Did you know …

… that millions of molecules are hard at work on ZEISS PhotoFusion lenses?

Part 15: Did you know …

… that millions of molecules are hard at work on ZEISS PhotoFusion lenses?

To produce a ZEISS self-tinting lens, millions of light-sensitive molecules are incorporated into a coating that goes onto the lens at a thickness of only 0.05 millimetres. These molecules actually alter their chemical structure when exposed to UV rays. Like flower buds, the molecules unfold and darken the lenses in the presence of UV rays. When the level of UV rays drops, the molecules fold again and the lens becomes clearer. These miracle molecules provide greater visual comfort in changing light conditions!  

One pair of glasses for all your vision needs – that's what many spectacle wearers are looking for! Lenses which automatically adjust to all light conditions eliminate the need to switch glasses, significantly boosting the wearer's comfort and safety. Modern self-tinting lenses have come a long way in this respect, offering significantly faster reaction times and major improvements in performance.

What makes ZEISS PhotoFusion self-tinting lenses such a good choice?

When ZEISS asked glasses wearers what they want from self-tinting lenses, five key criteria came to the fore:

  • Fast reaction time: to be comfortable to use, self-tinting lenses must adjust as quickly as possible to changing light conditions.
  • Dark outdoors, completely clear indoors: to provide optimum vision, self-tinting lenses must darken in sunlight and be completely clear indoors.
  • UV protection: self-tinting lenses must offer outstanding performance and 100% UV protection.
  • Appearance: to look good, self-tinting lenses should be available in attractive tints.
  • Durability: self-tinting lenses should have a long service life and offer outstanding performance.

ZEISS self-tinting lenses with PhotoFusion meet all these requirements. It takes just 15 to 30 seconds for PhotoFusion high and mid-index lenses to darken to the equivalent of sunglasses in bright light or in the sun. Indoors, they turn completely clear again within 5 to 10 minutes. Of course, PhotoFusion also offers 100% protection against solar UV rays, even when the lenses are clear. PhotoFusion is available in a natural, brown or grey tint, providing ideal conditions for good vision and an attractive appearance. The technology is highly durable, guaranteeing excellent performance over many years.

*Average value for 1.67 and 1.6 and for lenses made of polycarbonate. The performance is dependent on the material. temperature and light conditions.

Light-sensitive molecules work hard to get the job done!

As part of the self-tinting lens manufacturing process, special light-sensitive molecules are applied to the surface of the lens. These react to high-energy UV light.

This technique utilizes a chemical reaction which was first developed in the 1960s by chemist Stanley Donald Stookey and his colleague, William Armistead, as a way of tinting lenses automatically. The surface of these photosensitive molecules 'unfolds' when sunlight hits the spectacles, causing the lens to darken. The stronger the sunlight or UV light, the darker the lens becomes. When the level of UV rays drops, the molecules 'fold' again and the lens becomes clear again. In PhotoFusion lenses, these molecules have been optimised to ensure they do their job as fast as possible.

That's how self-tinting lenses with ZEISS PhotoFusion work.

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What situations are self-tinting lenses recommended for? And who benefits from them most?

  • 1. Convenience: Self-tinting lenses by ZEISS for everyday use

    Do you need your spectacles all the time? Does it bother you always having to carry two pairs of spectacles at all times so that you can see perfectly indoors and protect your eyes against glare and UV rays outdoors when it is sunny? Spectacles with self-tinting lenses can make your life more comfortable, as you always have the right tint for all light conditions in one set of spectacles. PhotoFusion prescription spectacle lenses with a high or medium refractive index darken in just 15 to 30 seconds in bright light or sunlight*. Indoors, they brighten again in 5 to 10 minutes*, becoming clear enough to see distinctly in a short time. Of course, they also offer 100 per cent protection against solar UV rays at all tint levels.

  • 2. Relaxation: Self-tinting lenses by ZEISS for eyes sensitive to light

    Are you particularly sensitive to light? You simply have to reach for your sunglasses faster than others. Even though the sun is barely peeping out from behind the clouds, you already find seeing strenuous. Self-tinting lenses can be a wonderful vision aid to reduce the strain on your eyes, as they adapt to the respective light conditions almost infinitely. In weak sunlight, they do not become fully dark like sunglasses, so that you can still see well in spite of the darkening.

  • 3. Less strain: Self-tinting lenses for a long day with changing light conditions

    You have had a long working day. You wear spectacles and have to move between outdoors and indoors frequently for your job. Changing spectacles all the time is frustrating and you often forget or do not have a hand free. Your eyes become strained and have a burning sensation in the evening. For you, self-tinting lenses are no luxury, they can be an important tool - even if your vision problem is minor. Your spectacles quickly change from normal spectacles to virtual sunglasses as soon as you change your workplace from indoors to outdoors - and vice versa. You have the right optical tool for every job, and your eyes will appreciate that.

