What are photochromic glasses

Photochromic sunglasses are glasses whose lenses automatically adjust to light conditions. They have a variable (reversible) transmittance that changes depending on the intensity of UV or visible light. 

The lenses of these glasses darken when exposed to more UV radiation (light) and become almost clear again when indoors or in reduced light.

How do photochromic lenses work?

Photochromic (self-tinting) lenses contain special molecules that react to UV light. When the lenses are exposed to sunlight, the molecules change their structure and the lenses gradually darken. Once the UV radiation is reduced (for example, by moving indoors), the reaction is reversed and the lenses lighten again. The whole process takes only a few seconds to minutes, depending on the specific type of lens and the intensity of the light (UV). In general, the more modern types of self-tinting lenses (e.g. Transitions® Gen S™, ColorMatic® X) react very quickly. 

Interestingly, some types of self-tinting lenses react to the amount of UV radiation, while other, special types react to the amount of light hitting the glasses.

An absolute novelty is Transitions ColorTouch — self-tinting lenses in trendy shades (Sapphire, Ruby, Emerald, Amethyst, Amber) that do not tint to a completely clear state in the room, but retain a light colour tone that adds a distinctive style to each wearer and gives the glasses an exclusive look.

How do photochromic lenses work in winter?

The winter season is specific for photochromic lenses and often surprises even experienced users in terms of functionality. Photochromic glasses are especially recommended for winter sports, where they combine: 

• anti-glare protection,
• UV radiation
• and mechanical eye protection against wind and snow. 

However, it should also be said that in winter, photochromic lenses may be slower to return to their clear state after going indoors. Again, this is due to the lower temperature, which slows down the back reaction of the molecules. 

Advantages and disadvantages of photochromic glasses

Advantages of photochromic glasses

• Eye protection — Photochromic lenses automatically regulate the amount of light entering the eye while providing permanent protection from harmful UV rays. This helps to protect not only the vision itself, but also the eye area from the long-term negative effects of UV radiation. 
• Convenience — You don’t have to constantly change sunglasses with different tint intensities or take them off. You will appreciate this especially when playing sports. 
• Overall money saving — Thanks to their adaptability, photochromic glasses can replace multiple types of glasses.
• Reduce eye fatigue — The smooth change of lens tint helps reduce eye strain during transitions between different lighting conditions (light to shade).

Disadvantages of photochromic glasses

Although photochromic glasses offer high comfort and are a very versatile tool, they are not the ideal solution for everyone and every situation. From a professional point of view, it is important to know their limits so that expectations match reality.

• They don’t always achieve maximum darkening — Photochromic lenses do adjust to light intensity, but in most cases they don’t achieve as dark a tint as conventional sunglasses.
• Limited functionality for drivers — Car windscreens largely filter UV radiation, which means that some lenses in the car get little or no tint.

Tip: However, Transitions® Drivewear® provide optimum vision experience and colour contrast when driving as they respond to both UV and visible light. The lens colour and level of darkening adjust to the light conditions while driving. 

• Delay in colour changes — The transition between clear and dark is not instantaneous. For some types of photochromic lenses it can take tens of seconds to several minutes (affected by temperature, light intensity or age of the lenses). 
• Higher purchase price — Photochromic lenses are more technologically complex than conventional clear lenses, which is reflected in their price. 

Photochromic bicycle glasses

When cycling, the eyes are exposed to rapidly changing light conditions. The great advantage of self-darkening lenses is that you can use them both during sunny days and when it is cloudy. When cycling, you need to protect your eyes not only from glare and UV rays, but also from insects and foreign bodies, which photochromic glasses do very well (+ you can wear them when the sun is low because they are almost clear). 

In the eye studio we recommend glasses to all cyclists:

• with a wide enough field of view,
• with quality optics without optical distortion,
• adapted to the specific shape of the face.

The reaction speed of photochromic lenses is also very important in sports. Modern sports photochromic lenses can adapt to light changes within seconds, which significantly increases both comfort and safety. 

Photochromic bike glasses with diopters

There are various solutions for cyclists with dioptric correction — from dioptric sports lenses to glasses with a dioptric insert. Each option has its own specifics and is not suitable for everyone.

