Few of us think of sunglasses as protection against cataracts, but that's essentially what they are.
Not only letting us see better against a glaring sun, they also shield us from high-intensity UV rays, which can cause a painful inflammation of the eye and increase the risk of eye diseases like cataracts later in life.
However, when it comes to choosing the right sunglasses, the rule of thumb is not "the darker, the better". The colour of the lenses has nothing to do with UV protection, and optometrists say that darker shades of sunglasses can even lead to damage.
Sunglasses with particularly dark lenses filter out a lot of light, causing the pupils to dilate even more. When the glasses are then removed, more UV rays hit the retina, Germany's KGS association of optometrists says.
The tint of the lenses determines how well they protect from glare. The higher the value achieved on a scale of 0 to 4 -, the more disturbing light the sunglasses lenses filter out.
Category 2 is well suited to typically less harsh summers of northern Europe, for example, while category 3 sunglasses are a good choice for a holiday in the sunnier southern Europe, on the beach or in the mountains.
Category 4 sunglasses are suitable for holidays in the high mountains. However, these extremely dark lenses are not suitable for use in road traffic. Category 0 and 1 sunglasses are not as popular in summer and are best suited to cloudy skies.
But how do you know whether your sunglasses offer good UV protection? In Europe, the CE mark is a key indicator, as it guarantees that the sunglasses meet EU standards. The glasses have a UV filter that keeps most of the harmful rays away from the eyes. Some models also carry the UV400 test mark.
When buying sunglasses in other countries, you may need to check local regulation, as it may be unclear just how well sunglasses actually protect the wearer from UV rays.
Although some people find micro sunglasses more stylish, they do not offer sufficient protection. The lenses should reach at least as far as the eyebrows for optimum protection from the sun, optometrists say. The brackets should ideally be slightly wider so that less sunlight hits the eye from the side.