What is a photochromic lens? Why is it useful when I play sports? What are its advantages and disadvantages? Can you make photochromic lenses for prescription? In this article, we will answer all these questions and give you all the information you need to know about photochromic lenses.
Take stock of your sports practice
When you want to equip your pair of sports glasses with corrective lenses , it is better to think carefully about the tint of the lenses that you are going to order.
To do this, you need to ask yourself a few practical questions that will help you make the right choice:
- What is my main use for this pair of glasses?
- What time of year do I use them?
From these 2 questions naturally follows the choice of your glasses. Indeed, defining the main choice is the major question.
We all have multiple sporting activities during which we want to use our sports glasses, but of course, there are compromises to be made: whatever your choice, your lenses will not perform well in all situations , so it is important to know the main use you will make of your sports frame.
Let’s add to the equation the time of year when we practice our main activity: Is it rather summer when the days are very long and the weather rather sunny or all year round in all seasons, including winter when night falls at 4:30 p.m.?
To meet all the needs of athletes, one type of lens has become established in the sports eyewear landscape in recent years: photochromic lenses!
What are photochromic lenses?
As their name suggests, these are lenses that darken with light, or more precisely with the quantity of UV received (and not with brightness as one might sometimes think).
These glasses are covered with pigments containing photosensitive molecules that are activated by UV and whose physicochemical reaction is reversible. The greater the amount of UV, the more the chemical reaction occurs. As soon as the amount of UV is reduced, the number of colored molecules decreases, thus lightening the glass until it becomes perfectly transparent at nightfall.
The term 0-3 indicates the categories of lenses in the deactivated state (Category 0, i.e. transparent without tint) to the activated state (Category 3, the standard category for sunglasses). There are also other variants of photochromic lenses that can range from category 1 to 3 or from category 2 to 4 for example for certain specific uses.
As you will have understood, photochromic lenses are the most versatile lenses that can be found, including for indoor or night-time sports (long-distance cycling, for example).
So does the perfect glass exist?
Not quite! Photochromic lenses will cover 90% of your needs but there will be times when these lenses will reach their limits:
- Temperature-sensitive lenses : And yes, the photochemical reaction is slowed down and limited by rising temperatures; in other words, the hotter it is, the less well they work. In the middle of a heatwave at 40°C in the sun, your lenses will barely reach category 2, while in the mountains at 0°C, the lenses will happily reach category 3, or even flirt with category 4!
- Lenses that don’t darken in the car : It’s quite simple, the windshield of our cars filters almost all UV rays, so the glasses cannot darken due to a lack of UV rays… A good reason to switch to a convertible!
At METAOPTICS, we have opted for the best. This is TRANSITIONS 8 technology. The lenses activate and deactivate quickly and the operating dynamics are very durable (4 to 5 years with the same performance). They reach 80% of their maximum tint in 30 seconds .
You can even opt for adding a mirror effect which will slightly darken your lenses by 2 to 3% but which will allow you to match your glasses to your sports outfit!
Advantages and disadvantages of photochromic lenses:
Benefits
- Perfect protection against the sun’s UV rays
- A versatile and economical lens: with the purchase of a single pair of photochromic lenses, you will be as well protected at night as during the day and in all weather conditions. No need to buy several pairs of lenses.
- The speed of changing the tint of photochromic lenses is only a few seconds when you suddenly change your environment.
Disadvantages
- Versatile but not perfect: photochromic lenses allow you to have lenses that adapt to many situations during your activities, but they will show certain limitations on specific uses.
- Does not work under the car windshield: photochromic lenses react to the sun’s UV, not to brightness. Since the windshield blocks UV, photochromic lenses remain transparent when you drive.
The little extra
Photochromic lenses are available for all corrections. Whether you are short-sighted, presbyopic, astigmatic, etc. Thanks to METAOPTICS, you can equip your sports glasses with photochromic lenses to your vision, whatever your prescription, even progressive lenses!
If you would like more information on progressive lenses, check out our article: Progressive lenses on sports glasses: good or bad idea?
