Everyone knows the dangers of the sun to the skin. But what are the risks to your eyes? Most people wear sunglasses primarily for comfort against glare. And yet the eyes also fear the sun. Why? What to protect yourself from? What's the real risk?
The benefits of the sun on our health
It is essential to our physical and mental well-being. However, we all now know that it can also have harmful effects on our skin: skin aging, melanoma, etc. According to a study by the National Association for the Improvement of the View (LASNAV 2012) 37% of respondents believe that ultraviolet radiation is more harmful to the skin than to the eyes. In the same study, 84% of French people own sunglasses, compared with 68% for their children.
Ophthalmias, cataracts and DMLA (a retina disease leading to the eventual loss of central vision): the long-term consequences of too much exposure to the sun are nevertheless very real.
A little bit of scientific explanation about light
To see correctly, we need the light and its rays whose reflections inform us about our environment. However, our eye does not distinguish all the waves sent by the sun but only those between 380 and 780 nanometers (nm), with an almost infinite variety of colors. The danger to our eyes comes not from these waves but from those above and below these limits. In other words, danger comes from invisible rays !
Below 380 nm, we find the UV group, classified in three categories: A, B, C. The most dangerous for our eyes are UVA because they reach our lens. In children, whose lens is transparent, ultraviolet can even touch the retina. The lens acts as a natural UV barrier; absorbs UVB. Finally, the vast majority of UVCs are blocked by ozone in the atmosphere, but a tiny part still manages to touch the cornea.
On the other side of the visible spectrum, above 780 nm, are the infrared; But with them, no surprise, because you immediately feel a burning sensation.
Many tend to forget the harmfulness of the rays of blue light. They are found throughout the day in daylight and even more with a cloudless sky. To combat it, we all have a stock of melanin, a natural pigment found in our skin, hair and eyes. This amount of melanin decreases with time. Blue light primarily attacks the retina, accelerating its aging and blurring vision.
What are the sun's risks to our eyes?
The main danger comes from UV, because even if they violently attack our eye, we feel nothing. At least first. Our eye, like other parts of our body, has the ability to renew certain cells that have been affected by significant exposure to these rays. But this stock of cells is not inexhaustible and the eye can soon become vulnerable. Many years later, therefore, the price of sustained exposure to the sun is paid, especially when one has not been protected during childhood.
UV can gradually penetrate the various barriers of our eye (crystalline, retina...) causing serious damage. In just an hour or two of high sun exposure, corneal ulcerations may appear and turn into chronic keratitis (inflammation of the cornea). UV damage to the lens can trigger cataract (l-opacification of the lens) with five to ten years ahead.
How can you protect yourself from the sun?
As with your skin, common sense means that you protect your eyes as soon as you are exposed to the sun. If the UV is present as soon as the sun rises, you should be even more careful between noon and 2 p.m., when it is in the zenith. At this point, ultraviolet rays are the most numerous and offensive.
Of course, when we talk about sun protection, we immediately think about summer holidays. But we must not lower the guard in winter, in the mountains. On the contrary! The higher the altitude, the higher the amount of UV: it is estimated that an additional 10% UV is required every 1000 meters. Moreover, snow reflects 85% of these rays. Our eyes are therefore under severe strain! In the mountains, the light is such that the effects of UV can be expressed immediately: this is what is called snow eye disease, a cornea pathology.
Who needs to protect himself from the sun?
Everyone needs to protect themselves. In children, the lens remains transparent until 10 or 12 years of age. So UV rays penetrate deeper into the eye. From an early age, get your children to wear glasses. Especially as there are some models made especially for them that take into account their morphology. In adulthood, if our eyes can in part defend themselves against UV, suitable protection allows us to keep our sight capital to the maximum and delay the appearance of eye diseases.
Older people are also very sensitive, especially those who have already undergone certain operations, such as cataracts.
A suitable sun protection depends primarily on your activities: work or outdoor sports, regular mountain trips, water activities... Don't hesitate to take a full look at all your sun exposure periods. Based on this information, your eye doctor and optician will determine the best sun protection according to your needs and eye health.
