Abstract: if the thickness of a lens is 5mm and the thickness of a pair of glasses is 10mm, then 100 pairs of glasses are equal to 1m, 500 million pairs of glasses are equal to 5 million meters, also equal to 5000 kilometers. 2 billion glasses are equal to 20 million meters and 20000 kilometers.
our vague impression is that 8 out of 10 people are short-sighted, so is the real data so?
2 billion people around the world wear glasses. Pay attention! It’s myopia glasses. It is said that this number will soar to 2.5 billion people in 2020. China is one of the countries with the highest incidence of myopia in the world. The number of myopia in China is close to 500 million, that is, one in two Chinese people is myopia. According to the data of 2012, the prevalence of juvenile myopia has ranked first in the world.
regional distribution map of myopia occurrence probability
suddenly want to calculate a mathematical problem: the total length of glasses thickness
if the thickness of a lens is 5mm and the thickness of a pair of glasses is 10mm, then 100 pairs of glasses are equal to 1m, 500 million pairs of glasses are equal to 5 million meters, also equal to 5000 kilometers. 2 billion glasses are equal to 20 million meters and 20000 kilometers. There is nothing wrong with
, that is, stacking glasses all over the world can make half a circle around the earth. Of course, this is only the case when 2 billion people each have only one pair of myopia.
the lens thickness of people all over the world is equal to 563 Mount Everest. You are right. The climbing partners are stunned.
growth! 60 years ago, 10% ~ 20% of Chinese people suffered from myopia. Nowadays, the myopia of young people and young people is 90%, and is becoming more and more young. If there is no effective policy intervention, the incidence rate of myopia in China over the age of 5 will increase to 50.86% to 51.36% by 2020, and the population of the disease will be close to 704 million to 711 million. This figure can definitely outperform the growth rate of GDP.
the increasing myopia in modern society reflects a trend that people spend too much time studying or staring at computers and smart phone screens. Today, with the change of eye habits, the evolution of human eyes is not enough to catch up with the development of intelligent products. Therefore, the key to protecting visual health is to use eyes reasonably and moderately, carry out more outdoor sports and conduct visual examination regularly.