How to choose them? According to what criteria?

2024-07-21 13:39:40

Nowadays, we can find sunglasses at very affordable prices in markets, department stores, online and even at gas stations, which raises the logical suspicion of users. One of the most common questions opticians are asked is: “Will they protect me well?” » While these types of lenses typically provide only minimal UV protection, the visual quality they provide is disastrous sexual.

Optical shops are establishments run by health professionals whose Professions are regulatedtherefore all their products must meet minimum standards: Marking CE wait British CA. Optometrist health professionals are trained to provide guidance based on a client’s visual requirements and facial features.

In addition to the “CE” mark on sunglasses, in France, the Directorate General for Control of Competition, Consumption and Fraud (DGCCRF) also stipulates Practical advice Choosing the Right Sunglasses, Editor’s Note.

Supervision and protection

Sunglass lenses considered “personal protective equipment” According to current European regulations. Additionally, the regulation specifies five classes of solar filters. Class 0 transmits 80% to 100% of the light. Category 4, on the other hand, only allows 3% to 8% of light to pass through, making it unsuitable for driving. Category 3 is the most commonly used as it is suitable for most situations and is suitable for driving.

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The darker the lens, the more protection it provides? No, the level of light absorption you choose depends more on your purpose. Category 4 is suitable for bright environments (mountains or deserts), but visibility may be reduced in other conditions.

Regardless of this factor, all glasses that meet the standards provide protection from UV rays.

visual quality

Wearing sunglasses feels like “impairing your vision.” In fact, tinted glass is a selective filter: it lets one type of radiation pass through and attenuates another. Therefore, it is important to explain some concepts related to vision.

Vision is a measure of “what we see.” It is assessed by asking subjects to read increasingly smaller letters that appear on a screen. Approximately 100% level (become one vision 10/10 or 10 out of 10, editor’s note) is ideal. However, this test was conducted with black text on a white background (high contrast), so changes in visual quality under other lighting conditions were not taken into account.

Second, contrast sensitivity is defined as the ability to distinguish an object from its surrounding background. It is more difficult to distinguish black letters on a gray background than black letters on a white background.

Finally, refractive errors can affect vision and contrast sensitivity, including nearsightedness, farsightedness, and astigmatism. When you have one of these conditions, wearing non-prescription sunglasses may cause your vision to be worse than without glasses.

Depends on the color of your lenses

That being said, we will now address another common question in optics: does the fact that the glass has a certain color change or improve the protection? Actually, This chroma affects the perception of contrast and brightnessbecause each color is attenuated by a different wavelength.

So while gray will attenuate all wavelengths, hues like brown or green won’t flatten the absorption curve. therefore, visual perception Brown tones tend to be very light, gray tones are very dark, and green tones are more natural.

Organic lenses or mineral lenses?

But it’s not just color that affects visual quality: it’s also important to check the composition of your lenses. If the most common glass is made of organic materials (plastic), there are also models of mineral glass on the market, which are mainly made of silica, soda and lime.

There are differences between the two materials. Organic lenses are lighter and more impact-resistant, while mineral lenses are more scratch-resistant and have less dispersion. The optical properties of the latter therefore enhance the visual quality of the wearer.

What about polarized lenses?

Polarized lenses reduce glare by blocking light that reaches your eyes at an angle after being reflected from surfaces such as roads or water. They are especially recommended for driving and using them in marine environments.

However, their use may not be recommended in some situations. For example, they block light from the screen, making it dim or even completely black, requiring the screen to be rotated for better visibility. They are also not suitable for winter sports because eliminating glare can make it difficult to spot ice.

Other features to consider

Finally, the following features should not be overlooked when purchasing eyeglasses:

Deterioration of sunglasses. They generally absorb about 85% of light in dark areas and about 10% of light in bright areas. They give people a feeling chic glasses, but this does not prevent them from providing adequate UV protection. If it is not recommended to use them in summer or on sunny days, then on cloudy days they can become our ally.

Mirror lenses. Their surfaces feature a new coating that reflects light and increases protection. Unfortunately, this treatment is easily damaged and scratched.

The interior of the lens is treated with anti-reflective treatment. They provide clearer vision by eliminating light reflections from the wearer’s back. They are often found in large sunglasses or models that stand out for the optical quality of their lenses.

When in doubt, we insist: ask your optician.

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