The planet’s vision is getting worse: 50% of the population will have myopia by 2050

In some classrooms in China, a type of railing anchored to the desk separates the child from the table and keeps their view of the book at a safe distance. In other schools, students wear a hat with a ball that balances on the brim: if the ball falls off, it means that the kids have lowered their heads too much and have gotten too close to the notebook. All these initiatives are designed to combat the rise of myopia, which is especially rampant in some Asian countries and expanding throughout the globe. Experts warn that, fueled by the overuse of screens and the decline in outdoor activity, half of the world’s population will have myopia by 2050.

This condition is a common disorder of visual focus due to an enlargement of the eye. “It’s an eye that grows larger than its age. The axial length, which is the distance between the cornea and the retina, increases and the focusing point is in front of the retina [and not on it],” explains Silvia Alarcón, a pediatric ophthalmologist at Vall d’Hebron Hospital in Barcelona. The axial length of a healthy eye is usually around 23 millimeters, but in a myopic eye it can reach 30 or 35 millimeters. In practice, this deformation of the eye causes light rays to refract incorrectly and the point of focus to be deviated, resulting in blurred vision of distant objects.

There are different degrees of myopia, but the experts who spoke to EL PAÍS point out that after three diopters “it is difficult to lead a normal life” without correction, such as glasses, for example. And the greater the degree of myopia — such as magna myopia, when a person has refraction of more than six diopters —, the greater the risk of developing pathological ocular changes that can cause irreversible vision loss, such as cataracts, glaucoma, retinal detachment and myopic macular degeneration. In 2010, uncorrected refractive error was estimated to be the most common cause of distance visual impairment and the second most common cause of blindness worldwide.

“It is already a public health problem,” warns Miguel Ángel Sánchez Tena, researcher at the Department of Optometry and Vision at the Complutense University of Madrid. In countries such as China, South Korea, Japan and Singapore, around 80% of children who finish secondary education suffer from this visual defect and of them, between 10% and 20% are very nearsighted, so they have more risk of developing a potentially blinding pathology.

But the rise of myopia is not limited to Southeast Asia. The planet’s vision is getting worse. A scientific review found in 2016 that, at the beginning of the 21st century, 1.4 billion people suffered from myopia and predicted that by 2050 that number will rise to 4.7 billion. That’s the equivalent to almost half of the world’s population, although there are differences by territory: by mid-century, the prevalence of myopia in East Africa will be below 23%, while in high-income countries in Asia and the Pacific, two out of three people are predicted to suffer from the condition.

“We are noticing the increase in the number of cases in children’s consultations: there are more people with myopia, and it is progressing faster,” says Luis Fernández-Vega Cueto-Felgueroso, ophthalmologist at the Cornea and Crystalline Unit of the Fernández-Vega Institute. In Spain, recent research led by Sánchez Tena and Cristina Álvarez Peregrino showed that the prevalence of myopia in children between the ages of five and seven stands at 19%, but by 2030, it will reach 30%.

Multifactorial origin

According to Sánchez Tena, the rise in myopia is due to a multifactorial origin. It is influenced by genetics — although it is not clear which genes are involved —, environmental factors and also race, with Asian people at higher risk. “There is a genetic component: children of parents with myopia will have a higher risk of developing it. But it is also influenced by work and digital devices,” says Sánchez Tena. Age is also another risk factor: the condition is more likely to progress more rapidly in children who have refraction of 1.25 diopters between the ages of six and seven.

Australian researchers who estimated the prevalence of myopia by 2050 agree that the projected rise is due, above all, to environmental factors related to upbringing, principally lifestyle changes resulting from a combination of decreased time outdoors and increased near-vision tasks. The scientists say that genetic factors play a role, but this variable alone could not explain the high rate of expansion of myopia in the world.

Among other environmental factors, the scientists also point out that “so-called high-pressure educational systems, especially at very young ages in countries such as Singapore, Korea, Taiwan, and China, may be a causative lifestyle change, as may the excessive use of near-vision electronic devices.” Other causes listed are light levels, which may be related to the time children spend outdoors, or even diet. “Light from screens, ocularly, does not damage the eye. But the overuse of screens does favor [these optical problems]. If we used the screens in a good way, there would be no problem. But children are abusing them more today,” notes Fernández-Vega Cueto-Felgueroso.

Alarcón also claims the overuse of screens and less exposure to the sun is responsible for the rise in myopia. “When we look up close, we make an extra effort to focus and that gives [the eye] a stimulus to grow. There is no study that shows that one factor influences more than another, but there are studies in China that show that teaching outdoors, to expose children to ambient light, helps reduce the progression of myopia,” says Alarcón. The explanation, according to studies with animal models, is that, due to the brighter levels of light outside, the release of retinal dopamine increases, which helps reduce axial length.

Delaying progression

Myopia is usually detected in childhood and can increase until adulthood, around the age of 22. Ophthalmologists point out that it is increasingly diagnosed at younger ages, but it is also in those phases of life when it is best to take action because the eye is still forming and there is more plasticity. There are several approaches to slow down the progression, explains Alarcón: “We have special crystals that blur the peripheral area of the retina, and this activates receptors that prevent it from progressing so much. We also have contact lenses and glasses that squeeze the cornea to shorten the eye.”

Another option, he points out, are atropine drops: “These drops, at very low concentrations, slow down the progression because they are believed to act on those areas of the retina. The problem is that they are not marketed and right now they are used as a magistral formula [a medicinal product prepared in a pharmacy following a prescription for an individual patient] because there is no way we can find a laboratory that markets such diluted drops.”

This is not a cure, but “if the progression can be slowed down, it is already very important,” says Sánchez Tena: “A myopic eye does not become normal again. But childhood is a window of opportunity and even if you don’t completely stop progression, the more you delay it, the better.” Glasses, contact lenses or corrective surgery eliminate blurred vision, but they do not stop the eye from growing.

Beyond the global vision problem, experts are especially concerned about the rise of cases of more severe myopia, which can lead to an increased risk of more complex optical pathologies. “Every diopter matters. If it were just to put on glasses and see well, that would be it. But the problem is what happens in the final part of the eye. Your eye is going to be myopic all your life, even if you don’t have to use correction,” says Sánchez Tena. For example, highly myopic people are 20 times more likely to suffer retinal detachment during their lifetime than someone with normal vision. “The retina that covers the inside of the eye becomes so tense that holes can appear and there is a greater risk of retinal detachment,” explains the ophthalmologist.

Given this risk, experts are calling for urgent action. In terms of prevention, says Alarcón, “the only effective thing is to do more outdoor activities while reducing near-vision tasks.” Fernández-Vega Cueto-Felgueroso, meanwhile, calls on people to follow “the 20-20-20 rule: every 20 minutes, look for 20 seconds at something 20 feet away, which is about six meters. We must try to ensure that young people control the use of near-vision devices and that they have good light, that they are not in the dark and that they take a break to look into the distance.”

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