How does short-sightedness develop? Latest findings from science and research

infinitelearning (63)in #steemit-austria • 6 years ago

Short-sightedness has developed into a global disease over the decades. The alarming thing, however, is that modern medicine does not yet know a hundred percent of the answer. If the epidemic continues to develop, more than 1 billion people could go blind by 2050. I was frightened by these figures and I started looking for studies to explain the frightening development.

At present, about a quarter of the world's population are affected by myopia. Particularly in Asia, the figures are reaching unprecedented levels. In concrete terms, 95 percent of all young people under the age of 20 are short-sighted in some parts of Asia. For some, this is simply due to the demographic class and its inherited predisposition. According to the widespread opinion of the population, Asians have worse eyes.

However, this is only a limitedly satisfactory statement: although both parents were never plagued by short-sightedness in many families, the children nevertheless developed an increased tendency to short-sightedness, and this is not an isolated case - according to the researchers. Recent findings from science and research show that a tendency towards short-sightedness through inheritance occurs only in about 3 % of all affected persons.

What is short-sightedness?

Our eye has the ability to transmit shapes and colors to our brain through the optic nerve. First the light impulse falls into our eye, then through the cornea and then through the lens, where the image is mirrored. Afterwards, the inverted image hits our retina, where it is passed through the optic nerve to our brain and reflected back again. Short-sightedness is usually caused by a defect in the refraction of the lens caused by a too long eyeball. Basically, the lens can adjust itself to a certain extent by stretching or shrinking, but it cannot correct a too long eyeball.

At that time, my ophthalmologists explained to me that this is related to the growth of the body and that the length of the eyeball changes due to growth spurts. But I thought back then that this was not quite true. Because even now, at the age of 22 years, when my body should have stopped its growth spurts, my vision is still changing.

What is the cause?

For the first time in 2010, the leading research team around Chris Hammond discovered a gene that could be associated with myopia. In doing so, he examined several 10,000 people and found a striking gene called RAS GRF-1 on chromosome 15, and almost at the same time Caroline Klaver, a researcher in Rotterdam, discovered a gene on chromosome 15 that she believed was responsible for short-sightedness. A short time later, however, the disillusioning answer: In addition to the two genes, about 100 other genes were found within a short time, which caused discrepancies between the genetic researchers.

The geneticists have not yet been able to determine which of them are actually decisive. The researchers decided not to focus on the genes, but on the lifestyle of the growing mass of short-sighted people. Generally speaking, the experts discovered a significant proportion of short-sightedness among students and academics. The reason for this is frequent reading and working close by, the dramatic result is short-sightedness. Already in the 1960s, information campaigns were launched nationwide to educate pupils and students about the correct reading distance.

But already in the 19th century, Hermann Cohn gave instructions on the correct visual distance under the title "Textbook of Hygiene of the Eye" and appealed to the school organisations to set up classrooms that would literally force the children to the correct visual distance. In Singapore, for example, the authorities have been financing studies for years to investigate the influence of a false visual distance on vision. The facts are obvious: Due to the large amount of media consumption, over the years children have been more and more tempted to spend most of their day in their own homes instead of playing outside. My grandmother always used to say that television would make you look bad. However, according to a new study, media consumption is not the decisive factor, but something completely different.

The true reason for myopia

Researchers have found out that the eye grows in length when working close up, at least only for the duration of the close up. The exact connection why our eye does this is still the subject of ongoing discussion and unexplained. In 1997, Donald Mutti conducted a study of 4000 healthy children to question them about their lifestyle habits. After 5 years the frightening result: 1 in 5 children suffered from myopia. Mummy said in an interview that he would be glad to have included a question almost accidentally in the study at that time, which probably explains the current development of short-sightedness.

The real reason for this is not media consumption, but a stay outdoors. The more time a child spent outside, the lower the risk of developing myopia. At the same time, Ian Morgan from Australia came to a similar conclusion that the time spent outdoors was a key factor. The results of the studies are all the more astonishing: Professor Donald Mutti found out that a child with parents who had already been exposed for only 2 hours a day could reduce the risk of a disease from 60% to an astonishing 20%. The early years in childhood are the critical ones, and the effects of hours of reading or watching television seem to disappear. The decisive criterion is not fresh air or outdoor movement, but the exposure to natural daylight.

Daylight deprivation and the associated lack of blue light lead to a deformation of the eyeball and thus to short-sightedness. An interior often did not exceed 1,000 lux while a sunny summer day could often reach 100,000 to 150,000 lux. In addition, the molecule dopamine is also believed to be decisive for short-sightedness: If the eye is exposed to blue light, the retina releases dopamine and begins to form a natural spherical shape, while red light leads to the oval shape that is harmful to myopia. The more time spent outdoors, the more dopamine would be released and the lower the risk of short-sightedness developing in children.

sources:

https://www.theguardian.com/technology/2010/sep/12/dna-research-short-sight-treatment

https://www.nature.com/news/the-myopia-boom-1.17120

This article is my translation into English. You can find my original german article here.