The degree of sunlight transmission and the level of protection from ultraviolet rays are two key indicators that determine the quality and scope of a particular model of sunglasses. So, let’s look at how to choose sunglasses by type of protection.
The degree of protection of sunglasses
There are four levels of protection for sunglasses. Level «0» means that these glasses can only be worn on cloudy or overcast days, as they let in 80% to 100% of the sun’s rays. «1» is suitable for weak sun, such as a summer evening. The degree of transmission of rays by lenses with this marking is 43 — 80%. Glasses marked «2» are suitable for strong sun, you can choose them if you decide to spend the summer in the city. They block most of the sunlight, passing from 18% to 43% of the rays to the eye. «3» is suitable for relaxing by the sea, where the sun is already very intense. The percentage of transmission in them is only 8-18%. The most protected points have level «4». In such lenses, your eyes will be comfortable even at a ski resort, as they let in from 3% to 8% of the sun’s rays.
Information about what kind of protection sunglasses should have is worth looking at the label, which also contains information about the manufacturer. Any high-quality model should have such labels. In addition, it is worth paying attention to the fact that the higher the protection, the darker the lens. So, glasses with a protection level of «4» cannot even be used when driving a car, they are so dark.
Sunglasses with UV protection
How to determine the degree of protection of women’s sunglasses, in addition to information about light transmission? To do this, there is another parameter on the label — data on how many ultraviolet rays (UVA and UVB spectrum) this or that model passes. 
In total, there are three types of points, depending on this parameter:
- Cosmetic — such glasses practically do not delay harmful radiation (transmission rate 80-100%), which means that they can be worn when the sun is not active.
- General — glasses with this marking are perfect for use in the city, as their glasses reflect up to 70% of the radiation of both harmful spectra.
- Finally, to relax by the sea or in the mountains, you need to pick up glasses marked High UV protectionas they reliably delay all harmful radiation, which multiplies many times when reflected from water.