Vision is one of the most remarkable abilities of most living beings. It is one of the five human senses, but it gives us much more information than all the others combined. Its only drawback is the inability to function normally in the dark. This creates specific difficulties for people and forces them to use special night vision devices. Until recently, correcting the lack of vision inherent in nature was impossible. However, science does not stand still, and every year, more and more information proves the possibility of people developing the ability to see at night. You will learn which of these is a myth and which is reality from our article.

What is night vision?

Day vision is available to everyone who does not have serious diseases, pathologies, and other problems with the visual system. However, in addition to this concept, there is also night vision. It is available to some species of mammals, birds, insects, and reptiles. The most famous users of this vision are hedgehogs, lemurs, bats, wolves, owls, various types of moths, geckos, and frogs. A person is not initially endowed with the ability to see well in the dark. However, there are exceptions caused by various genetic changes in the body.

Night vision is a unique ability. It has many distinctive features that are not characteristic of daytime vision. Among them, experts identify the three most essential nuances that should be studied in more detail.

Critical features of night vision:

1. Increased photosensitivity. This feature of night vision is its main difference from the ability to see during the day. The improved performance is explained by the lack of illumination, due to which the photosensitivity of cones (conical peripheral processes of retinal cells) becomes much lower than the photosensitivity of rods (cylindrical peripheral functions of retinal cells). This circumstance leads to photosensitivity at night becoming hundreds of times higher than during the day.
2. Reduced resolution. This feature can be observed in people who have problems with daytime visual acuity. In the case of night vision, the condensed key is not due to any issues but to a change in the density of the distribution of rods and cones on the retina. For the former, this indicator is much less than for the latter, which is why a similar effect occurs.
3. Lack of ability to determine colors. This feature is another proof of the uniqueness of night vision. At night, the flow of photons of light is less powerful than during the day. Because of this, the work of cones almost wholly stops, and vision is provided exclusively by rods. This leads to the fact that it is much more difficult to distinguish one color from another at night than during daylight hours.

Features of human vision

Man cannot see in the dark. This is due to the peculiarities of the work of his visual system, which is an absolute miracle of nature. One of its main elements is the eyes. They have a rather complex structure, thanks to which a person can visually perceive information. The process of functioning the eyes is also tricky and confusing. In it, an important role is played by several organs at once, which together form an image of the area being examined. In most people and some mammals, the eye can only see light in a specific part of the spectrum. So scientists proved that a person sees light radiation well in the wavelength range of 400-700 nanometers. At the same time, he does not notice the light in the infrared range (750-1400 nanometers). That is why people cannot usually see in the dark without using thermal imaging equipment or night vision devices.

The process of functioning of human vision:

1. In the first stage, the light reflected from various surrounding objects enters the eyes. Immediately, it passes through the convex cornea, due to which it is refracted.
2. In parallel with this, the pupil adapts to the current light conditions. If there is little light indoors or outdoors, then it expands. The reverse process (narrowing) is observed if a bright light source is nearby.
3. Refracted light passes through a dilated or constricted pupil. After that, he inevitably falls on the lens. The latter changes its form, adjusting to current needs. This is because the ciliary body is connected to the lens by almost invisible connecting threads. Most of it is made up of blood vessels and muscle tissue. When the latter is relaxed or tense, the shape of the lens is corrected (depending on how far the observed object is located).
4. The lens has corrected its shape and focuses light on the retina. It has a multilayer structure consisting of layers of light-sensitive tissue and pigment epithelium. Its thickness differs in each part, varying from 0.07 mm to 0.5 mm.
5. After that, special receptors of the eyeball, which are called rods and cones, come into play. They provide the transmission of light and its transformation into a nerve impulse.
6. The generated nerve impulse transmits data to the human brain, which creates the final image.

The complexity of the functioning of human vision requires the ideal state of each organ involved. If there are imperfections, the visible image's quality is reduced. In most cases, it becomes fuzzy, which creates many problems for a person.

A similar structure and functioning of the visual system is observed in some mammals. This feature allows scientists to conduct numerous experiments with vision, achieving quality improvements and giving it new features (for example, the ability to see in the dark).

Can a person get night vision?

The ability of some animals to see in the dark, haunted people for many centuries. They repeatedly tried to develop such skills in themselves, but all efforts failed. Scientists of our time are making another attempt. They involve modern business technologies and expect to succeed with their help. It is still being determined how far they will advance in this work, but the first results of their activities are already available to the public today.

