Sunglasses are a fashion accessory, but above all aprotectionfor your eyes.
The quality of the lenses is therefore essential when choosing your glasses.
differentcategoriesglasses exist; below you will find their specificities and how to choose them.
When we are exposed to the rays of the sun, the pupils of our eyes dilate to filter the sunlight to our retina. Often, this natural filter is not enough. Sun lenses therefore protect you from several lights; the visible and the invisible.
The sun emits different types of ultraviolet (UV) rays. These are UV A and UV B.
Invisible to the eye, ultraviolet rays are nonetheless a danger in the event of overexposure, they could seriously damage your eyes.
TheUV Aare the most dangerous for the eyes, since they reach the lens in adults and can reach the retina in children.
As toUV Bthey are absorbed by the lens in adults.
There are also Infra-Red rays which can be dangerous for the eyes in extreme conditions (high mountains, desert...) by causing drying and a rise in temperature.
Protection of your eyes with glassesblocking 100% of UVis therefore essential.
The dangers of visible light are glare, fatigue, discomfort and possible temporary loss of vision. This light does not always have the same intensity depending on the place, the climate, the relief... it is therefore for these reasons that there are different filtration indices or protection categories to protect your eyes from these dangers.
There are five categories ranked on a scale from 0 to 4, depending on the increasing percentage of light filtered;
CATEGORY 0 - PROTECTION INDEX:
These lenses only filter up to 19% of sunlight. This category of protection is the lowest and is not suitable for prolonged exposure to strong sunlight.
CATEGORY 1 - PROTECTION INDEX:
These lenses filter between 20 and 57% of sunlight. Category 1 lends itself well to limited sunshine, for example gray or overcast skies.
CATEGORY 2 - PROTECTION INDEX:
These lenses filter between 58% and 82% of sunlight. Suitable for average sunshine but outside the summer period when the ambient light is generally at its maximum.
CATEGORY 3 - PROTECTION INDEX:
Recommended: this category 3 is the one most often recommended for sunglasses. These solar lenses filter between 83% and 92% of the sun's rays and are perfectly suited to contexts with strong sunlight, whether during the summer (beach, sea) and winter (mountain and ski) periods.
CATEGORY 4 - PROTECTION INDEX:
These category 4 lenses are extremely effective. They filter up to 97% of sunlight. Used in extreme conditions such as mountaineering in high mountains or on glaciers where the reverberation is very strong. Please note, this category is prohibited for driving because it affects vision and color perception.
Among the types of lenses there are also polarized ones which also add extra protection and comfort for your eyes. Our articlexxxxxxx will give you more explanation on their usefulness.