ZEISS BlueGuard: What's behind the new technology?

ZEISS introduced this simple metric because there is currently no industry standard to quantify blue light blocking in spectacle lenses. Alternative formulas used by competitors include various factors in their calculations, such as solar spectral weighting. We decided to use a simple calculation basis. The aim is to provide a general and valid description that everyone can easily understand. For this reason, we deliberately reduced the underlying calculations for ZEISS BlueGuard to a purely physical, objective consideration: transmission. The Blue Violet Block (BVB) measures the percentage of potentially harmful blue-violet light that is blocked by a lens between 400 and 455 nm.

The latest ISO blue light report notes that blue light up to 455 nm offers the greatest phototoxic risk for retinal pigment epithelium.¹ The report suggests minimizing blue light up to 455 nm and maximizing longer wavelengths to avoid interfering with the circadian rhythm and other functions. Accordingly, ZEISS BlueGuard Lenses are designed to partially block blue light between 400 nm and 455 nm while allowing longer wavelengths to pass. In addition, ZEISS BlueGuard Lenses offer complete protection against ultraviolet radiation up to 400 nm. Since 2018, this protection has been the standard in all clear ZEISS lenses and is therefore not explicitly included in the calculation of the Blue Violet Block mentioned earlier. In fact, this also explains the lower limit of the BVB calculation.

Blocking more blue light, as well as other wavelength bands, is possible, and we are familiar with it from looking into special gaming glasses or products from competitors. However, we decided to absorb much blue light, especially in the low wavelength range, without affecting the positive properties of blue light in the higher wavelength range.
This is also a discussion of materials science. The underlying question that needs to be answered is: What is the possible material configuration that will give me the best possible protection while maintaining high light transmission? If more blue light is blocked, for example, the light transmission and thus the aesthetics of the lens will change. This can result in orange or yellow discolorations. With ZEISS BlueGuard, we chose a configuration based on materials science that combines the best possible protection with high clarity and aesthetic acceptance at the same time.

A common disadvantage of many blue light blocking solutions is that they produce irritating and disturbing reflections in the lens surface. As we spend more and more time in virtual meetings or calls where we are illuminated by digital blue light, the aesthetics of blue light blocking lenses have become increasingly important. More than ever before, people see themselves and others on screen for extended periods of time. Lenses that look good without irritating blue reflections are now top of mind. To be honest, in online meetings, we all want to impress people not only with our expertise but also with our overall appearance. As blue light blocking properties now are incorporated into the lens material, ZEISS BlueGuard Lenses come standard with ZEISS DuraVision Platinum UV. This premium anti-reflection coating with its subtle blue residual reflection ensures that the wearer does not get annoyed by irritating reflections, and the eyes are clearly visible behind the lenses. With ZEISS BlueGuard, our aim is to offer a combination of protection focused on the spectral range that matters and best clarity by up to 97.8% luminous transmittance.² In other words, look good and be well protected.

Thank you very much for talking to us!

_{1 ISO/TR 20772:2018-10, Ophthalmic optics - Spectacle lenses - Short wavelength visible solar radiation and the eye.
2 Inhouse measurements and calculations based on the BVB (Blue-Violet-Blocking) metric. Analyses by Technology and Innovation, Carl Zeiss Vision International GmbH, DE, 2020.}