Testing That Little Bit Extra

As early as 1959, ZEISS launched its first anti-reflective coating for mineral eyeglass lenses and has since then continuously expanded coating functionalities and performance. Currently, in addition to ZEISS DuraVision Gold UV, there are other premium coatings available for clear lenses and prescription sunglass lenses (for example, ZEISS DuraVision Platinum UV and ZEISS DuraVision Chrome UV)¹, as well as functional coatings and special premium coatings for sunglasses².

The science behind coatings is unique and highly technological. The ion-assisted vacuum deposition process of up to nine ultra-thin metal and ceramic oxide layers with a thickness of just 2 µm in a vacuum chamber is equally impressive³. But how exactly and how rigorously are these coating properties tested, and who sets the standards? Two examples provide insights into quality assurance and performance evaluation of premium coatings.

Thanks to the new integrated ZEISS CleanGuard technology in ZEISS DuraVision Gold UV, an initial contact angle for water of 117° is achieved, significantly more than in previous coating generations. Even after a wear time of 14 months, and thus cleaning for over a year, the contact angle was still at 105°. This indicates that even after more than one year of wear, coating still retains a high level of water-repellent and easy to clean properties.
Additionally, the contact angle for the oil-like chemical substance hexadecane was tested. This serves as a control test example for non-polar liquids such as skin residues or greasy fingerprints, which, as eyeglass wearer knows from experience, tend to stick very well. Even for this everyday contaminant, an excellent initial contact angle of 73° was achieved. This positive result is confirmed by consumers in surveys: nine out of ten say that fingerprints on ZEISS DuraVision Gold UV eyeglass lenses can be easily removed.⁵

That anti-reflective coatings can also have an aesthetic value is due to their subtle residual reflection color. While, pioneered by ZEISS with DuraVision Platinum UV, a cool blue reflection color has become an industry standard, now, ZEISS DuraVision Gold UV introduces a new golden residual reflex color option that has a unique and subtle touch of luxury and sophistication. How well this is perceived is a matter of taste. However, it is certain that gold is timeless and stands for elegance and high quality. Specifically for ZEISS DuraVision Gold UV, it can be stated: In a representative survey, 66 percent of respondents said they liked the look of the eyeglass lenses with the unique golden residual reflex well or very well. Seven out of ten also agreed with the statement that these eyeglass lenses match well with brown or golden frames.⁶

While the quality and performance of a coating can be determined through standardized tests, the subjective perception of eyeglass wearers is always important. This influences how much a wearer likes their new eyeglass lenses with all the additional features for which they are paying more. To get a complete picture, ZEISS therefore also relies on wearer trials and consumer surveys. As was done for ZEISS DuraVision UV Gold: 90 percent of respondents say that the surface of the eyeglass lens with ZEISS DuraVision UV Gold feels smoother. The same percentage of respondents agrees that these lenses are easier and faster to clean. And 93% agree that eyeglass lenses with ZEISS DuraVision have a greater water repellence.⁷

For eye care professionals, it is particularly important: consumers often measure the quality of their eyeglass lenses by the coating. In addition to lens design and prescription, the coating itself plays an important role in providing vision clarity for the wearer. Coatings influence how clean eyeglasses stay throughout the day, how easy they are to clean, how well they reduce glare and reflections, and how scratch-resistant they are. In a large-scale consumer study⁸, 88 percent of respondents said that clear and sharp vision is very important to them regarding their eyeglass lenses. "Scratch-resistant" was rated as very important by 82 percent, and "easy to clean" by 80 percent. Both are factors that contribute in the long run to being able to see clearly and sharply through one’s eyeglass lens. For eye care professionals, these are important additional selling and differentiation arguments.