We have already talked to you about the dangers of ultraviolet (UV) radiation, such as mountain activities or activities during the summer holidays. But here we want to talk more about UV rays, what they are, how they act and what dangers to the eye.
According to the World Health Organization (WHO) UV radiation is an electromagnetic radiation with wavelengths between 100 and 400nm. In small amounts, UV rays are beneficial to health and play an essential role in the production of vitamin D. However, excessive exposure to them is related to different types of skin cancer, sunburn, accelerated aging of the skin , Cataracts and other eye diseases. It has also been shown that these radiations lessen the effectiveness of the immune system.
Also an analysis of the burden of morbidity has been carried out to evaluate the role of solar UV radiation as a risk factor for human disease. And although the estimates are complicated to remove it has been seen that the greater burden of morbidity caused by UV radiation is due to cortical cataracts, malignant cutaneous melanomas and sunburn
MORBIDITY: Number of people who become sick at a given place and time in relation to the total population.
WHAT TYPES ARE THERE AND WHAT PERCENTAGE OF UV WE HAVE?
There are three main types of UV rays:
• UVA rays age the skin cells and can damage the DNA of these cells. These rays are associated with long-term damage to the skin.
• UVB rays have a little more energy than UVA rays. These rays can directly damage the DNA of skin cells, and are the main rays that cause sunburn. It is also believed to cause the majority of skin cancers. These rays are partially absorbed by the ozone layer.
• UVC rays have more energy than other types of UV rays, but they do not penetrate our atmosphere and are not in sunlight. They are very harmful but are not normally a cause of skin cancer.
The power of the UV rays that reaches the ground depends on a number of factors, such as:
• Time of day: UV rays are more powerful between 10 a.m. and 4 p.m.
• Season of the year: UV rays are more powerful during the spring and summer months. This is a less important factor near the equator.
• Distance from the equator (latitude): UV exposure decreases as it moves away from the equator
• Altitude: More UV reaches the ground at higher elevations.
• Cloud formation: The effect of clouds can vary, as cloud formation sometimes blocks some UV rays from the sun and reduces exposure to UV rays, while some types of clouds can reflect UV rays and may increase exposure To UV rays. What is important to know is that UV rays can penetrate clouds, even on a cloudy day.
• Reflecting surfaces: UV rays can bounce off surfaces such as water, sand, snow, pavement, or grass, leading to increased exposure to UV rays.
WHAT DOES EYE DAMAGE IMPLY?
The general population understands very well the consequences of skin exposure to UV radiation, but this level of understanding is very different when we talk about the eye. Only 7% of people associate UV with eye problems.
The eye has structures that help absorb and protect us from UV rays. The cornea is able to absorb most of the UV-B radiation and the UV-A crystalloin.
Because we should not forget that injuries generally come as a result of an accumulation of exposure to the sun. But short periods of very intense sun exposure with a very high UV index can cause damage in the same way. It is estimated that exposure to UV radiation of only 2 hours is sufficient to cause solar keratitis. It is also known as snow blindness and is an inflammation of the cornea induced by acute exposure to UV radiation.
ALTHOUGH IT IS IMPORTANT TO KNOW THAT small doses of UV radiation are beneficial to humans and essential for the production of vitamin D. UV radiation is also used to treat various diseases such as rickets, psoriasis and eczema. These treatments are performed under medical supervision and the weighing of their advantages against the risks of exposure to UV radiation is a matter of clinical judgment.
THE UV INDEX
According to the Spanish Meteorological Agency (AEMET) the ultraviolet index (UVI or Ultra Violet Index) is a measure of the intensity of ultraviolet radiation reaching the surface of the Earth. There is currently a standard UV Index of the World Health Organization in collaboration with the World Meteorological Organization, the United Nations Environment Program and the International Commission for Non-Ionizing Radiation Protection. It not only standardizes the calculation methods of the index but also a color code and graphics to offer the information to the public.