Theoretical justification

Nature has arranged it so that people's visual systems can only provide good visibility with lighting. This fact was proven many years ago, and no evolutionary processes could improve the situation. In this regard, the ability to see at night will not be able to appear naturally. It also cannot be developed by special training and various procedures. Nevertheless, people are stubborn creatures who will try to achieve their goals by any means. Thanks to this, they are already trying to artificially provide the human eye with the ability to see in the dark.

Theoretically, you can change anything in a person by rearranging the DNA. This method is quite dangerous, and it is unlikely that anyone will dare to use it in the coming decades. However, scientists from various universities have carried out a complex theoretical study, thanks to which they found that it is enough to condense the DNA strand in the photoreceptor cells of the rods (peripheral processes of the light-sensitive cells of the retina) to achieve a reduction in light scattering. This will lead to an increase in the transparency of the retina with a subsequent improvement in the quality of night vision. This theoretical method has been partly tested on small rodents, and its results met all the scientists' expectations. However, in the case of a person, the situation can be radically different.

Another option for improving visibility in the dark is to convert infrared light into an analog with a wavelength accessible to the human eye. Theoretically, this can be done by introducing unique mechanisms into the organs of vision. There is also the possibility of using special materials with this ability. In practice, everything is much more complicated than in theory, so only some methods are actively developed by scientists. Nevertheless, specific shifts are already taking place, giving hope for the successful completion of the path.

Possibilities of nanotechnology

Improving a person's night vision by changing DNA is not optimal, as it is associated with severe risks. The same can be said about the variant with the implantation of various mechanisms into the human visual system. In this regard, the only way worthy of attention is by using a material capable of converting infrared radiation into light waves visible to humans. This option provides for the need for developments in the field of nanotechnology.

Nanotechnology is a self-formed field of science. It explores the atomic and molecular structure of everything in nature and, with the help of various manipulations, makes certain adjustments to it. In the case of human vision and endowing it with the ability to distinguish infrared waves, scientists decided to make such adjustments to various substances. On their basis, they created a unique material called Upconverting nanoparticles (UCNP). It consists of several chemical elements (ytterbium, erbium) which belong to the lanthanides. They are pretty rare on our planet, so they are costly. This dramatically complicates the creation of a large amount of nanomaterial, which may become very popular.

UCNP has unique properties. It can transform the photons available in infrared light into light radiation with a different wavelength. This makes it ideal for creating night vision in humans. The conversion of IR light occurs without the appearance of any side effects, which reduces the danger of the nanomaterial to human vision. A significant problem for scientists was choosing the optimal way to introduce UCNP into the visual system. After numerous experiments on animals, the injection option was selected.

Animal testing

Scientists on rodents tested the nanomaterial created in scientific laboratories. These mammals are ideal for such purposes, as they have approximately the exact structure of the visual system as humans. After UCNP was injected into the eyes of mice, the nanoparticles contained in the material began to transmit the light that the rodent sees to light-sensitive pigments. The latter plays an essential role in the vision of most mammals and helps them see various objects. These pigments are located in photoreceptors, cells in one of the layers of the retina. Their combination with photosensitive pigments made absorbing light of different shades possible. This, in turn, led to the formation of nerve impulses transmitted to the mouse's brain.

The test results showed that the rodents injected with UCNP could see light in the IR range. This was proven by numerous experiments in which mice were tasked with finding a way out of a maze. Light guides for rodents used IR radiation, which they could see after injections. Thanks to this ability, most of the experimental mice completed the task. Such testing proved the effectiveness of the created nanomaterial. However, testing it on the human visual system took time. The main problem was the differences between the organs of vision of rodents and humans. In mice, there are only three photosensitive pigments, two responsible for creating a color image and 1 for black and white. People have these elements 4 (3 + 1). With the help of various manipulations, scientists managed to add the genes of one additional pigment to rodents. This made the eyesight of mice as close as possible to a human's. After that, repeated experiments with UCNP were carried out, but they could have brought better results.

