See the invisible. Why people can't see ultraviolet light and how language changes the perception of colors

What is light?

In order to understand what blue light is, let's first understand the basic term - light.

Everyone has seen how a beam of light breaks into a dark room; if to the naked eye the light looks like a homogeneous static structure, then this is far from the case.

Light is electromagnetic radiation that has a wave nature; in other words, light propagates in the form of periodic oscillations or, in other words, waves; these waves, like waves on the sea, have an amplitude, that is, the frequency with which they oscillate.

The structure of light consists of photons. Photons are such tiny bundles of energy, but a Photon is not a simple particle, it is a small segment of an electromagnetic wave.

Don't worry, we won't go deep into quantum physics here. All we need to know is that light travels in waves, they differ from each other in energy and length. The longer the wave, the less its energy.

The wavelength of light is measured in nanometers (nm) - that is, one nanometer is equal to 10-9 meters, these are very, very small distances, by the way, we mean the most common familiar meter, if you want a tailor.

Light waves have different lengths and the human eye is capable of perceiving only waves of a certain length; this range is usually called the visible spectrum or visible radiation. It is believed that the eye can perceive electromagnetic radiation with a length from 380 to 760 nm.

The figure below schematically represents a light wave with a division into the visible and invisible spectrum of the light wave.

The longer the wave of light, the more infrared radiation it contains; the shorter the wave becomes, the more ultraviolet radiation increases.

Smaller wavelengths are called ultraviolet. To the right of the visible range begins the region of infrared radiation. But if we take the entire electromagnetic spectrum of waves, that is, the entire limit within which electromagnetic waves can oscillate, then we will see that their visible radiation, namely what we call light, is a rather small gap.

And as we see, a deviation to the left gives us UV radiation, X-rays, gamma radiation, which is certainly very harmful to our eyes, but this does not mean that infrared or microwave radiation is good for the eyes, it is also harmful and dangerous for the organs vision, for example, on any devices using an infrared laser there is a danger warning, here are some examples of such messages:

What is the effect of ultraviolet radiation on the human body?

Prolonged and intense exposure to UV radiation can be harmful to living organisms - animals, plants and humans. Note that some insects see in the UV-A range, and they are an integral part of the ecological system and in some way benefit humans. The most famous result of the influence of ultraviolet radiation on the human body is tanning, which is still a symbol of beauty and a healthy lifestyle. However, prolonged and intense exposure to UV radiation can lead to the development of skin cancer. It is important to remember that clouds do not block ultraviolet light, so a lack of bright sunlight does not mean that UV protection is not needed. The most harmful component of this radiation is absorbed by the ozone layer of the atmosphere. The fact that the thickness of the latter has decreased means that UV protection will become even more important in the future. Scientists estimate that a decrease in the amount of ozone in the Earth's atmosphere by just 1% will lead to an increase in skin cancer by 2–3%.

Why is ultraviolet radiation dangerous?

So, we found out that if we start from the table, then red light is the right zone of the visible spectrum and further to the right, and blue light is what is on the left side of the diagram, that is, this is the leftmost edge and further, all this relates to blue light, otherwise called ultraviolet radiation.

Let's figure out what the danger of blue light and ultraviolet radiation is.

The numbers may vary slightly in different standards and sources; for example, the well-known ISO standard for solar radiation divides UV radiation into the following groups:

It is believed that humans in the natural environment usually have contact with UV radiation ranging from 200 to 400 nm.

What is UV radiation

Solar ultraviolet radiation is electromagnetic rays that occupy the spectral range between visible and x-ray radiation. UV wavelengths range from 10 to 400 nanometers. UV rays are divided into 3 types based on wavelength - they affect human vision in different ways.

• Ultraviolet C (UVC) is an ultra-short and most dangerous ray, the spectrum of which is close to X-ray radiation. It is believed that UVC rays are completely absorbed by the atmosphere and do not reach the earth's surface. However, due to ozone holes, some of the ultrashort rays still reach the Earth.
• Ultraviolet B (UVB) is short-wave radiation that accounts for 0.5% of the solar spectrum. UVB rays promote the production of vitamin D. They also give an immediate phototoxic effect in the form of skin redness and burns. The cornea of ​​the eye almost completely absorbs this type of radiation, which destroys its cells.
• Ultraviolet A (UVA) is the so-called “black light” that reaches the surface of the earth. It penetrates human skin and causes cell aging. Radiation of this type often causes skin cancer. The cornea and lens retain UVA and are exposed to their aggressive effects

.

