A fairly common problem for which many people are looking for various solutions is a decrease in night vision. This problem is exacerbated by the increasing age of the population, the increased time people spend outside at night, frequent night travel and especially driving.<\/p>\n
More recently, special expensive night vision masks have been produced for military purposes which electronically amplify the light when it is at low intensity.<\/p>\n
But at the moment, this technology is not accessible to the general public.
To add to the confusion among consumers, there are many companies offering so-called \u00abnight vision goggles\u00bb. However, most experts agree that these claims are unfounded because in reality no coloured lens can improve night vision. To better understand how we can maintain the best possible night vision, let's look at the mechanism of how the eyes adapt to night vision and the conditions that can cause it to decrease.<\/p>\n
The mechanism of adaptation to night vision.<\/strong><\/p>\n \u00a0<\/strong><\/p>\n Often overlooked is the fact that the basic requirement to have vision is light. And really the definition of light is its ability to induce the feeling of sight. There are about 7 million cones in each eye, densely located in the macular region (central part of the retina), which are sensitive to high levels of light and are responsible for daytime vision. By selectively absorbing the light that reaches them, they have the ability to improve image quality and are responsible for most of our visual acuity. In order to achieve the greatest possible visual acuity, it is necessary that the intensity of light reaches above a certain level. Cones are also responsible for the perception of colours. There are three different types of cones, each of which is specialized to selectively detect blue, green and red light in the spectrum. When the light intensity is low the cones are not stimulated, thus dramatically reducing the eyes\u00ab ability to \u00bbdistinguish' colours. This is when the rods are activated.<\/p>\n There are about 120 million rods distributed across the surface of the retina that contain the chemical rhodopsin (a derivative of vitamin A) which is sensitive to very low levels of light intensity. During the day when light levels are high, rhodopsin is deactivated (discolored) causing a delay in the eyes' adaptation to darkness, thus reducing their sensitivity to low light levels.<\/p>\n A simple way to understand the role of cones and rods is to think of them as different films in a camera, each with a different speed. The iris is not able to control this large range of light levels to which the eyes are exposed. This is why the eyes need a fast film (ray for night vision) for low light conditions and a slow film (cone for day vision) for high light levels. The retina \u00abautomatically changes film\u00bb when we are in different light conditions. Dark adaptation is essentially the time it takes for the eye to change its film from slow to fast so that it takes good pictures at night.<\/p>\n Causes of the decrease in night vision.<\/strong><\/p>\n There are basically 5 mechanisms that can cause a decrease in night vision.<\/p>\n 1. Night myopia.<\/p>\n 2. Loss of sensitivity of the photoreceptors of the eye.<\/p>\n 3. Absorption and diffusion of light from internal formations of the eye (e.g. crystalline lens).<\/p>\n 4. Competitive reflections from the environment and glare from nearby light sources (e.g. car headlights).<\/p>\n 5. Looking through dark glasses, windows or windshields.<\/p>\n Let's look at each case separately:<\/strong><\/p>\n 1.\u00a0<\/strong>Night myopia<\/p>\n When the eyes are operating without enough light and contrast (contrast) to see an object clearly, they focus on their own at a distance of about 75 cm. Laboratory studies have shown us that night myopia begins to occur at those light levels at which we have the return of rod function (night vision) and increases to a maximum of 1.35 diopters. Some physicians may prescribe an additional negative correction in patients who report difficulties related to night myopia. However, great care must be taken to avoid overcorrection as the eyes are often in a transitional state between night vision and photopic vision, for example during night driving.<\/p>\n 2.\u00a0<\/strong>Loss of sensitivity.