Self-darkening lenses
Sun-darkening lenses, also called photochromic lenses, automatically change tint: they activate when exposed to light and lighten when you go back indoors. They are a convenient option if you go in and out multiple times a day. The choice is confirmed during the eye exam.
Before you start
Lenses that darken in the sun are technically known as photochromic lenses. These are lenses that change their tint according to the light: indoors or at night they are transparent; when you go outside in the sun they automatically darken, and when you go back inside they regain their transparency.
They are an alternative to wearing two different pairs of glasses (one normal prescription and one pair of sunglasses) or the typical gesture of constantly changing them. With a single pair of glasses, you cover both situations.
How They Work
The change in tint occurs due to the reaction of molecules incorporated into the lens when exposed to ultraviolet (UV) radiation from the sun. Upon receiving UV, the lens darkens. When moving away from the UV source, it lightens again.
They are only activated by sunlight (direct or indirect). Artificial indoor lights do not trigger the change, which is why they regain full transparency upon returning indoors.
The activation speed when going out into the sun is usually a few seconds. The lightening process upon returning indoors is a little slower, between one and several minutes depending on the type of lens and ambient temperature.
When they usually fit
They usually fit when:
- · You go in and out of outdoors several times a day.
- · You prefer a single pair of glasses instead of switching between prescription and sunglasses.
- · You work or study indoors but frequently go outdoors (breaks, meals, shops).
- · You frequently drive on routes with changing light (tunnels, shade, direct sun).
- · You seek the convenience of not having to change glasses.
What to consider
Photochromic lenses are convenient, but they have limitations you should be aware of:
- · Temperature. They activate less and more slowly in heat. In cold weather, they darken more and take longer to clear.
- · Car windshield. They activate less behind a car windshield because the car glass filters out much of the UV that triggers the change. If you drive a lot with the sun in your face, specific sunglasses are often a better fit.
- · Clearing speed. Clearing when returning indoors takes a little longer than activation. In very well-lit indoor spaces with natural light, they may remain slightly dark for a while.
- · Lifespan of the effect. Over the years, the ability to darken and clear gradually loses intensity. This is a natural phenomenon of this type of lens.
What Miller & Marc photochromic lenses offer
Our photochromic lenses combine:
- · Lenses from Essilor Group, the world leader in ophthalmic lenses.
- · Fast activation when exposed to sunlight (a few seconds) and progressive clearing indoors.
- · 100% UV protection when activated.
- · Anti-reflective and hardened as standard, included in all prescriptions we make.
- · Treatment integrated into the lens. It's not a surface coating: it's part of the lens, so it won't scratch or peel with use.
- · Adaptation to your prescription (myopia, hyperopia, astigmatism, presbyopia) and also available in single vision, progressive, and reading lenses.
They are available in three base shades: gray, brown, and green. In store, we will show you the differences before you decide.
How we choose it with you in-store
At Miller & Marc, the decision is confirmed during the free visual examination. A registered optician assesses your prescription, your usual habits (how much time you spend outdoors, if you drive a lot, if you work outside), and what type of photochromic lens can truly benefit you.
If you're torn between photochromic lenses and separate sunglasses, we'll discuss it together in-store.
Frequently Asked Questions about Photochromic Lenses
How long does it take for a photochromic lens to darken?
Modern photochromic lenses activate within seconds of exposure to sunlight. The clearing process, when returning indoors, takes a bit longer, between one and several minutes depending on the type of lens and ambient temperature.
Do photochromic lenses work in the car?
Behind the car's windshield, they activate less because the car's glass filters out a good part of the UV that triggers the color change. They darken somewhat, but not as much as outdoors. If you drive a lot with the sun in your face, specific sunglasses usually fit better.
Do photochromic lenses protect from UV?
Yes. When activated, they filter 100% of ultraviolet radiation. This is one of their main functions, not just the change in tint.
Can they be combined with a prescription?
Yes. Photochromic treatment can be applied to prescription lenses of all types: nearsightedness, farsightedness, astigmatism, presbyopia. It can also be combined with progressive and reading lenses.
How long do photochromic lenses last?
The lens itself lasts like any other. The ability to darken and lighten loses intensity over the years; it is a natural phenomenon. Most people change their lenses due to a change in prescription before noticing this loss.
Can photochromic lenses be added to my current glasses?
Yes. It can be added with the next lens change, keeping the frame. The frame does not change, only the lenses.
