A suitable model of sunglasses should protect the eyes not only from blinding light, but also from the negative influence of ultraviolet rays. These two main indicators help determine the quality and scope of a particular model of such glasses. To choose the most suitable option, you need to know the basic degrees of protection of such products.
The effect of solar radiation (ultraviolet) on the eyes
Prolonged exposure to the sun without special safety glasses can provoke adverse effects on vision. The maximum precautionary measures in sunny weather should be taken by those who have poor health or various ophthalmological diseases.
The most unsafe period for eyes that are not protected by special glasses is considered to be early morning and the afternoon. If the sun is low, its detrimental effect on the eyes increases several times.
When such rays are reflected from a large surface of water bodies, the level of negative influence of ultraviolet radiation increases. In the process of selecting such products by type of protection, it is advisable to take into account exactly what effect this type of rays have on unprotected or weakly protected organs of vision.
The effects of prolonged sun exposure on the eyes
The most common consequences of prolonged exposure to the organs of vision of UV rays include the following:
- a feeling of dryness and burning, redness of the eyes;
- photophobia (photophobia) - painful sensitivity of the organs of vision to light, accompanied by spasms of the eyelids and lacrimation;
- photokeratitis - a burn of the cornea and conjunctiva, which is accompanied by edema, inflammation and significant pain;
- conjunctivitis - manifests itself in the form of aseptic inflammation;
- ptegyrium (pterygoid film - thickening of the conjunctiva crawling on the cornea);
- cataract and clouding of the lens (discoloration, decreased visual acuity).
Important! The consequences of the negative effects of UV rays do not appear immediately. Directly during irradiation, pain may not be present, however, ignoring protective equipment during this period is not recommended.
How to choose sunglasses by type of protection?
When selecting safety glasses, a number of certain parameters are taken into account, which include: the level of the ultraviolet filter, the material of manufacture and the color of the lenses. These parameters (light transmission categories) have a direct impact on the safety of use and the effectiveness of wearing such accessories.
Degrees of protection of sunglasses from ultraviolet
Ophthalmologists distinguish several degrees of protective qualities of such products:
- The minimum. The degree of protection is 10-15% . It is better to use similar models in cloudy weather.
- Initial. Provides penetration from 40 to 75% of sunlight. Such glasses are recommended to be worn in the morning and in the evening under the gentle sun.
- Medium. Able to retain up to 65% of sunlight . These models are recommended for hot sunny weather.
- The maximum. Passes only 7-10% of ultraviolet radiation . It is used for maximum protection of the organs of vision. Suitable for those who suffer from photophobia. Also suitable for lovers of surfing and skiing.
Labeling value UVA or UVB radiation
In terms of intensity, UV rays are divided into:
- UVA radiation, which makes up about 90% of all UV radiation reaching the Earth’s surface and has a maximum penetration effect (long waves, the length of which can correspond to 320-400 nm).
- UVB radiation (medium waves, the length of which can be 280-320 nm). Rays representing the greatest danger to the eyes, damaging the tissues of the organs of vision and causing sunstroke.
High-quality products always bear the manufacturer's mark corresponding to the ultraviolet bandwidth and the spectrum of the rays.
Another popular marking
To choose the most suitable model for such glasses will help a different kind of marking, often used by manufacturers. Thanks to this marking, you can find out about the bandwidth of ultraviolet rays:
- High UV-protection - products with very darkened lenses, providing the highest degree of protection against UV rays. A great option for relaxing in hot sea resorts or in the mountains.
- The degree of transmission of UVA rays from 85 to 98%. It is recommended for use with not very scorching sun.
- Blocks up to 70% of the dangerous rays of both varieties ( UVA and UVB ). A good choice for urban environments.
- Cosmetic - sunglasses that block less than 50% of ultraviolet radiation. Models of this type are better not to use with the active sun, since they will not be able to provide the organs of vision one hundred percent protection from such rays.
- General - a universal option with UV filters, blocking from 50 to 80% of UV rays. Such models are suitable for everyday eye protection in a city at mid-latitudes.
Yellow models block bright blue light well and are considered an excellent option for use in cloudy weather and in the evening.
Mirrored glasses perfectly reflect visible sunlight and are designed to be worn during periods of increased solar activity, in hot countries and in the mountains.
The lenses of chameleon glasses change the degree of dimming depending on the lighting and are suitable for use in urban environments. Such photochromic lenses are an indispensable option for professional athletes, tourists and motorists. In particular, such models are convenient for those who wear glasses with diopters, as they darken in the sun and remain transparent in the room.
Polarized models block aggressive bright light well and are ideal for use in the mountains, on the beach, behind the wheel of a bicycle, motorcycle or car.
Graduated models slightly change color reproduction and are suitable for use in urban conditions during a period of low solar activity.
Glasses with gray or malachite lenses are distinguished by a clear image transmission without visible distortion. This is a universal option that can be successfully applied both on the sea beach and in urban environments.
What is indicated on the bow, glass or label?
On these parts of glasses of this type, you can find information on :
- manufacturing material (glass - lenses made of glass, plastic - lenses made of plastic);
- degree of protection against ultraviolet rays (for example, 100% UV);
- manufacturer (brand name, model, country and barcode);
- quality standard (ANSI Z80.3 - American, EN 1836 - European, AS 1067 - Australian).
Important! Do not use glasses that have the highest degree of protection when driving. Strong dimming can adversely affect visibility.
Does glass or plastic protect against ultraviolet radiation?
Buyers often wonder which option is best to choose: with glass or with plastic lenses? If we consider the functional characteristics of such products, then both those and other models of good quality have the same optical functions and the same level of protection against harmful effects. You can notice the difference in the visual perception of the image through various types of lenses.
Pluses of plastic
Products from this material have the following advantages :
- lightness (almost not felt during use);
- safety (do not break when struck by fragments);
- wide selection of frames;
- diverse tinted lens palette.
The following positive qualities are inherent in such lenses :
- immunity to temperature fluctuations;
- protection against minor damage (scratches, etc.);
- attractive appearance due to thinner lenses.
Features of polarized glasses
The main useful property for which such glasses are used is the protection of the eyes from the blinding glare that appears due to the reflection of the sun's rays from many surfaces. These glare can occur when light hits the roadway, the surface of water bodies, snow lying on the ground, roofs and walls of various buildings.
Reference! The unique qualities of polarizing glasses are manifested thanks to a special filter, similar to a thin liquid crystal film placed between layers of glass or plastic.
How to distinguish fake glasses?
It is recommended to choose such products very carefully so as not to buy a fake version. Using products of inadequate quality can lead to very undesirable consequences.
Distinctive features of low-quality glasses :
- small lenses;
- low degree of protection;
- too heavy a frame;
- imitation of popular brands;
- lenses in blue, orange and red ;
- very close or too large.
Advice! Visually impaired people are advised to visit an ophthalmologist before purchasing this kind of product. A specialist will help you choose the right goggles with diopters.
Fakes: in the center and on the right.
People are exposed to ultraviolet radiation, it can cause significant damage to vision. Sunglasses are a truly indispensable accessory for every person. Depends on how correctly selected glasses of this type, they will protect the eyes from the harmful effects of ultraviolet rays or, conversely, harm them.