How to check sunglass lenses. Choosing sunglasses, methods for checking the quality of glasses and the effectiveness of protection. Sunglasses frames.

Sunglasses are important tool in protecting the health of your eyes and surrounding skin. When choosing glasses you need to pay attention to three important qualities: level of eye protection, comfort and style. Sunglasses must provide protection from ultraviolet radiation contained in the sunlight which contributes to the occurrence of eye diseases.

UV protection

It is recommended to purchase sunglasses with lenses that block 99-100% of UVA and UVB radiation. The label of sunglasses must contain the words UV 400 or 100% protection against ultraviolet rays. UVA rays are long waves of UV radiation; 95% of them reach the Earth and act in any weather in all climate zones. UVB rays are medium wavelengths of UV radiation that reach only 5% of the Earth's surface, but are more powerful and dangerous to the skin and eyes than UVA rays. UV rays from sunlight can be harmful to both the skin and eyes and increase the risk of developing cataracts, which lead to decreased vision; under their influence degeneration occurs macular spot eyes. Macular disease, although treatable, is completely incurable. Photokeratitis - sunburn of the cornea, which is also known as snow blindness, also occurs when proper eye protection is not used.

Sunglasses not only protect your eyes from ultraviolet radiation and your skin from premature aging, but also prevent the development of melanoma.

Glasses, like sunscreen, can be worn whenever you are outside, all year round. They are especially important for children, as their eyes are most vulnerable to sunlight. Eye damage from ultraviolet radiation accumulates over a lifetime.

Light transmittance of lenses

The amount of light that reaches the eyes through eyeglass lenses is measured as a percentage of visible light transmittance and is most often referred to as “VLT.” Light transmittance depends on the color and thickness of the lens, the material from which it is made and the presence of additional coatings on it.
There are 5 groups of lenses depending on the amount of visible light transmission:

• Untinted lenses that transmit 80-100% of light are combined into a group called “zero”. Glasses with these lenses may slightly reduce your exposure to UV radiation in cloudy weather.
• The first group includes lenses that transmit 43-80% of light. Such lenses can be used for glasses that are used in not very bright sun.
• The second group - lenses with a light transmittance of 18-43% are suitable for use in sunny days in autumn and spring, as well as in summer.
• Lenses belonging to the third group can transmit 8-18% of light. Glasses with such lenses are suitable for wearing in summer; they protect the eyes well from UV rays and do not interfere with vision; they are the best option for drivers.
• The fourth group includes tinted lenses with a light transmittance of 3-8%. These lenses are recommended for use during holidays in hot countries or during ski resorts. But due to their low light transmission, they should not be used for driving. They usually have the mark “High UV-protection” or “High UV protection” on the label.

Lens material

Sunglass lens materials are very diverse and differ from each other in a number of characteristics.

• Among the most popular sunglass lens materials are the following:
• Polycarbonate is a strong, lightweight plastic that is highly impact resistant and has good optical clarity, but has slightly less optical clarity than glass or NXT;
• Glass is a durable material with high optical transparency and clarity, it is heavier than plastic, it breaks when hit, but is scratched less.
• NXT polyurethane - has the highest impact resistance, excellent optical transparency and clarity; light and flexible material.
• Acrylic is an inexpensive alternative to polycarbonate and is best suited for occasional sunglasses. Acrylic is less durable and less optically transparent than polycarbonate or glass, and allows some image distortion.

Lens Color (Shade)

All sunglass lenses are tinted because tinting reduces the overall glare of light and improves image clarity. The choice of glasses color depends on personal preference, but it is also important to consider some characteristics of the colors.

• Gray shades lenses reduce brightness without distorting color.
• Brown and amber lens tints reduce glare. The brown shade itself is considered neutral, i.e. it reduces the overall brightness of the light without significantly distorting colors. Wearing glasses with brown lenses helps reduce eye fatigue in moderately bright conditions.
• The yellow tint of the lenses provides excellent depth of perception; lenses of this color are ideal for skiing, snowboarding and other winter sports. They also increase contrasts in difficult lighting, thereby distorting colors to a greater extent.
• Green tinted lenses reduce glare and provide good contrast between objects.
• The pink tint of the lenses provides good visibility when dim light and increases contrast (ideal for skiing and snowboarding in cloudy weather). Pink lenses increase the visibility of objects against blue and green backgrounds, making them ideal when driving or being outdoors.

Lens coatings: types and functions

Polarizing and anti-reflective films are used to coat lenses to reduce glare - reflections of light perceived by the eye from the surfaces of certain objects, such as water, asphalt, etc.