In many countries the IUV is reported in the weather forecast for newspapers, television and radio; However, usually only this information is given in the summer months.
In the following table you can see the precautions to be taken depending on the UVI indicated for that day.
WHAT SIMPLE MEASURES CAN BE TAKEN TO PROTECT THE SUN?
Shade, sunglasses, clothing and hats are the best protection. In addition, it is necessary to apply a cream with sunscreen on the parts of the body that are exposed.
Below we will describe the different damages that can cause in the different eye structures.
• In the cornea: UVB can cause keratitis, as is often the case for skiers in the snow. This corneal lesion causes photophobia and a gritty sensation inside the eyes.
• In the conjunctiva: UVA and UVB can cause pterygium or pinguinus.
• In the lens: Although most people have a greater or lesser degree of cataracts as they age, sun exposure, particularly exposure to UVB radiation, appears to be one of the major risk factors for cataracts. Cataract is currently the leading cause of blindness in the world
• In the retina: the radiation from the sun can “burn” the foveal retina, for example, if we see a solar eclipse without adequate protection.
In addition, there is a relationship between solar radiation and age-related macular degeneration (AMD).
• In the eyelids: the sun can cause skin lesions that can develop cancer of the skin of the eyelids.
Avoid sun exposure in the central hours of the day.
Note the UV index. This important information helps you plan your outdoor activities to avoid excessive exposure to the sun’s rays.
Take advantage of shadows. Put yourself in the shade when the UV rays are more intense, but do not forget that trees, umbrellas or awnings do not fully protect against solar radiation.
Wear protective clothing. A wide-brimmed hat protects the eyes, ears, face and back of the neck properly. Sunglasses with a protection rating of 99% -100% against UVA and UVB rays considerably reduce eye damage due to solar radiation.
Avoid lamps and tanning beds. Lamps and tanning beds increase the risk of skin cancer and can damage the eyes if protection is not used. Its use should be completely avoided.
VERY IMPORTANT
Special emphasis should be placed on directing recommendations for children and young people as frequent exposure to UV radiation and sunburn suffered during childhood and adolescence are a major risk factor for skin cancer
Protect children. Children are often more vulnerable to environmental hazards than adults. When outdoors, protect them from exposure to UV rays as explained above. Babies should always remain in the shade.
If you wear sunglasses, make sure your child uses them as well.
AND FOR THE EYES WHAT SUNGLASSES?
A common mistake is to believe that all dark glasses protect against UV radiation. The truth is that, IF SUNGLASSES HAVE SPECIAL FILTERS TO HOLD THIS TYPE OF RADIATION, THE DAMAGES in our visual health will not only be the same, but they will INCREASE.
This happens because the lenses will only filter the light intensity, that is to say gives us the sensation of having less light, causing a greater dilation of the pupil and a greater entrance of UV radiation in the eye. With bad sunglasses we not only do not protect ourselves, but we also CANCEL OUR NATURAL PROTECTION SYSTEMS.
If you want to know more about sunglasses for mountain activities, read this interesting article “Your vision at the top”
A SAD NEWS
29.6% of this type of articles are acquired in blanket tops and markets. This channel, without any regulation, sells more than 6 million units. Almost 4 million units are used for promotions of companies and products and as gadgets for offers like newspapers or magazines. Another 2 million units are distributed in bazaars, small businesses such as “everything for 1 €” and gas stations.
This means that almost 60% of the sunglasses purchased in Spain are distributed in channels with very low quality guarantee.
Analysis carried out by the Complutense University of Madrid on filters (glasses) of a sample of glasses marketed in bazaars, top blankets and non-sanitary establishments in Spain have shown a dramatic result, since 93% of the analyzed glasses have lenses that Do not comply with current regulations with the consequent risk to visual and ocular health.
Optician-optometrists recommend advising and purchasing sunglasses in sanitary facilities of optics that guarantee compliance with the safety and quality regulations and the selection of the appropriate sunscreen for each user and every need.
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