Transitions, Reactions & Photochromic Lenses: What’s the Difference?
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If you’ve ever found yourself squinting into the sun while wearing your prescription glasses, or fumbling for your sunglasses the second you step outside, you’ve probably looked into "lenses that change colour."
But then you hit the jargon: Transitions? Reactions? Photochromic? It sounds like three different products, but at Sapphire Optics, we like to keep things clear. These are all names for the same brilliant technology—lenses that stay clear indoors and automatically darken into sunglasses when you step into the light.
At a glance:
Transitions, Reactions, and photochromic lenses all refer to light-reactive lenses that darken in sunlight and return to clear indoors. Sapphire Optics offers this technology across a range of lenses, fitted in-house for everyday convenience and UV protection.
The Name Game: Why the Different Terms?
It’s a bit like calling every vacuum cleaner a "Hoover."
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Photochromic: This is the scientific, technical name for the light-reactive technology itself.
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Transitions®: This is a famous brand name of photochromic lenses (like Nike is to trainers).
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Reactions: This is the term we often use at Sapphire Optics to describe our high-quality light-reactive lenses.
By using the term Reactions, we can source the very best technology from world-leading manufacturers like Zeiss, Hoya, and Essilor in our Manchester lab, ensuring you get incredible performance and UV protection without paying extra just for a brand name.
How Do They Actually Work?
These lenses are embedded with special molecules that react to UV light.
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Indoors: The molecules stay "closed," and your lenses look like standard, clear glasses.
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Outdoors: The moment they hit sunlight, the molecules "open up," darkening the lens to protect your eyes.
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Coming Back In: As the UV levels drop, the lenses gradually return to their clear state.
Why Choose "Reactions" Lenses?
Our customers across the UK love them because they offer the ultimate "one-pair" convenience. They are perfect for:
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Busy Lifestyles: Moving from the office to the school run without swapping frames.
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Constant Protection: They provide 100% UV protection, even when they are only slightly tinted on an overcast day.
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Prescription Flexibility: We can add "Reactions" technology to almost any pair in our Mens, Womens, or Unisex collections.
FAQ
Do they work inside the car?
This is the most common question we get! Most standard photochromic lenses don't darken fully behind a car windscreen because the glass blocks the UV rays needed to "activate" them. If you do a lot of driving, you might prefer a dedicated pair of Prescription Sunglasses.
Do they turn into "full" sunglasses?
They get very dark—usually around an 85% tint in direct sunlight. While they are brilliant for everyday use, if you are heading to a bright beach or hitting the ski slopes, a pair of dedicated category 3 sunglasses might still be your best bet for total light blockage.
Can I get them with a thin lens?
Absolutely. If you have a higher prescription, we can fit High-Index Reactions lenses in our lab to keep your glasses looking sleek and feeling light.
Will I get my old lenses back?
Yes! If you are using our Reglaze Only service to upgrade your current frames to Reactions lenses, we always return your original lenses with your finished order.
Helpful Reading:
Prescription Sunglasses: Everything You Need to Know
Can You Put New Lenses in Old Frames? Reglazing Explained
