By Bill Heffner

Glass lenses still maintain a high degree of popularity in the premium sunwear market. Often, customers will spend money on brand name frames, but most times the lenses are an afterthought. When we examine the high-end sunwear market, glass has its definite niche. If you ask older patients about their favorite pair of sunglasses, most say it had glass lenses. They enjoyed the optical performance and the durability of glass. The lenses shouldn’t be an afterthought to the frame, they should be another selling point. Glass helps add a feeling of worth to any frame, especially given the quality, availability, and value that glass brings to the patient experience.


Two absolutes about sunwear is that sunglasses are going to be worn outside and the lenses are going to get dirty. When we look at outdoor activities like hiking, the beach, or even yard work around the house, there's a lot of potential for lenses to get scratched. Dirt, sand, sweat, and other nasty things are going to get all over those lenses. Since they are outside, that also means most of the cleaning surfaces—shirts, sleeves, tissues—are going to be dirty as well. For most plastic and polycarbonate lenses, they will most likely get scratched. With glass, you can rest assured that you’re going to get the best possible scratch resistance. This is a major selling point for most sunglass wearers, especially ones that aren't particularly kind to their lenses.

Improved optics is another benefit of glass. Some customers want the best they can get, and with glass, that's the best vision they are going to get. When we look into other uses of glass where quality counts, we get a very consistent message. Camera lenses, telescopes, even phoropters. (I haven't seen a photopter manufacturer that has opted to use polycarbonate lenses over glass!) These are just a few examples that show how glass can be the better choice.


For glass sunwear, you have a number of options when it comes to the colors available. This includes polarized, fixed tint lenses, as well as photochromic polarized options. Glass and tinted lenses present some different properties when we compare this to tinted plastic lenses. When we look at plastic, it's basically the same as dying an Easter egg – you pick the color dye you want, dip the lens, and you're done. It's easy enough to get the color you want so long as you can get the dye the correct. With glass, we can't do this. Glass is hard. Really hard. While this is a good thing in terms of chemical resistance, it means that it won't absorb dye. This is why glass tints are often referred to as 'fixed tint' lenses. They are fixed because that's the way they come. When a batch of glass lenses are made (usually referred to as a 'melt'), the dye is added as part of the process. This means the color is locked into the lens, with the dye distributed throughout the material. This gives glass tints distinct advantages and disadvantages when compared to plastic tinted lenses. The fixed tints of glass are much more restricted in terms of colors – if it's not made as a fixed tint, there's no way to make it. However, the common colors are readily available (gray, brown, green, rose, yellow) so it covers the majority of needs. The one benefit that a fixed tint glass lens has, however, is longevity and consistency. Since the color is locked in the lens, every lens is going to be the same exact color. It also means that the color isn't going to fade with the life of the prescription, so it's going to look as good in several years as it does now.

This is the fourth 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:

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