The main rule of ultraviolet radiation

The shorter the wavelength, the more dangerous the ultraviolet radiation.

Because everything below 200 is “filtered” by the planet’s ozone layer and, as a rule, does not reach its surface.

UV radiation from 200 to 315 nm is partially filtered by the ozone layer, but still a small part of it reaches the surface of the planet, and it is precisely due to this type of radiation that we tan our skin in the summer, but this type of rays is harmful to the eyes because the exposure is too intense This type of UV rays causes photokeratitis

, which can lead to temporary loss of vision (severe photokeratitis is often called “snow blindness”), as well as other complications associated with disruption of the normal condition of the cornea and eyelid.

The risk of photokeratitis increases at high altitudes, as well as in snow, if the eyes are not protected from ultraviolet radiation. Note that the effect of ultraviolet radiation in the UV-B range is limited to the surface of the eye; these ultraviolet rays practically do not penetrate into the eye.

UV radiation in the range from 315 to 390 nm, being close to the visible spectrum, is in itself less dangerous. However, these rays are able to penetrate deep into the eye and have a damaging effect on the lens and retina.

Exposure of the eyes to UV radiation in this range for a long time leads to an increased risk of a number of dangerous eye diseases, including cataracts and macular degeneration, which is considered the main cause of blindness in old age.

In recent years, experts have paid much attention to blue rays of the visible spectrum (about 400 nm), which are directly adjacent to the long-wave part of the UV range, believing that prolonged exposure to these rays of the visible spectrum on the eyes is also unsafe, since they penetrate deeply into the eye and affect retina With short-term, strong exposure to UV radiation (if you look at welding, a bactericidal lamp, watch a solar eclipse without protective filters, or do not protect your eyes at high altitudes), eye damage called photokeratitis is possible.

Photokeratitis:

This is a burn that damages the cornea of ​​the eye (the cornea is the clear and slightly convex part of the eye).
But don’t think that if you avoid strong UV radiation, you are safe; the fact is that the effect of ultraviolet exposure is cumulative, that is, it accumulates in the body. Ultraviolet radiation is ionizing and produces free radicals that damage “normal” molecules, including DNA, RNA and protein molecules. Damage to cells and tissues accumulates with age, leading to deterioration of vision, the development of cataracts and retinal damage.

Important point

Until a person reaches middle age, blue light is not absorbed by natural physiological filters such as the tear film, cornea, lens and vitreous body of the eye. The highest permeability of short-wavelength visible blue light is found at a young age and slowly shifts to the longer wavelength visible range as a person lives longer. The eyes of a 10-year-old child can absorb 10 times more blue light than the eyes of a 95-year-old person.

Artificial sources of UV radiation are harmful not only to the eyes

For several decades, scientists have carefully studied the effect of blue light on the human body and have found that its prolonged exposure affects not only eye health, but also circadian rhythms, and also provokes a number of serious diseases.

Many studies in recent years have found a connection between working night shifts when exposed to artificial light and the occurrence or exacerbation of cardiovascular diseases, diabetes, obesity, and prostate and breast cancer in subjects. Scientists associate their occurrence with the suppression of melatonin secretion by blue light, which affects human circadian rhythms.

Circadian rhythms (from Latin circa - around, around and Latin dies - day) are cyclical fluctuations in the intensity of various biological processes associated with the change of day and night, or the so-called internal clock of the body.

Over the course of long evolution, man, like all living things on Earth, has adapted to the daily change of dark and light time of day.

One of the most effective external signals that support the 24-hour human life cycle is light. Our visual receptors send a signal that goes to the pineal gland; it determines the synthesis and release into the bloodstream of the neurohormone melatonin, which induces sleep. When it gets dark, melatonin production increases, and a person wants to sleep. Bright lighting inhibits the synthesis of melatonin, and the desire to fall asleep disappears. Melatonin production is most strongly suppressed by radiation with a wavelength of 450–480 nm, i.e. blue light.

From an evolutionary point of view, the time humanity has used electric lighting is negligible, and our body in today's conditions reacts in the same way as our distant ancestors.

