Polarized lenses: what are they for?

We have all experienced the sensation of glare that occurs when sunlight reflects off flat surfaces such as sea or lakes, snow, sand or asphalt. Even if you wear sunglasses, shielding from this visual effect may not be sufficient in the absence of polarized lenses . But let's go in order.

What is polarized light

We speak of polarized light when light waves that reflect on flat surfaces become concentrated and change their orientation. In particular, the horizontal reflections that can arise create a dazzling effect that alters vision, creating unnatural contrasts, and in the long run tires the eyesight. Natural sunlight is only slightly polarized by passing through the atmosphere, but if reflected it can become blinding (mirror effect); this can be quite dangerous in certain situations, such as driving a vehicle or going down the ski slopes.

Ultimately, polarized light causes a general reduction in visibility in the direction of the reflecting surface , a distortion of colors due to light reverberation and eye fatigue which, over time, exacerbates the feeling of discomfort.

How polarized lenses work

Polarized lenses are equipped with a special filter capable of blocking annoying reflected light, preventing light glare from reaching the eyes and preserving a clear vision of the surrounding environment. In fact, polarized sunglasses block horizontally reflected light , allowing only vertical light to pass through.

The filter can be applied to lenses of various colors and also to prescription lenses, stopping up to 99% of polarized radiation.

When polarized sunglasses are needed most

Based on what has been previously described, it is clear that the use of polarized lenses is particularly suitable when driving or carrying out outdoor activities, especially in the mountains or at the seaside. Snow, water and sand are in fact the most reflective surfaces.

In daily city life, polarized lenses are less necessary, indeed they could create some discomfort when viewing LCD (liquid crystal) or TFT (Thin Film Transistor) displays used for computers, tablets, smartphones, etc. In fact, these screens transmit polarized light which from a certain viewing angle would be completely filtered by the polarized lenses, making it difficult, if not impossible, to observe the display.

Which polarized glasses to choose

The first recommendation is to purchase glasses with the CE mark , avoiding lenses of dubious origin or counterfeit which cannot guarantee the safety of the product.

It then comes down to choosing the color of the lens which can influence visual comfort in different situations of use.

Gray polarized lenses are the most suitable in the presence of direct and very intense light and the presence of a lot of glare (for example on snow) because they allow for greater clarity of vision and definition of contrasts. On the contrary, green lenses are ideal for contexts with changing brightness, while brown ones (even in the variant that tends towards pink) are the most versatile, with excellent performance in all environmental situations.

Finally, it should be kept in mind that the polarizing filter in itself guarantees only partial protection against ultraviolet rays, and therefore a specific UV filter should always be combined to ensure the complete well-being of our eyes.

So, polarized lenses yes or no?

On the one hand, polarized lenses are more expensive and in some circumstances can hinder correct vision, for example if you observe certain types of displays (as already explained), or if you look through some car windshields or motorbike helmet visors.

On the other hand, there is undoubtedly greater visual comfort in all other situations, because thanks to the attenuation of the light glare, vision becomes clearer and the colors purer and more lively even in the absence of intense lights; the greater perception of contrast improves the definition of the images. But of course, the most obvious advantage is the absence of glare in the presence of strong sunlight and very large reflective surfaces, with a significant reduction in eye fatigue over time.

One last piece of advice: for all lenses, but in particular for polarized ones, it is important to use soft cloths, perhaps in microfibre, to clean the glasses, avoiding paper tissues and improper cloths from scratching the lenses and damaging the polarizing filter.