Photochromic lenses darken on their own in sunlight and turn clear again when you step back indoors. If you wear prescription glasses and spend the day moving between home, the office, the car park and the street, they can save you from carrying and swapping two pairs.
They are not right for everyone, though. How dark they get depends on the weather, the temperature and where you are, and in a car they often stay lighter than people expect. Knowing how they behave before you order is the easiest way to avoid disappointment.
How Photochromic Lenses Work
A photochromic lens contains light-sensitive molecules, either mixed into the lens material or held in a thin layer on its surface. When ultraviolet (UV) light reaches them, they change shape and start absorbing part of the visible light, which is what makes the lens look darker. When the UV fades, the molecules return to their original form and the lens clears.
So it is mainly the amount of UV, rather than how bright the day looks, that drives the change. On a clear summer day around midday the lenses darken noticeably. Early in the morning, late in the afternoon or in the shade they stay lighter.
Darkening is usually quick, and most people notice it soon after stepping outside. Fading back is slower. Once you are indoors, it can take a few minutes for the lenses to become fully clear again. The exact time depends on the lens type, the maker and the temperature, so any single figure would be misleading.
Even when clear, most photochromic lenses filter UV. That said, UV filtering is now built into many ordinary spectacle lenses as well. What sets photochromic lenses apart is the change in tint.
Why Heat and Cold Change the Result
Temperature matters almost as much as sunlight. In cold weather photochromic lenses get darker and take longer to clear. In hot weather they darken less and clear faster, because the molecules flip back to their clear state more quickly when they are warm.
İzmir shows both sides of this. On a scorching July afternoon the sun can be dazzling, yet your lenses might not reach the depth of tint you had hoped for. Winter turns things around. The sun sits lower and its UV is weaker, but the cold helps the lenses stay dark, so on a crisp, sunny January morning in Kemalpaşa they can be darker than you expect and slower to clear when you walk into a shop or café.
Snow makes the effect stronger still. Snow reflects UV and the air is cold, so up at Bozdağ on a winter day photochromic lenses can turn very dark. On a hot summer beach, by contrast, the same lenses may be noticeably lighter than a pair of sunglasses. If you plan to spend much of the long İzmir summer outdoors, it helps to know this from the start.
Do Photochromic Lenses Darken in the Car?
Most photochromic lenses do not darken fully inside a car. The reason is the windscreen, which blocks most of the UV in sunlight. Because the lenses rely on UV, they get very little signal behind the wheel and stay clear or only lightly tinted.
Some photochromic designs respond to part of the visible light as well as to UV, and these can darken partially in the car. Even then, the tint behind the windscreen is usually lighter than it would be outdoors, and lighter than a good pair of sunglasses.
So if your main aim is to shade your eyes while driving, photochromic lenses on their own may not be enough. The road between Kemalpaşa and Bornova runs roughly east to west, so driving east in the morning or west in the evening can put a low sun straight in front of you. For a daily drive like that, a separate pair of prescription sunglasses is often more comfortable, and our prescription sunglasses guide covers the options.
There is one more thing to keep in mind. If you have been walking in the sun and then get into the car, the lenses can stay dark for the first few minutes. That is worth allowing for late in the day or when you pull into a covered car park. At night photochromic lenses are close to clear, so they behave much like any other prescription lens. If oncoming headlights bother you, have a look at our night vision and night driving guide.
Photochromic vs Polarised Lenses
People often mix up photochromic and polarised lenses, but they do different jobs. A photochromic lens reduces the overall amount of light, getting darker as the surroundings get brighter. A polarised lens is designed to cut the horizontal glare that bounces off the sea, wet tarmac or the bonnet of a car.
Most photochromic lenses are not polarised. A darkened photochromic lens makes bright sun more comfortable, but it will not cut the glare on the water the way a polarised lens does. A few makers offer special lenses that are both photochromic and polarised, although the choice there is narrower.
If you are looking for glasses for sailing, fishing or water sports around Çeşme or Urla, a polarised lens is usually the better fit. For someone who moves between indoors and outdoors around town all day, photochromic lenses tend to be more practical.
Prescriptions, Lens Types and Colours
Photochromic versions exist for most prescription lenses. They are most common in single vision lenses, which correct either distance or near vision. Progressive lenses come in photochromic versions too, so someone who relies on one pair for both distance and reading can keep the same glasses on outdoors. Our guide to progressive lenses explains how those work.