<\/p>\n Total loss of visual sensitivity can be either temporary or permanent. Exposure of the eyes to solar radiation has a temporary and cumulative effect on the subsequent ability to see at night. Daily two- or three-hour exposure of the eyes to the sun can delay adaptation to night vision by more than an hour. But more importantly, this exposure can reduce visual acuity, contrast (contrast) acuity and overall eye sensitivity by 50%. It can even affect the ability to recognize changes in brightness. This is a result of the retention of rhodopsin discoloration for a long time (photochemical substance of the rods) which is the main substance responsible for vision in low light conditions. In this way it has been shown that our night vision is better in winter and worse in summer. This type of visual loss is restored after 24 hours of protection from exposure to sunlight.<\/p>\n It has been shown that sunglasses when designed to absorb 85 - 90 % of the optical spectrum can prevent this type of night vision loss. Those glasses that have an absorbance of 65-50% (lightly tinted) in the optical spectrum are not able to prevent this phenomenon and should not be used in bright sunlight.<\/p>\n Another type of vision loss is macular degeneration. This is a disease of the retina that is the leading cause of visual impairment in America among people over the age of 55. Studies are being conducted by the scientific community to determine the possible role of prolonged exposure to ultraviolet (UV) and short-wavelength blue light in the development of this disease. Many experts believe that UV- and short-wave blue-absorbing sunglasses should be used as a precautionary measure until the relationship between solar radiation and macular degeneration is better analysed.<\/p>\n It should be remembered that no type of sunglasses can protect against the brightness of the sun itself and therefore looking directly at the sun or a solar eclipse can cause irreparable damage to the photoreceptors of the eyes.<\/p>\n Points to remember about night vision when talking to a consumer.<\/strong><\/p>\n - Human eyes take about 1 hour to fully adapt to night vision.<\/p>\n - At night, normal eyes can see a candle from a distance of 16 kilometres.<\/p>\n - At night, colour perception is significantly reduced, and when the eyes are completely adapted to low light conditions, they see no colours at all.<\/p>\n - The rate of car accidents at night is about 4 times higher than during the day.<\/p>\n - If a person who drives at night uses glasses with 50% darkness, it has been shown that their vision is reduced by 60%.<\/p>\n - People over 60 years old need twice as much light as younger people.<\/p>\n 3.\u00a0<\/strong>Absorption and diffusion of light from internal formations of the eye<\/p>\n In infancy the clarity of the internal eye formations is very high. As one grows, various changes occur in the eyes that reduce the amount of light that enters and reaches the retina. The pupils of the eyes become smaller and less sensitive to light. Changes can also take place in the crystalline lens, which turns yellow and becomes less clear. This results in an increase in the diffusion and absorption of visible light, particularly in the low-wavelength blue part of the spectrum. It is believed that some of these changes occur due to photochemical changes that take place from prolonged exposure to ultraviolet rays. The light that diffuses can cause disturbing disturbances at night, especially when under bright lights such as those from oncoming car headlights. People with cataracts in progress usually experience the problem of blinding glare, especially at night.<\/p>\n Laboratory studies have shown that ultraviolet radiation absorbed by the crystalline lens causes it to glare. A recent study of fishermen showed that those exposed to UVB UVB radiation are more likely to have or acquire certain types of cataracts. It has also been shown that removing cataracts can significantly improve symptoms of blinding glare, night vision and visual acuity.<\/p>\n Strong lights, reflections and blinding glare.<\/strong><\/p>\n How well one can see at night depends on how much unwanted light there is from external light sources. Headlights from oncoming cars can momentarily blind the retina from glare, reducing vision until the eye readjusts to darkness. Also reflections that are too often too bright compared to the dark rest of the field can come from wipers, mirrors and the road surface (especially when wet). The effect is similar to someone trying to look out a window at night with the room lights on. The light reflected from the window acts as a veil, making it very difficult to see outwards.