Choices, Choices

Breaking down the components of protective eyewear can help employers ensure workers' quality of life.

• By Larry Garner
• Oct 01, 2005

IT was a normal work day for J.D. Buske. With the blink of an eye, all of that changed. He almost became one of the one thousand daily eye injury statistics reported in the United States. Here's his story: "Hello, my name is J.D., and I live in San Antonio, Texas. Today your product saved my right eye and prevented me from serious injury to my face. Let me explain what happened. I was operating an 8550 Vermeer rock saw when the cutting wheel kicked up a 10 inch long, 5 inch wide rock that hit me in the face, causing me to lose some of my skin on the right side of my nose (about 60%) and a concussion. The glasses prevented the rock from entering my eye. I'm going to have to replace the glasses, of course, but I just wanted to thank your company for making a great and safe product."

As safety providers, we have an opportunity to recognize that, according to OSHA, 90 percent of eye injuries could be prevented with protective eyewear. Preventative measures ensuring proper protective eyewear would reduce the $1.25 billion in workplace costs, including worker's compensation, medical payments, productions slowdowns, etc., according to OSHA.

Fueled by fashion, protective eyewear styles are evolving daily. Safety distributors and suppliers are challenged to turn inventories and keep pace with fashion trends. In addition to protective eyewear, goggles, faceshields, and emergency equipment such as eyewash stations contribute to providing employee safety and being compliant with OSHA's rules. Protective eyewear consists of lenses, frames, temples, hinges, and nose pieces. Better understanding the features and benefits of these components better prepares you to help reduce eye injuries and protect quality of life. Here is a recap of our industry's most popular styles, broken down by components:

Lenses
Lens tints play an important role in giving wearers the appropriate eye protection for their given application. There are many lenses to choose from. Below are the most commonly used lenses.

1) Clear. This is the most commonly used lens and is to be used mainly indoors in normal light environments. When made with 100 percent polycarbonate material, even clear lenses offer 99.9 percent UV (ultraviolet) protection.
2) Gray/Smoke. Used in environments with excessive light, usually outdoors. Road construction crews, home construction workers, and roofers are prime candidates for these darker lenses. They, too, offer UV protection and, at the same time, block up to 88 percent of visible light.
3) Mirrored. Like Smoke lenses, mirrored lenses offer extra protection for use outdoors. Additionally, these lenses offer extra "flare" for the style-conscious worker.
4) Indoor/Outdoor--Clear Mirror. Good in environments with medium light. Whether they are working indoors under bright fluorescent lights or outdoors on an overcast day, workers get the reduction of glare they want with this lens, yet it still allows workers ample light transmission to not hamper their vision while viewing objects in low light. These lenses block 45 percent to 55 percent of visible light. (Compliance for indoor use is subject to state OSHA regulations. Please check with your OSHA inspector for compliance questions.)
5) Amber. Offers added contrast and improved vision in low-light areas. The use of this lens helps workers see potential dangers in low-light work environments, such as road construction at night.
6) Vermillion/Rose. Enhances contrast while reducing all colors equally for optimal color recognition. Ideal for indoor inspection.
7) Light Blue. Serves the same purpose as grey lens, yet allows more visible light through the lens for indoor/outdoor use. Reduces glare from artificial light, such as halogen and fluorescent.

Two additional considerations for all lenses are anti-fog and anti-scratch coatings. While most lenses feature anti-scratch coating, some lenses are available without this coating for a more economical option. Environments with high humidity or sudden temperature shifts create additional risks because of lens fogging. Be sure to recommend anti-fog lenses for these environments.

There are many other colors and tints available in protective eyewear. Please discuss the uses and applications with your protective eyewear supplier.

Lens tints are not the only choice to make when choosing the appropriate protective eyewear style for your workers. The shape and construction of the lens play an important role in giving your workers the proper "Optical Fit." "Common" lens construction includes single lens designs, dual lens designs, and single lens designs with dual lens functions.

