection your company provides.

* Pay particular attention to the quality of the parts of the glasses that come in contact with the face, says Don Mcdonough. The nosepiece should not be flimsy. Examine the temples where they connect to the frame.

* Look for eyewear with adjustable temple arms, that allow wearers to adjust the fit.

* "Metal frames are easier to adjust than plastic, because in most cases they have adjustable nose pads and those kinds of things," says Ed McRae. They are also more flexible.

* Look for features, such as padding to protect the sensitive areas behind the ears, that will make glasses more comfortable.

* Cable temples, which curl around the ear, allow a snug fit. Spatula temples are designed to rest on top of the ear and are more prone to slip off if the user frequently bends over.

* Do not use photochromic lenses (which darken when exposed to sunlight) in the workplace because vision is impaired for a short time while the glasses reverse from dark to light.

Glasses with anti-reflective coatings get dirty very easily, warns McDonough. However, "it’s a trade off," he says. "You get better vision because they do have better clarity."

* Workers purchasing prescription eyewear should tell the person who is prescribing or dispensing the glasses that they need safety eyewear and then discuss the type of work they do, says Ralph Chou. The provider needs this information in order to give the proper advice and help make the appropriate selections of lenses and frames.

* Always have safety glasses fitted by a trained person.

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