Lenses that darken in the sun? You may have already heard about them, but you are probably skeptical about the real importance of having automatic sun protection without your intervention. In fact, especially for those who wear prescription glasses, protecting the eyes from the sun can become quite a hassle. Soprattutto when you find yourself in environments that involve different light intensities, choosing whether to wear sunglasses or clear lenses can cause difficulties.
Fortunately, solutions have been developed for many years that allow for lenses that darken automatically in the sun, also known as photochromic. Thanks to particular adjustments, they become sensitive to light and change color based on the amount of UVA, UVB, and infrared rays received.
How do photochromic lenses work?
Thanks to a special treatment, photochromic lenses are coated with materials that through a chemical reaction darken or return to being transparent based on exposure to sunlight.
The reaction occurs in contact with UVA, UVB, and infrared rays. Although it seems like a recent discovery, the first experiments were even conducted in the 60s!
Gradually, technology has refined, improving aesthetic performance, comfort, and the speed of transition.
Soprattutto the speed of transition from clear to colored has been increased, achieving a complete transition from dark to clear (and vice versa) in just a few minutes.
Do photochromic lenses darken only in the sun or also in artificially lit environments?
If in the past it could happen that glasses darkened even inside environments lit by artificial light, today the lenses change color only when illuminated by the UV rays of the sun.
Wearing photochromic lenses does not cause any discomfort inside your home or in the office, the glasses remain clear and there is no noticeable difference compared to glasses with standard lenses.
Moreover, modern photochromic lenses like those created by Essilor combine darkening with protection from blue rays, essential to avoid fatigue due to excessive use of electronic devices.
Do they completely protect against UVA and UVB rays?
Just as with sunglasses, photochromic lenses have total protection from UV rays.
However, there are some specific situations in which it is advisable to use sunglasses instead of photochromic ones: when practicing outdoor sports and in situations of intense light such as at the sea or in the mountains.
In fact, when doing outdoor sports and being in places where brightness and reflected light are very strong (for example, sailing at sea or road cycling), it is advisable to wear polarized glasses that have a total degree of coverage from UVA and UVB rays.