Photochromic lenses are lenses that change their transparency depending on the brightness of the light, more precisely, the amount of ultraviolet radiation. First, they are for people with poor eyesight who wear glasses and represent the most versatile solution. They are automatic sunglasses that protect the eyes in bright sunlight and are transparent indoors or at night.
Features of use
Now that we have figured out what photochromic lenses mean. Let's talk about their features. At first glance, such optical products are the optimal choice for any person. They provide comfort indoors and outdoors, while a person doesn’t have to make any effort to see well.
However, photochromic glasses have their nuances of use.
- Lenses don’t darken and brighten instantly. It’s the key advised indicator to pay attention to when ordering glasses. On average, the time required for photochromic elements to react is between 30 seconds and 5 minutes. The lenses begin to change color immediately. You will not be in a situation where the glasses remain completely black indoors. The smooth change in light transmission is comfortable for the eyes, so buyers usually don’t complain about this feature.
- Lenses may darken and lighten unevenly. When darkened, areas of a different color will remain.
- The degree and speed of darkening depend on the ambient temperature. The reaction is faster in warm weather and slower in cold weather. At temperatures above 30°C, the lenses don’t darken completely, but by 90-95%, which can cause discomfort to residents of the southern regions. On the contrary, in the cold, the glasses give out their maximum, which isn’t always convenient when it’s partly cloudy or walking through the forest with constantly changing lighting.
How to choose photochromic glasses
Knowing what photochromic glasses mean and how they work, you can make a list of factors when choosing such optics.
- Material of manufacture. In most cases, plastic is the best choice – it’s lightweight, resistant to mechanical stress due to several protective layers, provides uniform darkening, and fits any frame.
- The degree and speed of dimming. You need to pay attention to the maximum and minimum indicators – for example, if the minimum degree of dimming of the glasses is 17-18%, they will be a little dark in the room. It can cause discomfort. As for the speed of darkening and lightening, for modern brands, the indicator fluctuates between 1 and 5 minutes – naturally, the faster the better.
- UV protection. When choosing inexpensive models, check if the lenses have such an option: you need to protect your eyes from harmful radiation to the maximum.
- The ability to darken in the car. Thanks to special production technologies, the lenses react not only to ultraviolet light but also to the length of the beam, so they provide driving comfort.
- Design. If you look at the photos of photochromic glasses the variety of lenses is simply amazing. Today, there are not only traditional gray, green, and brown, but also color, and even mirror ones. There are plenty to choose from to look stylish and modern.
How long do photochromic lenses last?
The service life of photochromic lenses is from 2 to 5 years. Gradually, light absorption indicators are deteriorating. However, manufacturers are constantly working to increase the life of lenses. Secondly, ophthalmologists recommend that people with refractive errors undergo vision tests and, if necessary, change glasses every 2-3 years.
How to care for photochromic lenses
Despite the most advanced protective coatings, lenses with a photosensitive layer can be sensitive to mechanical and thermal influences. Therefore, it is important to store, operate, and care for them. To prolong the life of the glasses, you should keep them in a case. Remove products with two hands, and don’t pull with one side. If you use improvised means to clean photochromic lenses, they can ruin their surface. Use only special solutions, special microfiber cloths, or disposable wet ones for optics. For milder care, it is recommended to choose sprays. Don’t wipe the lenses with simple wet wipes. Their impregnation can permanently damage the coating. Try not to expose the products to high temperatures and mechanical stress.
Modern photochromic lenses can last quite a long time. In any case, their service life, as a rule, is not less than that of similar lenses but without photochromic. Over time, there may be some weakening of the dimming function. But this doesn’t take such proportions as to affect the quality of operation. Rather old lenses have to be replaced with new ones due to a change in prescription or because protective coatings become unusable as a result of the prolonged and not accurate operation.
