Hello my dear readers! The height of summer, people go on vacation. Everyone wants to swim in the sea, sunbathe in the sun. And you forgot to buy such an important accessory like sunglasses? I know, I know, to many this issue very seriously, cherish and care for his beloved, valuable and expensive thing.
But a lot of people who leave before you ran into any shop where there are cheap sunglasses, chose what to face, happy and satisfied! Let us look at this issue. What to consider when buying this accessory?
Impact of ultraviolet rays on the organ of vision?
Which sunglasses to choose? Friends! UV rays in fact is the enemy No. 1 for our eyes. When the sun shines, we feel happy. And we were not aware that from the point of view of physics, the body is irradiated with ultraviolet rays. They, these same rays are divided into three types:
- UV-C – wavelength ultraviolet rays of this range is the shortest, so they are extremely dangerous to humans. But, fortunately, these waves do not reach the Earth, because it is completely absorbed by atmospheric ozone layer.
- UV-b also have short enough wavelengths (280-315 nm). Partially retained in the layers of the atmosphere, but have a high damaging effect. As UV-b waves have an effect on the eyes. They damage only the surface layers of the eyeball, not penetrating into the depth of tissues. Usually, if you have a rest on the sea, severe burns of the conjunctiva and cornea get. But if you are high in the mountains at ski resorts, where the terms of the white snow and the sun, you can easily get a sunburn, called photokeratitis. Will experience severe pain, lacrimation, blepharospasm, erythema of the mucous membranes of the eyes and eyelids. It may even be a temporary loss of view – “snow blindness”.
- UV-A is the length of the waves directly adjacent to the visible spectrum and is 315-390 nm. These ultraviolet waves are less dangerous. The trouble is that they have the ability to penetrate deeply into the eye. Damage the lens and the retina. And in recent years scientists have discovered that there are waves, the length of which is 400 nm. Called them blue rays. They also penetrate deeply into the environment of the eye and have a high damaging effect.
You will not notice any changes in the view. The harmful effects of ultraviolet waves UV-A accumulated in a lifetime. This leads to increased risk of cataracts, destroys the retina and causes blindness in old age. So fans lie and bask in the sun need to protect their eyes from solar radiation. This is easy to do using the correct choice of protective glasses from the sun!
How to choose sunglasses?
Outdoors on a Sunny day, our eyes perceive the visible spectrum, which has a wavelength more than 400 nm. The smaller the wavelength refers to the invisible UV radiation. It is from their harmful effects we need to protect their eyes with sunglasses.
Good quality sunglasses with 99% to protect your eyes from UVB and 95% of UV-A radiation. This fact is the most important criterion when choosing sunglasses. Which ensures the protective properties of the sunglasses? The material from which made the lens and application to the surface of various additives that improve the quality of protection.
What happens if we all decide to save and not to buy expensive sunglasses, but tinted plastic lenses? It’s very simple. Under the darkened lenses your pupils dilate. It is clear to everyone – in-the-dark pupils always dilate!
All powerful stream of ultraviolet waves gush in our eyes. It’s awful! Extremely dangerous, especially deep tissues of the eyeball – the retina and the lens. It is better not to wear glasses with plain plastic lenses. Because we all know that the brighter the light falling on the eye, the more narrowed pupils. Narrow pupils create at least some protection of the internal media of the eye from dangerous UV radiation.
What spectacle lenses to choose – glass or plastic?
Lenses made of glass, effectively protect the eyes, not letting the UV rays. They indefinitely retain a presentable appearance, they are not scratches are formed. But they are heavier plastic, pressure on the nose. And there is always the danger that they may break. Therefore, children certainly do not buy them.
Sunglasses, made of acrylic or polycarbonate plastic, and with a variety of additives are not worse than glass. Moreover, they are lightweight, very rigid, not shatter like glass. The operation is very reliable.
Polarized lenses: Eyeglasses with such lenses are important to fishermen. For those involved in water sports. They block reflected from the water light and emerging on the water glare. Thereby increasing the quality and contrast of the image.
Polarized lenses buy drivers, people working in the wilderness, climbers, climb the snow-capped peaks. In all these cases, there is a blocking reflected from smooth surfaces bright light, such as the highway roadbed, sand dunes, pristine white snow.
Photochromic lenses: They are very convenient for people having defects in visual acuity and forced to wear corrective glasses. If lenses these glasses to apply the photochromic coating, it will effect points “two in one”. Indoors the lenses of the glasses are transparent, and when entering the street, will be dark. The brighter the light, the more clearly will manifest their protective effect against UV rays. Beauty!
Mirrored lenses: One option sunglasses are mirror. Create them by spraying on the surface of colored glass or plastic, silver crystals, and also of zirconium oxide and titanium. These lenses do not get hot from the scorching rays of the sun very well eliminate glare. They are popular among motorists, athletes. Suitable for people travelling through the desert, making cruises.
The choice of sunglasses lens color.
Currently available glasses various colors: brown, yellow, gray, green, orange, black, red, purple, pink, blue. The intensity of the color plays no role. You can buy bright lens, but with a very high quality coating is completely impervious to the sun’s rays. In other words, which color of lenses to choose is a matter of taste.
Only for people with certain types of professions and important for athletes color lenses. Now scientists have developed special recommendations for the choice of color sunglasses lenses in each sport. Yellowish tints provide the best contrast. They are suitable above all for skiers.
Still, for long-term wear glasses with colored lenses have limitations. To look at the world constantly through glasses of one color is tiring to the eyes and psyche.
What sunglasses to choose for a trip to the sea or ski resort, and just to put on bright, Sunny days – your choice! The main thing to remember is that you care about the direct protection of the eyes from the dangerous UV radiation. And then give the fashion and image creation.