Sunglasses - useful or not?

Excessive exposure of human eyes to ultraviolet radiation can cause serious consequences such as eyelid burn, corneal burn, and retinal burn. Ultraviolet rays destroy the cells of the lens of the eye, resulting in cataracts.

To protect your eyes from such harmful effects of sunlight, sunglasses can help. Not so long ago, only glasses with glass lenses could retain a large amount of ultraviolet rays, but science and optical industry do not stand still. Today, special coatings for plastic lenses have been invented: anti-reflective and antistatic, photoprotective and photochromic.

They come in single or multi-layer and provide excellent protection for the eyes. But not all plastic sunglasses are harmless: cheap plastic from an unknown manufacturer, tinted in an incomprehensible way, does not give UV protection.

On the contrary, the pupils of the eyes, being behind the dark lenses of such glasses, dilate, and the sun's rays as a result damage the retina more than in the case when a person is without glasses at all. That is why it is important to heed the recommendation to select and buy sunglasses only in trusted places. Degree of sun protection. The lenses of glasses, depending on the amount of light they let through, are divided into several categories.

Category 0. Glasses transmit one hundred percent of light and at the same time retain ultraviolet rays. The lenses are mostly transparent, there are translucent lenses. Glasses from this group are used as a fashion accessory in the dark or for sports when there is no bright light.

Category 1. The glasses transmit up to eighty percent of light and are ideal for wearing in variable cloudiness and low sunlight, the lenses are low-darkening.

Category 2. These are medium tinted glasses, they let in about forty percent of light and are suitable for wearing in not too bright sunlight.

Category 3. Glasses with dark colored lenses (brown, gray, dark green, and others) that transmit less than twenty percent of light and protect well from the bright sun. They also provide good protection in the mountains, by the sea, in tropical zones.

Category 4. Eyeglasses with heavily darkened lenses that allow virtually no sunlight to pass through. They are worn in extreme conditions when the light is unusually bright. It is not recommended to drive a car while wearing glasses of this group. The color of the lenses of sunglasses. Quality glasses with colored lenses do not change the view of the surrounding world, do not distort colors, but only slightly change the shade.

Fake glasses will lead to loss of orientation and distraction, fatigue, and their prolonged wear can even create mental problems. Glasses with colored lenses. Ophthalmologists say that the most comfortable lens color for the eyes is dark gray and dark green. Green lenses have the ability to filter out the most ultraviolet light.

And the lenses of gray-colored glasses allow the most realistic perception of the surrounding shades of color. Yellow and pink lenses are good for wearing in cloudy weather, they improve visibility and increase contrast. But you should refrain from wearing glasses with blue and blue lenses, as they make the lens of the eye expand.

Chameleon glasses. The lenses of these glasses are able to adapt to the amount of sunlight: they darken in bright light and lighten in darker light. In low-quality glasses, both lenses may darken differently. Quality glasses, however, will not darken in artificial light.

Glasses with gradient lenses. The color of the glass goes from a darker shade to a lighter shade so that the upper part of the glasses is darker than the lower part. Glasses with such lenses are comfortable to wear in many situations and will be the best choice for motorists. It is also recommended for car drivers to wear glasses with polarizing lenses, which are able to block sunlight reflected from horizontal surfaces (for example, from water or fields covered with snow).

So sunglasses with polarizing lenses are great for wearing in high altitude areas or fishing and provide good protection from the blinding rays of the sun.

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