With the multitude of shapes, sizes and colors that exist on the market, it is often not easy to choose your sunglasses. However, there are some criteria that you must take into account in your choice; in particular the UV protection index.
The UV protection is the main criterion in the choice of your glasses. There are 4 categories of protection:
The glasses of category 0 answer only an aesthetic and fashion need. So avoid them.
The glasses of category 1 to 2 are suitable for use in mid-season
Category 3 offers excellent protection. These glasses are suitable for use at the beach during the summer or for skiing.
Category 4 glasses are reserved for cases of high solar luminosity. This corresponds for example to mountaineers.
The type of lenses
In the case of sunglasses, it is important to choose lenses that do not allow UV rays to pass through and at the same time, can respect the colors as faithfully as possible and thus offer you excellent optical quality. There are several types of filtering lenses.
This is a glass that is very resistant to scratches and offers good optical comfort. The only drawback is that it is quite heavy and not very resistant to shocks. It is not used much anymore.
The organic glass
It is still called CR39. It is a light glass, which filters between 98 and 100% of UV rays. But it scratches easily but offers a good resistance to shocks.
It is the most resistant but also the lightest glass. It is particularly suitable for sports sunglasses because of the 100% UV protection it offers.
Tinted lenses filter out some of the light rays that make up the light. This helps to reduce the discomfort of vision
These are dark glasses that adapt to the intensity of the light to the sun protection. Ideal if you often change environment.