Table of contents:

What should you look for when choosing sunglasses? Usually, when choosing glasses, we pay great attention to how fashionable they are, whether they go well with the face, whether they are comfortable. Undoubtedly, these are all important factors. But there are much more essential points that must be taken into account in the first place. After all, buying fashionable glasses does not mean buying good ones.
First, let's figure it out - what are we protecting our eyes from? From the blinding sun, from the bright sunlight? Yes, many people believe that the lenses of sunglasses only protect against glare, so they choose darker glasses, especially if the summer is hot. But this is not the biggest problem. Sunglasses are mainly designed for very different purposes. Ultraviolet and infrared radiation can cause far more serious vision problems than light. When you look at the sun with unprotected eyes, the ultraviolet rays are almost completely absorbed by the cornea and lens, and partly by the retina. What can this lead to? When the rays are exposed to the cornea, it cannot be ruled out that it will be damaged. The effect on the lens, as experts believe, can gradually lead to its clouding, the development of cataracts. And if the retina also suffers, degenerative changes in the so-called macular spot are not excluded.
Infrared (heat) rays are also absorbed by the cornea and the lens, but, unlike ultraviolet rays, they act more on the retina. No wonder her burn can occur - and there are such facts - during a solar eclipse. At this moment, there is a large flow of thermal radiation, and the effect on the retina can be very strong, up to the formation of scars on it. Thus, sunglasses are not a fashion statement, but often an absolute must.

When buying glasses without a prescription, you do not know what color, what degree of shading they should be. And the whole secret is that the degree of shading is absolutely not related to the protection of the eyes from ultraviolet radiation, that is, it does not solve the main problem for which the purchase is made. You can choose the darkest glasses, but ultraviolet transmissive.
As a result, due to the decrease in illumination, the eyes will strain, the pupils will dilate and you will receive an increased dose of what you wanted to protect yourself from. Moreover, the blackest and lightest spectacle lenses can give the same result. What is the secret, then? Only special chemical additives are important, which are introduced into the composition of glass or plastic or applied to their surface.
Pay attention to the marking, it should indicate a very high percentage of UV retention. For example, if 100% of such rays are absorbed, the mark is 400 nm.
Some of the over-the-counter glasses are polished - this increases their quality and, consequently, the price. But how to check the quality in the optics department, in the store, on the street near the kiosk? To do this, you need to carefully look through them at some rectangular object. Take the glasses by the temples and, holding them in front of your eyes, close one eye. Move, slowly, glasses up and down and left and right. Follow the lines of the drawing, they should remain straight with any movement. Check again by closing the other eye. If everything is okay, the glasses will not spoil your eyesight. If the lines are crooked, especially in the center, try another one, otherwise vision problems are possible.

If you already have any vision problems, don't risk choosing sunglasses yourself. According to the recipe, they will make any, both from glass and from plastic. The former better protect against infrared radiation, which is less important, the latter - from ultraviolet radiation.
It is important to ask your ophthalmologist if you need glasses at all. In the middle lane, many do without them. Local residents of southern latitudes also most often do not use them - an adaptive reaction is triggered. And, in principle, locals of any latitude who do not intend to travel should be better served with goggles with a medium degree of shade. If the sun is not very worrisome, you can buy "chameleons" that darken in the light and brighten in the dark. True, there is one "but" here: darkening takes about a minute, and light recovery - 3-5 minutes. Perhaps such a restructuring will be annoying.
It makes no sense to wear glasses in transport, in cloudy weather, and especially in the evening. The eyes really need a stream of soft sunlight. And if you limit the light output all day and do not take off your glasses in the evening, you can harm your eyesight. When you block out sunlight with dark glasses during cloudy times, the pupils dilate and the outflow of intraocular fluid can be disrupted. And after 35-40 years, when women do not take off their glasses for a long time, fearing the appearance of wrinkles, there is a possibility of developing glaucoma.