During a personal consultation, we help you choose a solution that:

• maintains optical quality even at higher diopters,
• will not restrict peripheral vision,
• will be compatible with the specific sport frame.

For cyclists, we often have to deal not only with the colour of the lenses themselves, but also with their shape and curvature to avoid distortion of the image in the peripheral vision, which is essential for safety when riding.

In our offer you will find a large number of models with self-tinting lenses. For example Evil Eye E 049/75 6500 S or Evil Eye Trace Pro with photochromic lenses VARiO clear automatically and continuously adapts its colour to the light conditions. In low solar activity they are only lightly coloured, in intense sunlight they are dark grey. Their colour intensity ranges from grade 1 to grade 3 (lightly coloured to darkly coloured), light absorption ranges from 28 – 86% (i.e. light transmittance 72 – 14%). 

An absolute and revolutionary innovation is the Evile Eye 051 esense nextelectronic cycling glasses, which thanks to the integrated LCD module adapt to the current light conditions in an extremely short time — only 0.6 seconds.

Photochromic Polarized Driving Glasses

Driving places high demands on your eyesight, such as rapid changes in light, low sunlight, glare from the road and dashboards. Photochromic polarized glasses can be a very beneficial solution for drivers, but it is important to properly understand their operation and limitations. 

By partially or completely blocking UV radiation from the windows or windscreen, the tinting effect in rooms or cars is minimal or non-existent with conventional photochromic lenses. Therefore, there are special types of photochromic lenses for drivers that:

• react not only to UV but also to visible light,
• with self-tinting polarising lenses, the polarisation effect is only active from a tint above 50%,
• are able to tint behind the windshield,
• Polarising lenses may limit the visibility of some screens (e.g. “head up display”).

However, these variants have specific characteristics that must be taken into account when making the choice.

Tip: ColorMatic® Dark are a new product from the global lens manufacturer Rodenstock. ColorMatic® Dark combines high darkening, consistent performance at higher temperatures and coloration even behind the car windshield. Outdoors, the lenses darken up to 90%, eliminating glare and reducing reflections, while remaining nearly clear indoors, without the presence of UV rays. They provide constant visual comfort and convenience on the road. 

Which lenses to choose for the driver?

These include Transitions XTRActive, which tint in the car but are not polarizing, and DriveWear, which tints in the car and is also polarizing. The biggest advantage of photochromic polarizing lenses for drivers is that, in addition to filtering out normal light, they also eliminate distracting glare from horizontal surfaces. 

Transitions XTRActive Polarized are polarized lenses that reduce glare and provide the wearer with better vision when viewing reflective surfaces such as water, wet pavement, snow or glass. 

How to choose the right photochromic glasses?

When choosing photochromic glasses, it is important to consider, among other things:

• What activity do you want to use the glasses for the most (e.g. sports, casual wear, driving)?
• What colour shade should the lenses be (e.g. brown, grey, green, even purple)?

Keep in mind that the colour of the lenses affects not only the appearance but also the perception of colours. Brown shades tend to brighten, grey shades dim. 

Types of spectacle lenses	Glare reduction = polarization	Colouring in the interior	Darkening in the car	Driving at night	Available colours
Transition XTRActive	No	clear with a hint of colour	changing — category 2	No	grey
Transitions XTRActive Polarizing	excellent (weaker in the car)	clear with a hint of colour	changing — category 2	No	grey
Transition Drivewear	excellent	100%	changing — category 2	No	green-brown
Transitions GenS	No	Clear	limited — rather clear	Yes	grey, brown, green + 5 other colours
Transitions Color touch	No	fine colouring (gradal or tinted)	fine colouring	No	5 colours (gradal or tinted)

Frequently Asked Questions (FAQ)

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Sources

• https://is.muni.cz/th/woixb/Materialy_brylovych_cocek_a_jejich_povrchove_upravy__1_.pdf
• https://www.transitions.com/cs-cz/
• https://www.colormatic-lenses.com/#colormatic-dark

*Transitions® and the Transitions® logo are trademarks of Transitions Optical Inc. used under license by Transitions Optical Limited.
© 2025 Transitions Optical Limited. Photochromic activity may vary with different colours and lens cap materials. It is also affected by temperature and UV aging.
Vogue Eyewear® rim, Transitions® eyecups in Ruby. Select frames may not be available for purchase.