This means that blue light is vital for the proper functioning of the body, but the widespread introduction and prolonged use of artificial lighting sources with a high spectral content of blue light, as well as the use of a variety of electronic devices, not only harms our eyes, but also disrupts our internal clock . Research shows that spending 30 minutes in a room illuminated by a cool blue fluorescent lamp is enough to disrupt melatonin production in healthy adults. As a result, their alertness increases and attention weakens, while exposure to lamps emitting yellow light has little effect on melatonin synthesis.

Eye pathologies developing under the influence of UV rays

Ultraviolet radiation provokes the development of serious diseases.

Photokeratitis

Inflammation of the cornea and conjunctiva of the eye due to sunburn. The development of photokeratitis can be caused by exposure to bright light reflected from snow, sand or water. The disease is accompanied by pain, photosensitivity and redness of the eye mucosa.

Pterygium

Benign growth of conjunctival tissue onto the cornea. This pathology is called "surfer's disease" because it most often occurs in people who spend a lot of time outdoors in the bright sun. Symptoms of pterygium are redness and inflammation of the mucous membrane of the eyes, a sensation of a foreign body under the eyelid.

Read more on our blog - “Pterygium”.

Cataract

Partial or complete clouding of the lens, which can lead to deterioration and even loss of vision. Cataracts develop due to the aging of the body, but frequent exposure to ultraviolet radiation can accelerate this pathological process. With cataracts, vision becomes blurred and blurred, the person becomes sensitive to bright light and loses the ability to see at dusk.

Read our article “Glasses and lenses after cataract removal.”

Age-related macular degeneration

Damage to the central zone of the retina of the eyes, developing as a consequence of age-related changes in the body. Frequent exposure to ultraviolet radiation accelerates the process of tissue destruction and often leads to blindness. Main symptoms: decreased visual acuity, deterioration of color perception, distortion of the contours of objects.

Exposure to ultraviolet radiation can cause the appearance or development of certain eye diseases. The longer the eyes are exposed to this effect, the higher the risk of serious vision pathologies.

About age-related macular degeneration in our blog.

What are the types of blue light sources?

All sources of ultraviolet radiation can be divided into natural and artificial. The main source of UV radiation in nature is the sun; in short, the sunnier the area, the more UV radiation your body, as well as your organs of vision, will receive. With artificial UV sources, the situation is more interesting, since we have many more such sources in everyday life.

Lighting lamps

Not all lamps produce UV radiation, for example, an ordinary incandescent lighting lamp, which is popularly called an Ilyich light bulb, which produces light by heating a tungsten filament, is a source of infrared radiation, since in its radiation spectrum the infrared region occupies almost 75%.

Types of lighting lamps that are a source of UV radiation:

• LED bulbs;
• mercury lamps;
• luminescent;
• bactericidal lamps;
• photosynthetic.

It must be said that all the lamps from this list are sources of artificial UV radiation, regardless of what type of design the lamp itself is made of, in the form of a compact light bulb or a large long structure, the type of lamp itself is important.

There is no doubt that all these artificial sources of UV radiation are harmful to the organs of vision, so try to avoid long-term exposure to them and try to limit their use in domestic conditions.

Sources of UV radiation in household appliances:

• monitors;
• smartphones;
• laptops;
• mobile game consoles;
• TVs;
• 3D helmets and 3D glasses;
• Digital cameras and cameras.

It is important to understand that this is not a complete list, since new devices are constantly being released that use screens in their design, the image on which is formed by illumination with fluorescent lamps or LEDs, also called LED backlighting; all of these devices are a source of harmful UV radiation.

When is ultraviolet radiation especially dangerous?

Ophthalmologists recommend protecting your eyes from ultraviolet radiation not only in sunny weather: a significant portion of UVA and UVB rays reach the surface of the earth even on cloudy days.

Not only direct sunlight, from which we are accustomed to hiding, damages the eyes, but also scattered ultraviolet radiation - radiation reflected from the surface of reservoirs, snow, sand and asphalt.

The damaging effects of UV rays on the eyes depend on the following factors:

• Geographic latitude of the location. The most dangerous zone is the equatorial one.
• Height above sea level. The higher, the more damage to the eyes.
• Times of Day. From 10 am to 4 pm the sun's rays are especially aggressive.
• The proximity of bodies of water and large amounts of snow, which reflect UV radiation.

There are medications that increase the negative effects of ultraviolet radiation on the eyes. These are, for example, tetracycline and some diuretics. If you are taking any medications, check with your doctor to see if they may have this effect.

Is there blue light protection?