To remedy the situation, scientists working in several directions have joined forces. The result of their collective work was a report that indicated a possible reason for the unsatisfactory test results. Scientists assumed that blue light, into which UCNP converted IR light waves, was to blame. The morning of this shade carries more energy than infrared. Because of this, the nanomaterial used first absorbed part of the photons of the IR study and only then took on blue light particles. This feature prevented the mice's visual system from processing enough infrared radiation to provide normal vision in the dark.

The scientists conducted the following experiments with a slightly modified nanomaterial, which now converted infrared light fluxes into green light. The fact is that the light-sensitive pigments of rodents and many other mammals are more sensitive to a green tint, which gave hope for the successful completion of the experiments. To further increase the chances, it was decided to coat the UCNP particles with a particular protein. It must combine with sugar molecules on the membranes of photoreceptors and remain with them for several weeks. The experiments proved the scientists' correctness, after which it was possible to start re-testing the rodents.

This time, mice injected with UCNP and rodents without eye injections were asked to swim through the maze and find a platform hidden under the water's surface. It was possible to safely take a break from swimming and be above the water level. Initially, such a platform was illuminated by ordinary light, which all the mice saw. Each of them quickly discovered the opportunity to escape the water and did not experience any problems with this. However, when the platform was moved to a different location and illuminated with IR light only, only the UCNP-injected rodents completed the task. This experiment proved the scientists right, and their discovery became an essential scientific event.

Security Questions

The main problem with any novelty successfully tested on animals is its transfer to humans. In this case, every little thing must be considered before testing. Ongoing research and experiments with mice have encouraged scientists. During the entire testing cycle, the experimental animals did not reveal any problems with vision and body health. The nanomaterial injected into their eyes was excreted naturally after 9-10 weeks.

The only thing that remains a mystery is the biocompatibility of UCNP with various substances found in the human organs of vision. Because of this, developing any negative consequences for the eyes and multiple body systems is dangerous. In this aspect, a severe drawback is using such chemical elements as ytterbium and erbium to create a nanomaterial. In a relatively short period of testing, they did not harm mice, but in the long term, these substances can adversely affect the functioning of various systems. In the case of a more vulnerable human body, the consequences can be much worse.

Another critical issue is the inorganic nature of UCNP. Because of this, it is not always possible to predict the consequences of using such material. Now active development of a similar organic nanomaterial is underway, which will potentially be safer for humans.

The future of night vision in humans

The ability to see well at night is an inevitable phenomenon available to people in the coming decades. New developments in medicine and nanotechnology are already being actively tested, which will become the basis for future discoveries. In the next few years, not only rodents but also dogs will become the main object of testing the effectiveness of the invented nanomaterial. It is expected that UCNP testing will be conducted on service dogs. If this experiment succeeds, people will get a unique four-legged assistant who will more effectively execute commands and bring significant benefits.

After testing on animals, it will finally be the turn of humans. One day, scientists will be able to inject a nanomaterial into the human eye, allowing it to see light in the infrared range. Having studied the consequences for the body and ensuring that no adverse effects are observed, it will be possible to start mass improvement of human vision. Military personnel will be the first users. It was for them that this technology was initially developed to create a better and simpler alternative to night vision devices.

Shortly, scientists expect that the ability to see in the dark will become available to everyone. This turning point will change our understanding of the dark time of the day and the new opportunities opening up for humanity. Another application of this development will be the treatment of many diseases of the visual system. Due to the possibility of combining nanomaterial with various drugs, it will be possible to more effectively influence photoreceptors, light-sensitive pigments, and other optical system components. Similarly, it will even be possible to eliminate various pathologies (congenital or acquired) that prevent a person from having normal vision.

People endowed with the ability to see in the dark will become indispensable workers. They will be able to perform their labor duties in the dark and work efficiently and safely in conditions of poor lighting. In addition, night vision will increase the efficiency of rescue operations, security measures, and other activities. The ability to see in the dark will give everyone many additional opportunities that can be used to achieve personal goals. This will positively impact all of us and bring people closer to making amazing discoveries.

Humans are the only creatures on the planet trying to change their nature. They do various plastic surgeries, change sex, and correct congenital pathologies. Now it comes down to vision. Man's inability to see in the dark will soon become a defect of the past. Already, many experiments are being carried out in the field of nanotechnology, which in the future will give people the ability to see at night. It is still being determined how quickly a breakthrough in this direction should be expected, but we can confidently say that success will be achieved sooner or later. In this case, our daily life will change dramatically, and we can use the nighttime more fruitfully.