"N-nada glasses?" Or "what are the disadvantages of ready-made Chinese glasses with diopters"?

Many people (especially older ones, especially given the impatience of Russians) are tempted to buy ready-made eye glasses (usually from China) in transition or mini-optics in a supermarket. Than it can threaten I asked to tell Habr's readers an expert in medical optics Irina Shevich.

Glasses are medical products, but you cannot say about ready-made glasses that they are as accurate as "at the pharmacy".

This is the "extras", with all the ensuing consequences.

All parameters in Chinese glasses are "floating". You think you are buying +3.0, and there may be more or less - how lucky. Or not lucky
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A saleswoman in a kiosk explains to customers: “These are“ universal ”glasses, with“ floating centers ”62-66.” If, however, check the points on the diopter, you can see that the centers "swim" to 70 - 72 mm.


Optics - not a clothing store, and glasses, with averaged data, this is not a shirt, of any size, which can be tightened with a belt.

In the finished glasses, by the way, not only in Chinese, it does not take into account that one person may have one eye closer, the other farther from the center of the nose bridge. One above, another below. Symmetrical persons in nature almost never occurs. The total distance of 64 mm is composed, for example, of monocular 31/33 or 33.5 / 30.5.


As a result of improper alignment of the lenses, the visual axis of the eye does not coincide with the optical axis of the lens, and then the person falls into the zone of aberrations (distortions). They are the greater, the higher the optical power of the glasses, and the farther from the center of the lens.

People with incorrectly assembled glasses are lowered, raised or tilted their head in order to “locate” the optical center of the lens.

The eye makes an “adjusting” movement, an unnatural motor tension arises, which can develop into heterophoria (latent squint). A person is saved only by the rejection of the constant wearing of such glasses, and hidden strabismus will arise from him for another reason - often because he does not use correction at all.

The task of the glasses is to move the focus of the image to the retina, but the finished glasses do not correct astigmatism. The image "poddvivaet", because instead of a point, an astigmatic eye builds two foci, two lines. Houses, trees, dimensions of the machine instead of clear contours, have shadows and blurred outlines. The internal muscle of the eye, which is responsible for a clear vision, is overstrained, making microfluctuations. This can cause metabolic disorders in the muscle fibers and contribute to the development of pathology of the retina and other eye diseases.

As for the material of the lenses in the finished glasses, as a rule, this is the simplest and rather fragile optical plastic, with a cheap coating, and even without it. As a result, the glasses let out the ultraviolet that is harmful to the eyes, and additional parasitic highlights and scratches form on the lens surface.

Some videos on the topic

Have you seen loops in the Pyaterochka stores? If the glasses are broken, or forgotten at home, a magnifying glass will provide an opportunity to read the labels on the goods. Ready-made glasses are a similar tool of temporary use for a period while a person is waiting for getting custom-made glasses specifically for him.

I thank for the preparation of the material Irina Shevich, director of the Institute for Advanced Studies and Professional Retraining "Opti-class" .

If you have an interest in this topic (for those who have not yet made laser Relex SMILE vision correction and have not gotten rid of the glasses), write in the comments - what questions regarding eye correction do you care about, and we will try to prepare relevant posts.