Lifestyle + Fashion

Fast dark. Fast clear: modern self-tinting lenses

Are you looking for a new pair of glasses with self-tinting lenses that will give you 100% protection from the sun and harmful UV rays and mean you can forget all about your conventional glasses

24 November 2022

Say goodbye to switching glasses: Are you looking for a new pair of glasses with self-tinting lenses that provide full protection of harmful UV radiation? Did you know that lenses that darken in the sun are now popular modern miracles that offer optimum vision? We’ll tell you why you should buy them and what you need to look out for.

  • Fast dark. Fast clear: modern self-tinting lenses

Also known as self-tinting lenses,  photochromic lenses have been around since the 1960s. This small yet significant discovery made by chemist Stanley Donald Stookey and his colleague William Armistead was what made it all possible. They produced lenses that react to UV radiation and have the ability to tint.

Since then, a lot of improvements have been made in terms of the quality and performance of self-tinting lenses. Many people who simply cannot function without their glasses and often switch between indoors and outdoors just love them. Here are some things you should know about these little allrounders:

What are the differences in quality amongst self-tinting lenses?

With self-tinting lenses, there’s no longer a need to change glasses. ZEISS wanted to know exactly what was important to people wearing photochromic glasses. Wearers have very clear demands in terms of quality and performance:

  • In order to be convenient, self-tinting lenses must adjust very quickly to the changes in light conditions.
  • To attain optimal vision, self-tinting lenses must turn very dark in the sun and completely clear indoors.
  • Self-tinting lenses offer full UV protection.
  • To look good, self-tinting lenses should be available in attractive, harmonious tints.
  • Self-tinting lenses should have a long service life and offer high performance.
  • They should be compatible with all frame types and all kinds of glasses.

These are all qualities that ZEISS PhotoFusion X Lenses have. In just 15 to 30 seconds, PhotoFusion®  X Lenses will darken in the sun. Indoors, they will clear up again in about 5 to 10 minutes1. They offer full protection against harmful UV radiation. So it doesn’t matter if the sun is shining or if there are great big clouds in the sky: during the day, our eyes are exposed to UV radiation. For many, it’s become routine to use skin creams with UV protection. But creams don’t protect your eyes or eyelids without an unpleasant burning sensation. Protecting your eyes – glasses with UV protection do it as a matter of course.

How do photochromic, or self-tinting, lenses work?

How do photochromic, or self-tinting, lenses work?

A chemical reaction involving certain molecules is used as the basis for photochromic lenses. The secret behind ZEISS PhotoFusion X Lenses are photo-active molecules which react quickly to changing light. When incident light changes,  particulary the intense of UV, molecules undergo a change process that causes lenses to darken or clear up. Thanks to an innovative way of combining these molecules with ZEISS lenses, it has been possible to design the next generation of powerful self-tinting lenses.

For self-tinting lenses, the term “photochromic” (from the Greek words phos = light and chroma = colour) is also often used. This term is used to describe the same type of lenses.

Try it out for yourself – speak to your optician today. ZEISS PhotoFusion X Lenses are available as  single vision lenses,  progressive lenses  and with all ZEISS coatings such as  DuraVision Premium.  They’re also available as  Digital lenses.

10 questions and answers on self-tinting lenses with PhotoFusion X

10 questions and answers on self-tinting lenses with PhotoFusion X
  • A huge amount of UV radiation is absorbed by the windshild which has an effect on the lens performance. Fortunatley,  the PhotoFusion X Lenses retain more of their self-tinting performance in the car than previous generations.  For long trips, sunglasses are still recommended.

  • Yes, PhotoFusion X Lenses appear almost totally clear to the wearer when they’re back indoors.

  • For general use PhotoFusion X lenses offer excellent overall visual performance and glare protection. Nevertheless, under intense sunlight in environments with high temperatures, inside cars with windshields that absorb most of the UV radiation, or in environments with intense reflective glare from surfaces such as water and snow, a pair of prescription sunglasses with a fixed tint will offer the best form of glare protection and visual comfort.

  • Self-tinting PhotoFusion X Lenses with high and medium refractive indices react at a very high speed: they darken up to 60 percent faster1 than the previous generation  of ZEISS  PhotoFusion – and clear up again up to 2.5 x times faster2 than a  well-known  photochromic brands latest generation.


  • Depending on the intensity of UV in the shade, self-tinting lenses will not be as dark as they are in direct sunlight and therefore only become slightly tinted. However, they still offer full UV protection.

  • Yes, they are as suitable for driving at night as any other clear lens.  

  • ZEISS PhotoFusion X Lenses protect wearers’ eyes against UV at all times.

  • Yes, ZEISS PhotoFusion X Lenses are virtually clear in their faded state, making them perfectly suitable for use indoors and at night. Furthermore, when exposed to sunlight, ZEISS PhotoFusion X Lenses darken as needed to maintain sufficient glare control in bright sunlight. You can choose ZEISS lenses with PhotoFusion X to meet your particular needs.

  • Unlike clear lenses, self-tinting PhotoFusion X Lenses darken when the surrounding light intensifies. Indoors, they are almost clear and, when exposed to bright sunlight, darken to a degree that is comparable to standard sunglasses. This means that they protect against glare and offer enhanced visual comfort.

  • PhotoFusion X Lenses from ZEISS are produced with the latest self-tinting technology and therefore offer a high level of performance. They darken up to 60 percent faster1 and clear up again up to 2.5 x times faster2 than a  well-known  photochromic brands latest generation. In addition, PhotoFusion X Lenses provide high performance over the long term.

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  • 1

    Analyses by Technology and Innovation, Carl Zeiss Vision GmbH, DE 2021 in accordance to ISO 8980-3. Based on the average speed (%T/min) of activation from clear state to 30%T at 23°C in grey 1.60 index and polycarbonate in HC only form.

  • 2

    Testing by independent laboratory in USA, 2021 according to requirement in ISO 8980-3. Based on the average speed (%T/min) of fade-back from fully activated state to 80%T at 23°C in grey 1.50 index (CR607) HC only form.