History of sunglasses contains not one hundred years. The Eskimo points - bone guards reckon with cuts which limit quantity of an incident light approximately as the most ancient. The first production lot of sunglasses was let out in France for Napoleon`s soldiers participating in the African war two hundred years ago. more than 50 years ago, during World War II sunglasses were a part of obligatory equipment of the American seamen, and for the first time used glass, cutting all ultra-violet range with wavelength 400 nanometers are shorter. According to household representation sunglasses have to be made of mineral glass and are subjectively comfortable. However long-term practice of use of sunglasses and modern the physician - biological researches showed that it is far not enough for full protection of eyes against damage by a sunlight and their presenilation.Light can call
that type of electromagnetic oscillations which causes visual feelings, light is the very wide range of radiations.development of some types of eye diseases Is known that light can have the damaging effect on optical environments of eyes, stimulate
. Surplus of an ultraviolet is most active and dangerous. It is dangerous also Xing - the violet part of a range since it passes freely a cornea and a crystalline lens (natural filters on UF) and its surplus leads to photochemical injury of a retina, i.e. directly photoreceptors. The researches conducted on macaques - a Rhesus factor showed that on chemical photoinjury of a retina Xing - violet part of a range by 800 - 900 times more active, than its red part. By the present moment it is established that sunglasses have to meet the following main requirements:
- to weaken visible light to comfortable feeling; in addition to weaken
- light of blue range (390 - 450 nanometers) dangerous to a retina of an eye and being reason of fotoretinit (a light burn of a retina) and a blindness from a senile makulyarny degeneration of a retina (irreversible injury of photoreceptors);
- in addition to weaken light in an ultra-violet strip of 320 - 390 nanometers accelerating development of a cataract;
- to block light of ultra-violet range 320 nanometers, causing burns of a cornea and conjunctivitis are shorter;
- to keep possible distinction of alarm flowers of the traffic light.
Spectral requirements to points are regulated by national standards. As the most rational it is considered to be standards of Great Britain - BS 2742, Germany - DIN 58217, the USA - ANSI Z80 and Australia - AS 1067. Standards of the USSR on sun-protection lenses and points do not meet 1975 - 79 the requirements of today. According to the specified standards there are 3 main groups of sunglasses - cosmetic (Cosmetic), usual (General) and points of high degree of protection (High UV - protection).
Cosmetic lenses, as appears from the name, are almost inefficient, but also are harmless. Lenses of high degree of protection are necessary first of all for highlands and a polar region, ekvatorialno - tropical regions and conditions of ozone anomalies. And, at last, lenses of General are the summer lenses meeting the requirements of our midland. In other words, at the choice of sunglasses for conditions of the raised solar radiation it is preferable to choose points with the increased ultra-violet protection and the lowered transmission in blue area of a visible range. By a visual assessment - on a gleam, colors of such lenses can be neutral, brown, zelenovato - brown, but not blue and not violet.
risk groups and situations when the sunlight can be especially dangerous to eyes Exist. Children, old men and people with retina diseases are most vulnerable to harmful effects of a sunlight. The most dangerous light conditions is excess solar radiation with the increased maintenance of ultraviolet and blue rays: highlands, polar region, southern seas and deserts. Therefore insistent advice to the inhabitants of a midland and more northern latitudes seeking to have a rest in the south - keep the sight on the future - protect the eyes qualitative sunglasses. Besides that in the south solar radiation is higher, from water more short-wave part of a range is in addition reflected, creating very severe conditions of work for eyes.
Physicians say that at people more than six solar burns which transferred during life, the risk of developing of a melanoma (cancer) increases twice, ultra-violet burns at early age are especially dangerous. And the most unprotected is our organ of vision, our eyes.
In ophthalmology are diseases which belong to so-called solntsezavisimy, it was already told about them, it is a cataract, turbidity of a cornea, fotoretinit etc. Insidiousness of radiation by excess solar radiation is in what at the time of radiation of people feels nothing. But over time it has an effect.by
conduct developments of “medical“ sun-protection and color lenses for simplification of visual perception of people with various eye diseases in recent years. In our country the leading medical organization for this problem are MNII of eye diseases of Helmholtz and the Russian Academy of Sciences.by
Choosing itself points, trust in the intuition (to you in them it has to be comfortable) and the provided standards. Do not save on the health - buy only qualitative goods.