Choosing your sunglasses: tips

Sunglasses go hand in hand with sunshine and holidays.
But do you know how to choose them properly?

Are sunglasses useful?

The primary purpose of sunglasses is to protect your eyes from ultraviolet rays (UVB). Prolonged exposure to UV rays can damage the surface of your eyes and their internal structures, potentially leading to cataracts, inflammation of the cornea (photokeratitis) or photoconjunctivitis (inflammation of the conjunctiva).

Aside from this health risk, wearing sunglasses eases the strain on your eyes when exposed to a very bright environment, and will prevent you from being dazzled if you suddenly step into full sunlight.
Finally, glasses (prescription and sunglasses alike) also have an aesthetic function, given the choice of frames, lens type, colour, etc.

How do you choose good sunglasses?

• Choosing the lenses: choose lenses that block as much UV radiation as possible (ideally 100% of UV rays, or UV absorption up to 400 nm). UV absorption doesn't depend on the colour of the lenses, nor on their price, but rather on how the lenses have been treated to block UV rays. Beware: the fact that you're wearing tinted lenses doesn't necessarily mean those glasses protect you from UV rays!
• Choosing the filter category: depending on how much light they filter, sunglasses are divided into 5 categories. The category therefore refers to how dark the tint of the glasses is. This category is often shown next to the “CE” quality mark or on the packaging. Category 0: absorbs 0 to 20% of light. This type of glasses performs poorly, and will mostly have an 'aesthetic' value. Category 1: absorbs 20 to 57% of light. Sufficient protection in overcast weather or hazy sunshine. Category 2: absorbs 58 to 82% of light. Sufficient protection in sunny weather with limited sun exposure (e.g. in the city). Category 3: absorbs 83 to 92% of light. Ideal protection for prolonged sun exposure, ideal for outdoor activities in summer. Category 4: absorbs 93 to 99% of light. Only to be worn when exposed to exceptionally strong light (e.g. at the seaside or in the mountains). Don't wear glasses of this category while driving a vehicle! Category 3 or 4 glasses are the darkest. Tip: Choose the category that suits you based on how you'll be using your glasses.

Other selection criteria

• The colour of the lenses: some tints absorb light more easily than others, or alter vision or colour perception to varying degrees. Grey is the most neutral tint. Brown-coloured lenses absorb light strongly but slightly distort colours. Yellow lenses reduce the intensity of the blue sky but distort light more. Blue or pink glasses are the least suitable tints given their poor performance.
• Sunglasses suited to your prescription: do you wear glasses to correct your vision? It's possible to combine corrective lenses with sun protection. However, take into account the type of protection you want (see the categories above). Some lens types automatically adjust to light levels (they're "photochromic"), but this adjustment doesn't always happen immediately.
• Children: young children's eyes are more sensitive than adults' and of course also need to be protected in bright light. Don't buy your children cheap sunglasses that offer little or no protection, or glasses that don't fit their face. Glasses that are too big will let UV rays through around the edges of the frames.
• Comfort: make sure the glasses don't hurt and are suited to your face.
• Sturdiness: buy glasses that are sturdy enough: on holiday, glasses are sometimes put through their paces!
• Quality: don't buy glasses just anywhere (be wary of street vendors or souvenir shops). Favour the advice of an optician instead. Buy glasses bearing the CE mark.
• Your personal taste: it will often have the final say...

What about contact lenses?

Contact lenses with UV filters are handy for those who don't want the hassle of glasses on their nose (e.g. athletes). However, be careful, as these lenses don't protect the eyelids and the area around the eyes.

One last tip: Glasses are important for protecting your eyes, but don't forget to protect your skin with good sunscreen!
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