An interesting feature, almost every woman and girl knows that being in direct sunlight is quite dangerous, and as a rule, on the beach they apply various creams and products to themselves and their children that prevent or greatly weaken the amount of ultraviolet radiation reaching the skin, since as a result of this Intense UV radiation can cause quite serious complications, including skin cancer. But for some reason, few people think about the fact that not only our skin needs protection from UV, but also such a delicate organ as the eyes, which, as we found out in this material, are also highly susceptible to the negative effects of UV rays.

Fortunately, ophthalmology does not stand still at present and has made a major breakthrough in the field of vision protection from ultraviolet radiation. Nowadays, lenses and glasses have been developed that will help completely protect the eyes of you and your children from negative ultraviolet radiation of both natural and artificial origin. A number of spectacle lenses with optical coatings are already available on the market in our country, which help reduce the effect of blue light on the eyes.

If there is not much sunshine in our region and our grandparents very often retained good eyesight into old age, in our time it is impossible to be aloof from the huge number of gadgets that surround our lives more and more every year, and this in its turn has the most negative impact on eye health, so take care of your eye health in advance, because as you know, it is easier to prevent a disease than to treat it.

You can protect yourself from dangerous ultraviolet radiation quite easily by simply using glasses or contact lenses, but unfortunately, not all glasses and lenses can protect your eyes from UV radiation. Only lenses with a special coating have guaranteed UV protection.

The Crizal company, of which our clinic is an official partner, conducted many years of research and testing, which resulted in the invention of a special coating, Crizal Prevencia, which protects the eyes from dangerous blue-violet light that causes the death of retinal cells, and at the same time it transmits the blue-blue light necessary for the general well-being of a person and the regulation of his biological clock. As well as Crizal Eyezen, these lenses are designed to optimize the perception of information from digital screens of gadgets; they use 3 revolutionary technologies:

• Power Distribution Technology - Increased power at the bottom of the lens is designed to support the demanding accommodation and convergence mechanisms of our eyes;
• Blocks harmful blue light - Blocks blue-violet light from digital devices and allows beneficial blue light to pass through. ;
• wavefront technology provides the widest possible field of view compared to conventional single vision lenses.

The result is excellent focusing, reduced eye fatigue and protection from blue light. Glasses with this coating are presented in our optics salon, and we can also produce lenses with this coating for your frame.

In our clinic, you will not only be able to undergo a comprehensive examination, after which you will find out the current condition of your eyes and receive recommendations from a professional ophthalmologist, but you will also be able to choose lenses or glasses based on your individual characteristics that can protect your vision from harmful ultraviolet radiation, but also will help keep your vision sharp for many years.

Share with your friends:

Ways to minimize negative impacts

Snow and water have the ability to reflect ultraviolet radiation and increase the negative effect on the visual organs.

Ophthalmologists recommend always wearing sunglasses. It is important to remember that high cloud cover does not protect against radiation. It is also recommended to use lenses, but you should not select them yourself. During the most dangerous time, which lasts from 11 a.m. to 4 p.m., doctors advise staying in the open sun as little as possible. Hats and caps should also be worn.

What to do if you are burned by an ultraviolet lamp

It is forbidden to touch the sore eye or try to open it, as infection or eyelashes may get into the affected areas, which will significantly aggravate pain and irritation. First aid is as follows:

• escorting the patient into a dark room;

apply a bandage and cold to the burned area, without pressing on the eye;

• give painkillers to drink;
• For further transportation, wear light-protective glasses;
• escort the victim to the ophthalmology department of the nearest clinic.

Mild eye burns from a quartz lamp can be treated by applying anti-burn ointments (Kornegel, Tetracycline). If the patient has suffered a moderate injury, the use of anesthetic drops (Naklof, Balarpan, Okomistin) is permissible; in addition to the analgesic effect, the drugs also have an antibacterial effect.

List of medications:

• Solcoseryl is a gel that has an anesthetic effect and accelerates the regeneration process.
• Psilo-Balm is an anti-burn product produced in the form of an ointment. Eliminates swelling, irritation and inflammation.
• Dioxysol - a remedy that effectively fights infections and helps relieve acute pain.
• Dexamethasone, a solution obtained through synthesis, belongs to the group of steroids. It is used to eliminate the consequences of eye damage, and also washes and cleans the sclera. It is recommended to drip three times a day in order to obtain a greater healing effect.
• Diclofenac is a medicine in ampoules. Approved for use in the absence of a pathogenic environment, since the drug belongs to the non-steroidal group. Diclofenac eliminates the cause of swelling and inflammation and has an analgesic effect. Apply one drop per day for 2-4 weeks.

