The legislation defines "personal protective equipment", but often 'to purchase one looks more' fashionable, pairing with a dress, the famous brand, color or frame, that 'in general to all that has little to do with the quality 'of the lenses. The legislation has instead defined with precision the characteristics that must have both the lenses that the frame of the sunglasses (1).
It 'hardly necessary to remember that sunglasses are used for eye protection from solar radiation, especially from ultraviolet rays and those purple-blue. In case of intense light eye shall gia 'to his defense with the narrowing of the eyelids, the restriction of the pupil, the shielding of the lens and the retina pigments, but if the exposure and' prolonged and 'prone to damage (conjunctivitis, cataracts, macular degeneration) that can be avoided with the use of sunglasses.
The lenses can be of glass or resin. The first will not scratch but 'can break and weigh more,' the latter are read but can get scratched.
The legislation classifies the lenses according to the filtering power, dividing them into four categories, depending on the degree of brightness' of the surrounding environment:
* Category 0-1: poor lighting;
* Category 2: average illumination;
* Category 3: full brightness';
* Category 4: strong lighting.
The glasses so they should be chosen according to the intensity 'of the light that surrounds us in sunny days to Category 3 and' the more 'fit. For guidance and 'not recommended to wear glasses Category 4 because it is very dark.
The mirrored sunglasses reflect the light more intense, reverberated altresi 'surfaces, white as snow. The reflection can 'result in burns to the nose.
The lens also can be:
* Photochromic (adjust the intensity 'of their own color to the amount' of light);
* Polarized (filter reflexes);
* Degrading (strong reduction of sunlight).
Depending on the quality 'optic lens you have the following qualifications:
* Optical class 1a;
* Optical class 2a.
The Optical class 1a and 'better.
The color of the lenses and 'quite varied. Recall that a simple clear lens stops ultraviolet radiation; the windows of the house have this function. The colors' are restful green, brown and gray. The color yellow and 'indicated when the sky is cloudy for skiers.
The frame can 'be in a biocompatible metal alloy or plastic to avoid ingestion of toxic substances.
Laboratory tests verify the ability 'of the lenses to absorb or reflect harmful radiation: the higher and' the percentage more 'high will be' protection. Other controls affect the quality 'and the shape of the glasses in their entirety.
The sunglasses must be accompanied by information note in which shall be entered:
* The manufacturer or his authorized representative;
* The degree of protection (from 0 to 4, from the more 'clear the more' dark);
* The type of sunscreen (photochromic, etc.).
* The optical class (1st or 2nd);
* The limits of use;
* The instructions for use;
* The CE marking (compliance 'European Union).
The Italian national unification (UNI) has prepared a general rule, the UNI 1836: "Personal eye protection - Sunglasses, filters for protection against solar radiation for general use and filters for direct observation of the sun ". The standard specifies the characteristics (mechanical, optical, etc), sunglasses and sunscreens that are not prescription lenses, but they have only the function of protecting eyes against solar radiation. The standard applies to lenses in common use (including those that are used on the road while driving), but does not cover the lens for protection from radiation from artificial light sources (eg sun) or the protective lenses of the goggles skiing.
(1) Decree legsl. n. 475/1992 and 10/1997. EU Directive 89/686 EEC.
What causes excessive exposure to the sun?
Excessive exposure to the ultraviolet rays of the sun, in the absence of adequate protection, it is very harmful in the eye as it is to the skin. It is estimated that only 14% of Italians adequately protect their eyes. One of the most common problems is related to exposure in places with a lot of reverb (beach or ski slopes), where you can be a victim of actinic keratoconjunctivitis, acute inflammation of the conjunctiva and cornea with symptoms such as pain, redness and sensation of having sand in occhi.L'eccessiva exposure to ultraviolet rays of the sun, in the absence of adequate protection, it is very harmful in the eye as it is to the skin. It is estimated that only 14% of Italians adequately protect their eyes. One of the most common problems is related to exposure in places with a lot of reverb (beach or ski slopes), where you can be a victim of actinic keratoconjunctivitis, acute inflammation of the conjunctiva and cornea with symptoms such as pain, redness and sensation of having sand in the eyes.