There are several methods for polarizing lenses, which differ in the optical qualities and cost of glasses. An inexpensive option is the actual film coating; A more durable, high-quality and expensive option for polarization is the insertion of a polarizing filter between the layers of the lens. Newest Hi-tech polarization spectacle lenses allow polarizing components to be evenly distributed in the lens; their addition occurs while the lens material is in a liquid state (liquid plastic or glass). With this polarization technology, the filter and lens are connected without the use of glue, which means that the glasses have high optical quality.

Protective coatings on sunglasses are a thin film that makes the lenses scratch-resistant. Most often, protective films are applied to plastic lenses, since they are to a greater extent more susceptible to mechanical damage than glass.

Mirror films are a type of reflective coating. A film with a mirror effect is applied to the outer surfaces of sun lenses; reduces glare by reflecting most light that hits the surface of the lens.

Water-repellent coatings, or hydrophobic ones, are used to ensure that water does not linger on the lens in the form of droplets.

There is also an anti-fog coating, but it is not often used on sunglasses.

Sunglasses frames

Used in the manufacture of sunglasses various materials frames Metal frames are more expensive and durable than plastic frames, but can be uncomfortable in high temperatures as they heat up quickly and intensely. Nylon frames are impact-resistant, lightweight and durable, but generally non-adjustable. Frames made of acetate plastic can be different colors, but the material is not flexible and not durable.

When choosing glasses, you should pay attention to the frame material, since some metals used in their manufacture are allergens and are not suitable for everyone. Allergenic metals include nickel and chromium, which is also used in electroplating. Titanium frames are recognized as non-allergic, but there are many alloys of titanium and other metals, so when choosing, you should give preference to frames made of pure titanium.

Checking the quality and convenience of a specific model

Be guided only appearance and the contents of the label when choosing sunglasses is incorrect: you must wear glasses to find out how comfortable the model is and suits you: the glasses should not press or press on the bridge of the nose, the frame should fit snugly to the nose and ears, but not injure them.

The weight of the glasses should be evenly distributed between the ears and nose. Lightweight frames are preferred to avoid excessive friction.

Glasses should not interfere with your blinking; contact between eyelashes and lenses is unacceptable.

Tilt your head down to check how well the glasses are fixed: when tilting, the glasses should not slide onto the tip of the nose and fall off. If your glasses are too tight, ask the seller about the possibility of adjusting the frame fastenings. If after adjustment or if it is impossible you feel discomfort, then you should not buy glasses. To reliably protect your eyes from harmful ultraviolet radiation, choose glasses that have a close-fitting shape (on the sides), since Sun rays may penetrate your eyes at an angle. When choosing glasses, you should also pay attention to the size of the lenses: your eyelids should be hidden from sunlight.

You can check the quality of the lenses by wearing glasses and looking around in them: the colors should not be significantly distorted, for example, White color should remain white and not change to another color, only the appearance of light shades is permissible. Take a small object and look at it small parts, for example, read the inscriptions on a coin. After taking off your glasses, compare your perception of this object: if you could not distinguish the contours and see the details while wearing glasses, this means that the sunglasses are of low optical quality.

Today, optics stores offer many different UV radiation testers that allow you to check the level of light transmission of lenses in the UV range. Accurate data is provided by tests using spectrophotometers, which reveal the level of light transmission at a specific wavelength, and also take into account the optical power of the lens when measuring.

You can independently check the polarization of your glasses in the following way: through the lens of the glasses, look at the LCD monitor, display of a mobile phone, smartphone or payment terminal monitor; turn the lens 90 degrees relative to the monitor: if the image you see through the lens has darkened or become completely black, then the glasses are highly polarized; if the image has not changed, the glasses are not polarized.
You can also test your glasses for glare protection: put on your glasses and look at the glossy surface that refracts light, then take off your glasses and compare the sensations. In glasses with anti-glare effect, you can look at glare without squinting, and it is easier and easier to see the object creating the glare.

Responsibly approach the choice of glasses, take into account all the characteristics: the quality and coating of the lenses, the comfort of the frame, the level of light transmission and protection from UV rays, as well as style and design. Sunglasses are a means of protecting the eyes and the skin around the eyes, as well as a bright accessory that should be harmoniously combined with your image.

IN Lately I've heard the phrase polarized glasses. What does it mean: another marketing ploy or something really practical. After all, more and more buyers prefer glasses equipped with polarizing filters.

What is polarization

Speaking in simple words, polarization is the direction of light, which can be vertical or horizontal. If vertical rays allow the eye to detect colors and shades, then horizontal ones interfere with this. Because of them, we see glare instead of objects or cannot see clear contours.

If horizontal light waves are eliminated, the image becomes clear and bright. You can not only see what shines in the light, but also see objects through storm and rain, muddy water and fog. This discovery makes polarizing filters indispensable in some professions and hobbies.

Why do you need polarized glasses?

