Why Glass? Why Not? Part 3 of 6

By Bill Heffner


In the lens world, the word ‘occupational’ can sometimes have a negative connotation. They are often seen by a patient as an 'unnecessary' second pair. Since many patients don't understand how lens designs can differ, it can sometimes be a daunting task convincing them that they should have a second pair for a specific task; especially given they usually want one pair of glasses that can do everything. It then comes down to the Eye Care Professional to be able to not only educate the patient, but to also listen to their visual needs. Thanks to free-form technology, we, the lab, can offer a wide range of progressive lens designs that fit a number of different jobs, hobbies, and tasks. It's up to the ECP to find the right design for the patient.

With a brand-new catalog of free-form designs available in glass, it's the perfect time to expand the use of this material in occupational lenses. Since this type of lens tends to be worn for shorter periods of time, it helps to mitigate one of the main complaints about glass lenses – their weight. Since the lenses aren't worn full-time, patients tend not to notice the slightly higher weight of glass as compared to plastic lenses. Occupational lenses are also an ideal place to utilize glass, as there are many jobs and hobbies that benefit from the enhanced optics, scratch resistance, and the chemical resistance of glass.


Hunting, range shooting, and similar activities are one of the higher-demand areas for the best possible visual acuity. Being able to accurately discern a target at range is extremely important. You also want to ensure that the eyes are protected from an unexpected casing being ejected towards you.

Shooters often prefer using a range of tinted lenses, the colors of which can vary depending on what specific kind of shooting as well as the ambient light and weather conditions. One of the more popular colors is a yellow/amber color. This is used to filter out haze and blue light, which makes it ideal for overcast or foggy conditions. Fixed tint glass is rather different to tinting plastic, however. Glass is called fixed tint because the color is added when the lens material is molded, ensuring an even, and consistent color distribution throughout the lens. This is not applied via dying or coating, which is how plastic lenses are often tinted. This means that the tint in a glass lens will stay the same, without fading, throughout the life of the lens.

Shooting is also a complex sport that can also have a variety of different visual demands. Often times shooters have problems with multifocal lenses because they can't find the sweet spot that lets them see their sight as well as the target. They can often have issues with lined bifocals due to the quick jump in power. As such, the difference between pistol and rifle shooting, for instance, requires use of a slightly different progressive lens design, since the distance from the eye to the sight can change dramatically. In order to get the ideal lens for shooting, we will need to tailor the focal distance to the front sight, which is one of the things that is possible with the correct free-form design.


The dirtier the job, the more hazardous it is to the lenses. I'm not talking about safety or impact-resistant lenses, but all of the little things that can ruin a lens. This can range from high levels of dirt, sawdust, or metal shavings to things like grease, acetone, or other chemicals that would damage normal lenses. This is where glass makes a lot of sense, since they are robust enough to stand up against even the harshest condition and still remain in good condition.

Thanks to free-form, it's also possible to now have lens designs that are geared towards dirty jobs. Different occupations will require different visual demands, which mean we need to have a progressive lens design that can meet those demands. In order to address some of these occupations, I'm going to use a number of IOT freeform designs as examples of suggested lens designs, as they are currently the only lens designer available with a full portfolio of designs in glass.

For outdoor occupations such as farming, landscaping, or construction, most of the need for the lens is for intermediate and distance, with minimal need for reading zones. We can use a free-form design such as IOT AlphaH65 or Sport lens to accommodate this type of viewing area. Since these types of jobs deal with a lot of dirt and grime, it's very likely that the wearer is going to try and clean the lenses using an equally dirt-covered shirt. The robust scratch resistance of glass is very important in this kind of a condition, helping to prevent lens damage. It's also good to note the possibility of having  a large number of glass sunwear options utilizing big, wrap-style frames. Ranging from polarized, to fixed-tint, Thin & Dark, photogray/brown, or even polarized photo lenses, glass offers a very wide range of lens options to consumers.

If we look at indoor occupations, we see a shift in the visual demands a patient will need from their lenses. For professions such as mechanics, painters, and shop workers, we see a much greater focus on the intermediate and near visual zones, and very little need for distance. Most indoor occupational progressives these days are focused on computer/desk use, and not really on other indoor occupations. Finding such a progressive lens in glass, however, is not something that's been possible, until now. With free-form, we can now create a progressive design for intermediate/near on the back of a glass lens. If we look at a job like a mechanic, for instance, they are going to be spending most of their 'working time' with their visual zone somewhere between 1.5 and 10 feet. This makes the traditional 'computer lens' design, such as IOT's 'Office Reader' an ideal design for this task. Just because the design was intended for use in an office setting doesn't mean that it can't also be used in other applications with similar visual needs.

The idea of these 'occupational' lenses isn't that the lens designs themselves need to be wildly different from a standard progressive, it's really a question of what specific lens material matches best with each task. This is where it comes down to the Eye Care Professional in order to ensure that the patient has the best experience with their lens. It isn't simply a matter of choosing the one 'best' lens design. We have to ensure that we match a lens design and material to the way a patient will use their lenses. This may mean several different pair of lenses for a patient that engages in numerous tasks with different visual needs. It also means that the lens material needs to be tailored to what the patient does as well, since someone that wears plastic in their everyday lenses may still benefit from glass in their work/occupational lenses. 

This is the third in a six part series exploring the  many uses of glass lenses, dispelling myths around glass and helping to show glass as the premium product it is. The following topics will be discussed:

• July/August: Glass Sunwear Lenses—Premium eyewear, color availability, durability

• September/October: Innovations in Glass Technology—Thinner, lighter, better

• November/December: Specialty Applications for Glass—X-Ray, Contrast Enhancement, Glass Blowing

Bill Heffner, aka Other Bill, is the director of IT, marketing and sales for FEA Industries. Other Bill is a fourth-generation lab executive following in the footsteps of his father, grandfather, and great-grandfather. Other Bill has worked at FEA in an on and off capacity for most of his life coming aboard full time in September 2009. To reach Bill with comments on this article email him at [email protected]






Labtalk June 2020