Before using gels, ointments or drops, it is recommended that you familiarize yourself with the side effects of the products used. Certain groups of medications can cause severe allergic reactions and increase the spread of bacteria.

In case of severe damage, assistance is provided only by highly qualified doctors. An experienced ophthalmologist knows what to do and will prescribe the necessary medications and prescribe further treatment procedures.

What is not recommended to do:

• pop blisters that appear;
• put pressure on the eye;
• apply cotton pads (this can heat the orbital area and leave foreign bodies);
• wash the burn (washing will not have a positive effect, but will only cause additional irritation and increase tearing);
• use questionable medications.

UV protection - a problem of the 21st century

Eye protection from ultraviolet radiation has become one of the priorities in medical optics. But sometimes ophthalmologists and optometrists find it difficult to explain to the patient exactly why UV rays are harmful to the eyes. And even more so, doctors are baffled by the questions asked by some patients: why are people talking about the problem of UV eye protection only now? Wasn't there ultraviolet in the sun's rays before?

The fact is that today, due to objective reasons, it is necessary to instill in the population the need for glasses (as well as contact lenses) with UV protection. Two facts force us to pay more and more attention to it: the increase in human life expectancy and the destruction of the ozone layer.

The first means an increase in the total time of eye exposure to ultraviolet radiation. The second is a decrease in the atmosphere’s ability to retain UV rays, including the most dangerous short-wave ones. Despite all attempts to stop the destruction of the ozone layer, the latter continues to “melt”, decreasing in volume by about 12% per decade (in the Northern Hemisphere - by 3%). According to experts, a decrease in the ozone layer by 1% is associated with an increase in the incidence of skin cancer by 4% and cataracts by 0.6-0.8%. The consequences of the thinning of the ozone layer are especially pronounced in the mountains, in southern latitudes in winter.

Thus, the problem of UV eye protection is indeed very acute and really arose only recently - when the conditions in which we have to live today developed.

Unfortunately, people are poorly informed about the dangers of UV to the eyes. A sociological survey conducted in the USA in April 2002 on the initiative and with the support of our company showed that 79% of respondents were aware of the dangers of UV for the skin, but only 6% knew that UV rays can cause eye damage.

Ultraviolet and eyelids

Approximately 90% of UV-induced skin cancers are localized to areas of the skin exposed to direct sunlight: the forehead, ala of the nose, cheekbones, upper lip, chin and eyelids. The latter are “bombarded” with ultraviolet radiation almost constantly when a person is on the street.

The danger of UV exposure to the eyelids is compounded by the fact that due to their proximity to the eyes, creams and lotions cannot be used to protect the skin. All of these drugs contain components whose contact with eye tissue can lead to keratoconjunctivitis.

Acute UV damage to the eyes

The most well-known eyelid lesion caused by high UVB exposure is sunburn, which manifests as erythema and swelling of the eyelids, occasionally leading to blistering and even skin peeling. Among acute UV damage to the tissues of the eye itself, the most common are photokeratitis and solar retinopathy. Symptoms of photokeratitis include pain and the sensation of a foreign body in the eye, photophobia, decreased visual acuity (the appearance of a blurred spot). When examining patients with photokeratitis, low to moderate conjunctival hyperemia and epithelial keratitis involving the superficial layers are usually noted, usually more pronounced in the interpalpebral zone, directly exposed to UV “fire.” In most cases, photokeratitis goes away on its own fairly quickly.

Solar retinopathy develops after intense direct UV exposure. For example, cases of retinopathy are known in people who observed a solar eclipse, in welders, weather forecasters, sunbathing enthusiasts, etc.

Should UV absorber be added to clear lenses?

Many experts believe that the introduction of a UV absorber into clear lenses will only be beneficial, as it will protect the eyes of users and prevent the deterioration of the properties of lenses under the influence of UV radiation and atmospheric oxygen. In some countries where there is a high level of solar radiation, such as Australia, this is mandatory. As a rule, they try to cut off radiation up to 400 nm. Thus, the most dangerous and high-energy components are excluded, and the remaining radiation is sufficient for the correct perception of the color of objects in the surrounding reality. If the cutoff boundary is shifted into the visible region (up to 450 nm), then the lenses will appear yellow, and when magnified to 500 nm, orange will appear.