Several decades ago, the technology for making polarizing filters was very complex. They were used only for certain jobs in production, film and photography that required precision and the absence of light interference. Today the technology is much simplified and allows you to create lenses High Quality, thin and durable.

Polarized glasses have become a commodity. First, their benefits were appreciated by drivers, pilots, and then by people involved in fishing. Today, such glasses are widely used in many sports (skiing, rowing, cycling and others).

Many buyers are interested in glasses that have polarizing filters not only because they are fashionable, but also good for the eyes. For example, if a person suffers from sensitivity to light or has to spend a lot of time open sun, then for him the best solution will be just such an acquisition.

It is worth noting that such a filter does not protect against ultraviolet radiation, but only against glare and other interference. But thanks to it, the load on the retina is reduced and vision does not deteriorate.

Where to buy and how much do these glasses cost?

If you decide to purchase polarized glasses, then head to a specialized store. You won’t find the product on sale on the same shelf as regular sun-protection models. good quality. At an optical store, you will not only get useful glasses, but you will also be able to test them on the spot. The seller will give you a guarantee and, in case of defects, will exchange the goods.

The price of polarized glasses can range from several hundred to thousands of rubles. The cost depends on the technology used to make the lenses. If the filter is placed on the outside of the glasses, they will be cheaper and less durable.

It is better to purchase models where the filter is built into the lens, that is, located in the middle. To accomplish this task, two very thin lenses are made, a polarizing filter grid is placed between them, and then they are glued together. This ensures durability and long service life of the glasses.

Check the goods without leaving the checkout. In the store itself you can find out how high quality the glasses you are going to buy are.

How to check in store:

1. In good retail outlets Sellers have special indicator strips that will help you find out the quality of the polarizing filter. Look at the indicator through your glasses and you will see an image that you cannot see without them.
2. Take the second polarized glasses, place them opposite each other, and then rotate one 90 degrees so that the centers of the lenses coincide. If they darken in places where they coincide, then the glasses are of high quality; if the visibility has not changed, then no.

What should those who have had polarized glasses for a long time do and cannot check them in the store? There are several tricks for this case.

How to check at home:

1. Turn on your monitor, TV or smartphone, as long as it has an LCD display. Point the glasses at it and turn it 90 degrees again. If the filter is of high quality, then the image through the lenses should no longer be visible.
2. If you have an aquarium at home, look at the bottom through your glasses. A good filter will allow you to see what is there even through muddy water.

These methods are enough to understand what kind of glasses you have, regular or polarized.

What can lens color tell you?

When you walk into a store, you can be confused by the variety of such models. To choose the most suitable one for you, pay attention to the color of the lenses. He will talk about the main properties of glasses:

Blue lenses. Designed for those who need to work on water. They eliminate glare even from a large surface area;

Yellow lenses. Designed to improve visibility in cloudy conditions or dark time days;

Pink lenses. They increase the clarity of the image, with them you can see what is difficult to see with the normal eye;

Black lenses. Insert into regular sunglasses that do not transmit ultraviolet light.

Now, when you go to the store, you won’t get confused and choose a color based on your personal taste and preferences.

Advantages and disadvantages

To decide whether it is worth purchasing polarized glasses or doing without this feature, you need to weigh all the pros and cons of the purchase. After all good model will cost a lot of money, and a cheap one will not give the desired effect.

Advantages:

• no glare or glare;
• the eyes do not get tired from prolonged strain;
• create protection from direct sunlight;
• indispensable in certain types of activities;
• Help people with photosensitivity.

Flaws:

• when the sun is at its zenith, glasses cannot protect;
• high price;
• if you have vision problems, glasses will not correct them;
• dim the light from signs on the road, side lights and brake lights;
• may distort the distance;
• are inconvenient if you use a navigator or other devices with an LCD display, as they darken the image on it.

Using glasses with polarization is undoubtedly convenient, and if you take into account the small disadvantages, you can avoid the problems that they cause.

What to do to make your glasses last a long time

If you want your purchase to please you for many years and help protect your eyes, then follow the rules for storing glasses with polarized lenses:

1. Buy a quality case that is durable on the outside and coated on the inside. genuine leather or cloth.
2. To clean the lenses, use a soft cloth; it usually comes with your glasses. Do not rub them on clothing or rough fabric.
3. If the glass becomes very dirty, wash it with soap and water. detergents use is not recommended.
4. Do not place glasses with the lenses facing down, as this will cause scratches. To prevent your glasses from accidentally falling, secure them with a chain.

The quality and durability of polarized glasses depends on the manufacturer. Companies that respect their customers always sell goods through chains of pharmacies and opticians, so you should not save money and buy them in dubious stores, but rather go to specialists.

Video: How to check the polarization of glasses using a monitor