  • 4. Clear vision: Self-tinting lenses for people with active and sporty lifestyles

    Are you active or sporty? The weather doesn't always cooperate, or the light conditions change frequently during sporting activities. You have no time to change your spectacles. Self-tinting lenses mean that you are ideally equipped for any light conditions that occur right from the start. Your PhotoFusion prescription spectacle lenses change their tint from clear to dark and dark to clear quickly. At the same time, they protect your eyes against the harmful solar UV-A and UV-B rays, while the best thing is that they improve your vision contrast and reduce glare.

  • 5. Child-friendly: Self-tinting lenses for children's sensitive eyes

    Children's eyes are even more sensitive to UV rays than adult eyes, as they are still developing and let in more light. As a result, children actually need daily UV protection for their eyes. If your child wears spectacles, it can be advisable and far more convenient to give your child spectacles with self-tinting lenses. That way you can be sure that your child is protected against harmful solar UV-A and UV-B rays around the clock and can still see clearly and without strain in every light situation, without having to juggle two pairs of spectacles.

  • 6. Limitless at all distances: Progressive self-tinting lenses

    One set of spectacles for all situations: Just as progressive spectacles can save you the trouble of constantly having to switch your reading glasses for your spectacles, so can self-tinting lenses save you constant switching between sunglasses and normal spectacles. Losing, forgetting or not knowing where to put your second pair of spectacles are now a thing of the past. Concentrate on the moment, and enjoy it – thanks to optimal vision in all light conditions.

  • 7. Instead of contact lenses: Self-tinting lenses for contact lens wearers

    Your contact lenses – whether daily, monthly, annual or multifocal lenses – are your best friends. But there are situations where you need spectacles. However, you still want to be as free and active as before, e.g. during sporting activities. Sports spectacles with curved and self-tinting lenses can become your best training partners. Whether light or shade, you always have the right tint, UV protection, and can see with more contrast while experiencing less glare. You only need one vision aid for relaxed vision.

  • 8. Fashion-conscious: Self-tinting lenses by ZEISS for all spectacle frames

    The times when self-tinting lenses looked old-fashioned and frumpy are long gone. Modern self-tinting lenses, like ZEISS PhotoFusion, are available in natural, modern colours - just like normal sun lenses. Self-tinting lenses can also be ground to fit any modern frame, like frameless spectacles or spectacles with curved lenses, so that you can live out your fashion taste fully.

  • 9. Mobility: Self-tinting lenses for travelling

    Especially when travelling, we want more flexibility and relaxation. Accordingly, self-tinting lenses can be a great travelling companion.

    However, you should bear in mind that most of the UV rays which activate self-tinting lenses are blocked by cars' windscreens, which means that the prescription spectacle lenses do not darken as much there. Although PhotoFusion prescription spectacle lenses offer a certain protection against glare in cars, we still recommend wearing "real" sunglasses during long journeys with significantly changing light conditions (e.g. through tunnels).

    Photochromic prescription spectacle lenses also react to temperature differences. That means that self-tinting lenses darken less in bright sunlight when outdoor temperatures are high. As a result, we recommend carrying sunglasses in southern countries in particular.

  • 10. Protection: Self-tinting lenses for medical reasons

    Do you often suffer from eye inflammation, chronic conjunctivitis or dry and sensitive eyes? Maybe you should protect your eyes against bright light and UV rays in particular. Prescription spectacle lenses which offer permanent UV protection and adapt to the light conditions can be a real benefit for you. Your ophthalmologist or ophthalmic optician can help with your decision.

ZEISS PhotoFusion "…so much better than what I've worn before.

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Oh, the Photofusion is kind of like having an automatic transmission in your car. It is just for you, you don't worry about it, you don't think about it, you just put it and drive and go. Right now ZEISS is kind of like...they got it. They are so much better than what I've worn before. I have a girlfriend and every time the sun comes out she puts on her sunglasses. When she wants to read she puts on her reading glasses, when she wants to drive at night she puts on her driving glasses. That would drive me crazy. So with this one pair of glasses, they save me a lot of money, they make my life easier, they reduce my stress and they‘re just very natural to wear. I don‘t even notice that I have them on.

Paul Hawker,
Glasses Wearer, USA

Learn more about ZEISS PhotoFusion

Fast dark. Fast clear: Self-tinting lenses by ZEISS

Are you looking for a new, favourite pair of glasses?...


Self-tinting spectacle lenses: comfortable and relaxed vision for everyone

BETTER VISION asked Volker Gahr – the Senior Product Manager responsible at ZEISS for ZEISS PhotoFusion – to describe the key features of modern photochromic lenses.


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