1) Single Lens Design. When manufacturing a lens, designers can integrate only one "Optical Center" into the lens. The optical center is the optimal place to view through the lens. In a single lens design, there is only one optical center. It is normally in the center of the lens above the nosepiece. In this position, it is an equal distance away from each eye. For more than 70 percent of the workforce, this is acceptable because their interpupillary distance falls into the normal category. However, the remaining 25-30 percent, with interpupillary distance outside the norm, will experience headaches, eye strain, or eye fatigue.
2) Dual Lens Design. In this design two lenses are present; lens left and lens right. Each lens has its own optical center. These optical centers are closer to the pupils of the wearer and, in many cases, will eliminate headaches and eye fatigue.
3) Single Lens Design with Dual Lens Function. This is a one-piece lens that has two optical centers. These lenses usually have a crease above the nosepiece that resembles two lenses being fused together. This lens gives the style wanted from single lens designs while solving problems of employee headaches.

Most protective lenses are either geometric based, such as spheres, cylinder, cones, or torix, or are non-geometrical aspheric lens (not spherical).

1) Spherical. These lenses are geometrically based on a sphere. The amount of curvature from top to bottom is exactly the same as the amount of curvature from side to side. This curvature is measured using "Base Curve." Typically, Base Curve is valued using a "Base Curve Number" (e.g., 6 Base Curve, 8 Base Curve). The amount of Base Curve has less to do with optics and more to do with radius of the sphere. Manufacturers tout Base Curve to prove their eyewear has ample coverage around the eye orbit. A key to remember is, "The higher the Base Curve Number, the more curvature in the lens."
2) Aspheric. These lenses are not geometrically based on a sphere, so the curvature changes throughout the lens. This type of lens allows for a relatively flat viewing area in front of the eyes, yet has enough curvature to give ample coverage at the sides. "Base Curve" does not apply to this type of lens. This design extends 180 degrees of unimpeded vision while offering superior eye orbital seal.

One company has gained the technology to use a single lens, aspheric design and incorporate a lens that has multiple optical centers. Instead of having just one optical center in the lens, the entire viewing area is one large optical center. With this lens, employers can "Optically Fit" all employees with one style, with no worry of their interpupillary distance's being out of the norm.

Frames
Traditional frames primarily consist of nylon, metal, polycarbonate, and other plastic materials. Today's offerings include an assortment of features incorporated into these same materials. Specific examples include:

A) Metal. Provides excellent durability, as well as some adjustability.
B) Nylon. Lightweight, dielectric, and stylish designs:
1) Multi-material technology: Combination of different materials with additional brow padding.
2) Ventilation channels: Contributing to fashion and cosmetic appeal.
3) Adjustable brow bar: Designed to accommodate a wide assortment of individuals.
C) Polycarbonate. Economical alternative without sacrificing durability.

Temples
Spatula and bayonet are the most common temple designs. All individual styles could offer some form of padding for grip and comfort.

A) Spatula. The most traditional style, which wraps downward behind the ear.
1) Ratchet: Varying degrees of adjustability to position the frame closer to the face as needed, depending on angle of vision.
2) Extension: These temples have varying degrees of adjustability to provide longer or shorter temples as needed.
B) Bayonet. As its name implies, this is a straight design resting on top of the ear. Various temple sleeve materials are often added to enhance non-slip and provide additional comfort.
C) Hybrid. A combination of spatula and bayonet design.
D) Wire core. Plastic outer covering with wire inside for adjustability.

Hinges
A) Spring hinge. A resilient action to aid in donning and doffing, as well as comfortable fit.
B) Traditional hinge. Functions solely to provide temple movement; generally attached with metal screw.
C) Hinge-less frame. Nylon, single piece construction designed to better dissipate impact or metal design for lighter weight and greater comfort.
D) Interlocking (snap together). Engineered to attach temples to frame without using metal parts.

Nose Pieces
A) Molded. Universal fit nose bridge design fits the highest percentage of the workforce. This style is typically molded into the polycarbonate lens design.
B) Gel nose piece. Made of soft material to conform to shape of the nose. This style is recognized for offering the most grip, and some styles are replaceable.
C) Fingers. Ribbed construction designed to conform to shape of the nose.
D) Adjustable. Twin bridge with adjustable pads.

This article appeared in the October 2005 issue of Occupational Health & Safety.

This article originally appeared in the October 2005 issue of Occupational Health & Safety.