This article originally appeared on The conversation.
Myopia, or the need for corrected vision to focus or see distant objects, has become much more common in recent decades. Some even consider myopiaalso known as myopia, an epidemic.
That's what optometry researchers estimate about half of the world's population will need corrective lenses to compensate for myopia by 2050 if current rates continue to rise from 23% in 2000 and in some countries less than 10%.
The associated healthcare costs are enormous. In the United States alone, there is expenditure on corrective lenses, eye tests and related expenses could amount to $7.2 billion per year.
What explains the rapid growth of myopia?
I am a vision scientist who has studied visual perception and perceptual defects. To answer that question, let's first explore what causes myopia – and what reduces it.
How myopia arises
Although having two nearsighted parents means you are more likely to be nearsighted, there is not a single myopia gene. This means that the causes of myopia are behavioral rather than genetic.
Optometrists have learned a lot about the progression of myopia studying visual development in young chickens. They do this by putting little helmets on baby chickens. Lenses on the front of the helmet cover the chicks' eyes and are adjusted to influence how much they see.
Just like in humans, if the visual input is distorted, a chick's eyes become too big. resulting in myopia. And it is progressive. Blurring leads to eye growth, which causes more blur, which makes the eye even bigger, and so on.
Two recent studies involving extensive surveys of children and their parents provide strong support for the idea that important driver of the revival that's myopia people spend more time focusing on objects directly in front of our eyes, whether it is a screen, a book or a drawing pad. The more time we spend focusing on something within arm's length of our face, which is called “near work,” the more likely we are to develop nearsightedness.
So as much as people might blame new technologies like smartphones and too much 'screen time' to hurt our eyes, the truth is that even activities as valuable as reading a good book can affect your eyesight.
Outdoor light keeps myopia at bay
Other research has shown that this unnatural eye growth can be interrupted by sunlight.
For example, a 2022 study found that myopia occurs were more than four times as large for children who did not spend much time outdoors – for example once or twice a week – compared to those who were outside daily. At the same time, children who spent more than three hours a day without reading at school or looking closely at a screen were four times more likely to have myopia than children who did so for an hour or less.
In another article, from 2012, researchers conducted a meta-analysis of seven studies who compared the duration of time outdoors with the incidence of myopia. They also found that more time spent outdoors was associated with lower incidence and progression of myopia. The risk of developing myopia decreased by 2% for every hour spent outdoors per week.
Other researchers have reported and advocated for similar effects much more time outdoors and changes in early childhood education to reduce the prevalence of myopia.
What drives the epidemic
That still doesn't explain why it's rising so quickly.
Worldwide is one Much of this is due to rapid development and industrialization of countries in East Asia over the past fifty years. Around that time, young people began spending more time in classrooms reading and focusing on other objects very close to their eyes, and less time outdoors.
This is also what researchers say observed in the North American Arctic after World War II, when education was made mandatory for the indigenous population. Myopia rates for Inuit went from single digits before the 1950s to over 70% in the 1970s, when all children first started school.
Countries in Western Europe, North America and Australia have shown increased risk of myopia in recent years, but nothing close to what has been observed recently China, Japan, Singapore and some other East Asian countries. The two main factors that have been found to lead to increased myopia are: read more and other activities that require focusing on an object close to the eyes and reducing time spent outdoors.
The increase in the number of cases of myopia will probably have its worst consequences in 40 or 50 years it takes time so that the young people now diagnosed with myopia are experiencing the most severe vision problems.
Treating myopia
Fortunately, only a few minutes a day with glasses or contact lenses that correct blur stops the progression of myopiaTherefore, early vision testing and vision correction are important to limit the development of myopia. In some countries, eye checks for children are mandatory, like Great Britain And now Chinalike most US states.
However, people with high myopia do increased risk of blindness and other serious eye problems, such as retinal detachment, where the retina pulls away from the back of the eye. The chance of myopia-related macular degeneration increases by 40% for each diopter of myopia. A diopter is a unit of measurement used in eye prescriptions.
But there seem to be two reliable ways to compensate for or slow down these effects: spend less time focusing on objects close to your face, like books and smartphones, and spend more time outside in bright, natural light. Since the first is tough advice to follow in our modern age, the next best thing you can do is take regular breaks – or perhaps spend more time reading and scrolling outside in the sun.
