The radiation emitted by the sun travels through space and passes through Earth’s atmosphere before reaching us. It is then absorbed in successive stages, particularly by the ozone layer.
Of this radiation, only the rays that provide light (visible light) are perceptible to us. In contrast, the most harmful rays—ultraviolet and infrared—are completely invisible.
At low doses, infrared radiation is not dangerous. Ultraviolet radiation, on the other hand, has destructive effects that become more severe the farther it is from the visible spectrum.
There are three categories (in ascending order of wavelength): UVC, UVB, and UVA.
The most dangerous, UVC rays, are blocked by the ozone layer. UVA and UVB rays are absorbed by all eye tissues.
The lens and cornea absorb most of the UV radiation, which can eventually cause damage. Constant cell renewal counteracts this damage, but there is a cumulative effect.
Frequent exposure to UV radiation from a very young age can lead to serious retinal problems later in life. That’s why it’s so important to protect children’s eyes!
The risks exist from sunrise onward and increase significantly between 11 a.m. and 3 p.m.
Snow, water, and sand—which reflect 80%, 20%, and 10% of UV rays, respectively—are high-risk factors.
Children’s eyes are much more permeable to light than those of adults. Furthermore, their lenses do not filter out all UV rays until they are 10 to 12 years old.
In infants, UVA and UVB rays pass completely through to the retina. By age 10, approximately 60% of UVA and 25% of UVB rays reach the retina.
The harmful effects of light are even more significant in children with little melanin, particularly blond-haired, light-eyed children.
It is more dangerous to wear ineffective sunglasses that do not protect against UV rays than to not wear any at all.
In fact, in the shade created by tinted lenses, the pupil dilates, allowing more harmful UV rays to pass through.
When choosing glasses or contact lenses, ask your optician for advice and keep in mind that :
Don't confuse tint with a UV filter: only the lens material blocks UV rays; the tint only protects against glare.
The frames should be wraparound: don't put your eye health at risk just for the sake of style by wearing lenses that are too small; your glasses should not let UV rays in from above, below, or the sides.
Total protection is possible: certain coatings allow lenses to block 100% of UVA and UVB rays. This protection is essential for sensitive eyes and in conditions of high exposure.
Contact lenses have limited protection: they offer some protection against UV rays and glare, but they cover only part of the eye. The eyelids and the “white of the eye” remain exposed, which can lead to burns or conjunctivitis.