Material
Here the choice is not great: plastic or glass. By and large, there is no difference. The second option is more suitable for people with poor eyesight and wearing ordinary glasses. They can wear "chameleons" in summer, or, as they say now, "photochrome" - glasses with lenses that are "tinted" in the sun. But "chameleons" are only glasses with glass lenses. Glasses with glass lenses plus and minus four or more have, as a rule, heavy glasses pressing on the bridge of the nose, where there are many nerve endings. (You risk becoming a patient of not only an ophthalmologist, but also a neuropathologist, suffering from headaches, irritability and insomnia). In addition, skin diseases on the bridge of the nose can develop under the arch of the glasses. So you have to choose: good visibility and protection from the sun with “chameleon” glasses or the tension of your “nasal” nerve endings with all the consequences.

Plastic always scratches faster, so you will likely need to change your glasses 2-3 times a year. Glass is more "scratch-resistant", but in any case glasses should be stored in a soft case and put the glasses only up.
Colour
If you have chosen plastic, then another question arises before you - the color of your accessory. As unfortunate as it may sound to some, not all glasses can be worn. Some colors will not help you look stylish and keep you “one” in the “vision” column of your medical record, while others will not. So what to wear and what not?
Red, orange, bright yellow glasses cause nervousness, increased excitability, sleep disturbance.
Dim yellow glass enhances contrast, suitable only for dim sunlight.
Blue glasses reduce the clarity of the image, negatively affect the retina.
Pink glasses will not only help you see the world in the best possible light, but will also greatly distort the light range. Suitable only for dim sunlight.
Black lenses are appropriate in bright light (beaches, mountain resorts). In other cases, with constant wear, intraocular pressure is increased.
The gray color is neutral and will not harm your eyes.
In neutrality, gray is echoed by brown, suitable for daily use.
And finally, if you want to get not only sun protection from wearing glasses, but also calm the nervous system, then green lenses are for you. You look and remember the "Wizard of the Emerald City" and your nerves will calm down possible memories of a carefree childhood.

Comfort
Pay special attention to details such as the movement of the nose pads - remember that rigid nose pads often press on the bridge of the nose and cause fatigue. In addition, nose pads can leave unsightly marks on the bridge of the nose. So it's best to choose frames with soft silicone, movable nose pads.
Earhooks
The size of the temples should strictly correspond to the distance from the frame to the bulge behind the auricle. The temples should not put pressure on the temples and the area behind the ear. The frame should be comfortable and not cause fatigue, even with prolonged use.
You should like the frame - if we talk about glasses not only as a device for correcting vision, but also as a means of a person's image and style, then the role of a correctly chosen frame is indisputable.
Decent frames for any face
In addition to functionality and convenience, which, undoubtedly, should come first when buying any glasses, even sunglasses, their appearance should also play an important role in the choice of worthy glasses.
And it's not just about the image. Glasses can change your appearance beyond recognition, both transform and disfigure. Remember, for example, the legendary Katya Pushkareva and her terrible glasses, which were the main focus of her not very attractive appearance.
Choose the shape of your glasses and frames carefully, taking into account the characteristics of your face.
Face shape
Experts suggest choosing glasses depending on the shape of your face. So, for example, it is believed that:

A rectangular face that is somewhat vertically elongated should choose glasses that cover most of the face and look like a wide transverse line. Such glasses will visually reduce the length of the face.
Frames with emphasized straight lines and rectangular glasses are suitable for round faces. A very dark rim color also reduces the fullness of the face.
For persons whose shape is closer to a square, that is, the jaw and forehead are wide, not very large frames with smooth curved lines are suitable, which will reduce the "squareness" of the face and add length to it. For such faces, frames with pronounced horizontal accents are suitable. Oval shapes with a bow on the bridge of the nose are also suitable. The high upper line compensates for the high elevation of the lower jaw line. Avoid lenses with bright, saturated colors.
Most frames will fit the classic oval face shape. The main thing is that they are proportional to facial features. The frame should be no narrower than the widest part of the face. Try to keep the top line of the frame close to the brow line and not create a second line.
You cannot wear fake glasses. Just in case, buy or order glasses in large pharmacies, company stores or in the optics department of your polyclinic. Cheap plastic glasses with no markings should alert you, they can increase the penetration of ultraviolet rays into your eyes, because you will constantly dilate your pupils due to lack of light. And one more important point: if you wear contact lenses, they will not protect you from the scorching rays. Wear lenses and glasses at the same time.