Office lenses are made for desk work and are not meant for walking around outside. Whether a photochromic version exists depends on the range, and we can look into it with you in the shop.
Colour options vary between makers. Grey, brown and green are the most common. Grey keeps colours looking natural, which is why many people choose it. Some wearers find that brown tones make contrast feel sharper. Green is another common choice. A few makers also offer brighter fashion colours.
Zeiss, Hoya, Essilor and Transitions all make photochromic lenses, and their ranges differ in how dark they get, how quickly they clear and which colours they come in. Photochromic lenses are also made in different refractive indices, so with stronger prescriptions it is often possible to combine a thinner lens with the photochromic effect.
Coatings deserve some thought as well. An anti-reflective coating on a photochromic lens reduces reflections, especially light bouncing off the back surface towards your eye. Our article on eyeglass lens coatings explains what each one does.
Who They Suit, and When They May Fall Short
Photochromic lenses make the most sense for people who go in and out of buildings many times a day and want to keep their prescription glasses on the whole time.
- People whose work takes them between shops, offices and the street
- Anyone who would rather not carry prescription glasses and sunglasses separately
- Walkers, parents on the school run and anyone popping out to the market for short spells
- People whose eyes tire quickly in bright light and who want some relief through the day
In some situations they may not be enough on their own.
- Drivers who want a dark tint, since the lenses usually stay light behind the windscreen
- People who spend long hours by the sea or on wet roads, where a polarised lens may be more comfortable
- Anyone whose job needs clear vision the moment they step from sunshine into a dim room, as clearing takes time
- Those who want their glasses to look completely clear indoors at all times, because some lenses keep a very faint tint
If sensitivity to light has started recently and comes with pain, redness or blurred vision, it is not a lens problem. Please see an eye doctor the same day. Even if the sensitivity is painless but ongoing, it is sensible to have an eye doctor check it before choosing lenses for it.
Can They Go Into Your Current Frame?
In most cases, yes. If your frame is in good condition, you can have photochromic lenses fitted without buying a new one. Since the lenses are being replaced anyway, it is a good moment to have your eye doctor confirm that your prescription is up to date, and we can make up your new lenses from the doctor's prescription. Our lens replacement page explains how the process works.
We recommend replacing both lenses together. If you change only one, or the two lenses come from different makers or were made at different times, they may darken to different shades. That looks odd and can feel uncomfortable too.
The photochromic effect can weaken over time. After long use the lenses may not get as dark as they used to, or may not clear fully indoors. When that happens depends on how often you wear them, how much sun they see and the type of lens. Keeping them away from harsh chemicals such as acetone or bleach, and not leaving them on the dashboard of a hot car, also helps protect the coatings.
Frequently Asked Questions
Do photochromic lenses go fully clear indoors?
Indoors most photochromic lenses look very close to clear. Some keep a very faint tint, depending on the maker and the range. If you have just come in from bright sun, it can take a few minutes for them to clear completely.
Do they darken on cloudy days?
Yes, but less. Clouds let part of the UV through, so the lenses can still darken somewhat on an overcast day. How much depends on how thick the cloud is and the time of day.
Can photochromic lenses replace sunglasses?
For short spells outdoors, many people find them enough. If you will be driving, spending the day by the sea or staying out in strong summer sun for hours, a separate pair of sunglasses is often more comfortable. Photochromic lenses darken less in the heat and usually do not darken fully in the car.
What affects the price of photochromic lenses?
The price depends on the lens maker, the range, your prescription, the lens type and the coatings you choose. To find the options that suit you, drop by the shop or send us a WhatsApp message.
Photochromic Lenses in Kemalpaşa, İzmir
At İlhan Optik, our shop in the Mehmet Akif Ersoy neighbourhood of Kemalpaşa, we help you choose photochromic lenses. We go through suitable photochromic options, Transitions in particular, based on your prescription, your frame and how your days usually go. We speak English, so feel free to ask us anything in the shop. You are welcome from central İzmir, Bornova and Buca without an appointment, and a short WhatsApp message helps you avoid busy hours. Bringing your eye doctor's prescription along makes it easier for us to see what you need.