<\/p>\n 5.\u00a0<\/strong>Looking through dark glasses, windows or windscreens<\/p>\n Any darkening of the glasses is very much in low light conditions. When driving at night with normal headlights on you can see about a football field in the distance. The effect of tinted glasses (of any colour) is to reduce this distance, the darker the glasses the shorter the distance one can see. The problem is even greater in older people.<\/p>\n How one can maintain excellent night vision<\/strong><\/p>\n protecting his eyes from the sun?;<\/strong><\/p>\n Based on the above information, there are a number of things that one can do to improve their night vision. So to improve night vision, sunglasses should be used during the day. These glasses should briefly meet the following criteria:<\/p>\n - Sunglasses should stop enough light from the visible spectrum to protect the sensitivity of the retina at night.<\/p>\n - Sunglasses should not be too dark so that they do not reduce visual acuity during use.<\/p>\n - Sunglasses should fully protect against UVB radiation, which causes photokeratitis (snow blindness) and has been linked to the development of cataracts.<\/p>\n - Sunglasses should fully protect against UVA radiation, which is believed by some research scientists to be an aggravating factor in the development of cataracts and certain retinal abnormalities.<\/p>\n - Sunglasses should reduce the transmission of low wavelength blue light, which some research scientists believe may contribute to macular degeneration and irreversible loss of retinal sensitivity, without significantly distorting colour perception.<\/p>\n Sunglasses should fit the face well and look good so that the wearer uses them as often as possible, which increases their protection.<\/p>","protected":false},"excerpt":{"rendered":" \u0388\u03bd\u03b1 \u03b1\u03c1\u03ba\u03b5\u03c4\u03ac \u03ba\u03bf\u03b9\u03bd\u03cc \u03c0\u03c1\u03cc\u03b2\u03bb\u03b7\u03bc\u03b1 \u03b3\u03b9\u03b1 \u03c4\u03bf \u03bf\u03c0\u03bf\u03af\u03bf \u03c0\u03bf\u03bb\u03bb\u03bf\u03af \u03c8\u03ac\u03c7\u03bd\u03bf\u03c5\u03bd \u03b4\u03b9\u03ac\u03c6\u03bf\u03c1\u03b5\u03c2 \u03bb\u03cd\u03c3\u03b5\u03b9\u03c2 \u03b5\u03af\u03bd\u03b1\u03b9 \u03b7 \u03bc\u03b5\u03af\u03c9\u03c3\u03b7 \u03c4\u03b7\u03c2 \u03bd\u03c5\u03c7\u03c4\u03b5\u03c1\u03b9\u03bd\u03ae\u03c2 \u03cc\u03c1\u03b1\u03c3\u03b7\u03c2. \u03a4\u03bf \u03c0\u03c1\u03cc\u03b2\u03bb\u03b7\u03bc\u03b1 \u03b1\u03c5\u03c4\u03cc \u03b5\u03c0\u03b9\u03b4\u03b5\u03b9\u03bd\u03ce\u03bd\u03b5\u03c4\u03b1\u03b9 \u03bc\u03b5 \u03c4\u03b7\u03bd \u03b1\u03cd\u03be\u03b7\u03c3\u03b7 \u03c4\u03b7\u03c2 \u03b7\u03bb\u03b9\u03ba\u03af\u03b1\u03c2 \u03c4\u03bf\u03c5 \u03c0\u03bb\u03b7\u03b8\u03c5\u03c3\u03bc\u03bf\u03cd, \u03c4o\u03bd \u03b1\u03c5\u03be\u03b7\u03bc\u03ad\u03bd\u03bf \u03c7\u03c1\u03cc\u03bd\u03bf \u03c0\u03b1\u03c1\u03b1\u03bc\u03bf\u03bd\u03ae\u03c2 \u03c4\u03c9\u03bd \u03b1\u03c4\u03cc\u03bc\u03c9\u03bd \u03ad\u03be\u03c9 \u03b1\u03c0\u03cc \u03c4\u03bf \u03c3\u03c0\u03af\u03c4\u03b9 \u03ba\u03b1\u03c4\u03ac \u03c4\u03b9\u03c2 \u03bd\u03c5\u03c7\u03c4\u03b5\u03c1\u03b9\u03bd\u03ad\u03c2 \u03ce\u03c1\u03b5\u03c2, \u03c4\u03b1 \u03c3\u03c5\u03c7\u03bd\u03ac \u03bd\u03c5\u03c7\u03c4\u03b5\u03c1\u03b9\u03bd\u03ac \u03c4\u03b1\u03be\u03af\u03b4\u03b9\u03b1 \u03ba\u03b1\u03b9 \u03ba\u03c5\u03c1\u03af\u03c9\u03c2 \u03c3\u03c4\u03b7\u03bd \u03bf\u03b4\u03ae\u03b3\u03b7\u03c3\u03b7. \u03a4\u03b5\u03bb\u03b5\u03c5\u03c4\u03b1\u03af\u03b1 \u03ad\u03c7\u03bf\u03c5\u03bd \u03ba\u03b1\u03c4\u03b1\u03c3\u03ba\u03b5\u03c5\u03b1\u03c3\u03c4\u03b5\u03af \u03b3\u03b9\u03b1 \u03c3\u03c4\u03c1\u03b1\u03c4\u03b9\u03c9\u03c4\u03b9\u03ba\u03bf\u03cd\u03c2 […]<\/p>\n","protected":false},"author":1,"featured_media":216,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5],"tags":[],"class_list":["post-1709","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-5"],"yoast_head":"
Vision requires an object within the visual field that is either darker or lighter than the surrounding space. Either in the case where we have plenty of light without any object, but also in the case where we have total darkness, the result is the non-smooth performance of the phenomenon of vision. In such cases the eyes tend to focus at a distance of about 75 cm. This phenomenon is known as night myopia. Normal functioning of vision is due to two different types of nerve cells (photoreceptors) in the retina known as cones and rods.<\/p>\n