Bifocal glasses: photo and description, types, principle of operation, benefit and harm, reviews
What are bifocal glasses? What are they good for? You will find answers to these and other questions in the article. Many people of retirement age throughout the day regularly change points. For example, one pair is used for watching TV, the other is used for reading, and the third is intended for the street.
This is explained by the fact that older people poorly distinguish between objects placed both far and near. This happens because presbyopia occurs - “senile vision”, or for some reason myopia progresses with the existing long-sightedness, and vice versa.
Specialists have developed correction lenses through which a person can equally clearly see both distant and close objects. This alternative in current ophthalmology is called bifocal glasses.Consider this universal version of optics in more detail below.
What it is?
Ophthalmologists usually prescribe bifocal glasses for hyperopia. This optics corrects vision - both close and distant. Write out such lenses for a variety of purposes: from reading to playing billiards. Points can be bought only after consulting a specialist and conducting a survey, with a prescription.
The basic advantages of such a device are a quick vision correction, an affordable price, and the possibility of choosing lenses for each patient with individual qualities.
Bifocal glasses are prescribed not only for adults, but also for children. Their disadvantages include the presence of contraindications, the occurrence of headache or nausea while wearing.
So what are the bifocal vision glasses? Each of the lenses of this device refracts light differently and contributes to the discrimination of objects at different distances. The top one helps to clearly see distant objects, and the bottom one - near ones.
These glasses are good because an individual can focus his gaze at any point of the lens and see the object. In the manufacture of the construction of the base focus on the lower zone.After all, it allows you to switch the view to different nearby objects and break the picture from them.
Thanks to this arrangement, you can see the smallest items and details. Such optics suits people of such specialties:
- text editors;
- representatives of different professions where it is necessary to work with tiny objects.
There are cases when a glass without diopters is inserted instead of the top lens. Such glasses are used only by people with myopia without external disorders of the visual organs. If you look at them, near objects will be perceived clearly, and distant objects - blurry.
The lower lens occupies any segment of glass, it can be of different shapes. If none of the suggested optics versions suits you, you can buy soft or hard bifocal lenses.
Selection of points
Agree on the photo bifocal glasses look great! Optics with double lenses should be selected based on the following parameters:
- vision parameters.
We have already said that such glasses can be bought only by a prescription made by an ophthalmologist.If you use optics in different situations, buy several types of glasses. For each patient they are selected in private.
Bifocal glasses are linear and progressive type. In the design of the first in the center there is a horizontal line. The second preserves a smooth focus transition. The following optical zones are possible with bifocal lenses:
- Concentric. They have optical rings.
- Variables. There is a line of delimitation of segments.
- Aspheric. The long distance zone is located at the edges, and the closest one is at the center.
At first it is quite difficult to get used to such optics. Over time, this feeling passes. In addition to bifocal glasses, there are trifocal (with three or more lenses) and multifocal.
Benefit and harm
Consider the benefits and harm of bifocal glasses. The advantages of this optics include the following properties:
- low cost and availability for different patients;
- no need to use multiple pairs of glasses;
- the ability to customize lenses to the needs and requirements of each person.
Among the shortcomings, experts point out:
- long period of adaptation;
- the presence of blind spots;
- too long inclusion of the central segment of the view (the need for drivers);
- the possible occurrence of nausea, migraine, pain in the eye area;
- uninterrupted switching of the eye from one diopter to another, causing discomfort and fatigue.
The optics considered by us has contraindications. It is not prescribed for:
- anisometropia - anomalies, in which the sharpness of vision of the right and left eyes is not the same (the difference is more than 2 diopters);
- personal intolerance to corrective glasses;
- nystagmus - involuntary vibration of the pupils.
Before acquiring glasses, it is necessary to be examined and consult with an ophthalmologist (we spoke about this above).
Unlike single-focal classical lenses, bifocal lenses for glasses have two optical segments separated from each other, the difference between which is approximately 2-3 diopters (but the presented value cannot be exceeded).
One of these segments is designed to work with tiny details, text, and the other for viewing distant objects.These segments can be both the same size (half-glasses), and different. In some cases it is allowed to make glasses with small inserts for working with the smallest objects or text. Each of these segments has its own optical center.
How does a person work in such glasses? It is enough for him to translate the view from one zone to another. For example, if you need to perform any small work or read the text, a person looks at small details through the lower segment. If he wishes to consider any object placed in the distance, he looks to the upper sector of the device.
And in fact, and in another case, the individual can achieve a uniform perfect picture. Today these types of glasses are very widespread. They are recommended to physicians, drivers, teachers, as well as short-sighted people who just want to lead an active lifestyle, without using several pairs of glasses daily. For each of these categories of consumers a unique, most successful type of lens with two optical segments is selected.
All of the above types of lenses, in addition, are divided into ultra-thin and standard, blacked out and simple, as well as photochromic (chameleons).Some types of lenses are additionally equipped with different filters, thanks to which they protect the eyes from ultraviolet radiation or any other harmful external factors.
How much are ready bifocal glasses? Their price depends on all the above parameters, as well as on the raw materials from which they were produced, and the brand that creates the presented devices. In different salons of optics, the cost of glasses is not the same, but it usually ranges from a couple of hundred to several thousand rubles.
So, budget options in Russia cost from 500 to 1000 rubles. The price of expensive points, made individually for an order, can reach 10 thousand rubles.
The range of variations of such optics is huge. It not only allows you to see the world in rich colors, but can also be an addition to the style.
What reviews of bifocal glasses are left by people? Many argue that these devices are the best option for reorienting gaze from others to distant objects. Some do not like a number of shortcomings that they have, but they say that they can be fixed with more expensive and sophisticated models.
Often people complain about the discomfort that appears at the beginning of wearing bifocal glasses.They have to acquire an important habit of translating the gaze from one working segment of the device to another.
Some argue that the discomfort disappears in the first weeks of wearing optics. Others write that they had to re-apply to the doctor with ready-made glasses in order to make sure that they were made correctly. In any case, the optics we are examining helps people to see the world around better. Use innovative glasses and be healthy!