Why is the whole world becoming short-sighted?

When Rosa first opened her eyes the day after her nearsightedness surgery, she couldn't believe she could see the numbers on her alarm clock perfectly clearly. She was 32 at the time, and she hadn't been able to see anything without glasses for 26 years. "When I went to the beach and got into the water, I had to have a visual reference. A red umbrella and a blue one next to it. And when I got out of the water, I had to look for a red spot and a blue one," explains this journalist, illustrating what life is like with ten diopters.

In Catalonia, nearly two million people are short-sighted, and of these, half a million are between 17 and 27 years old, According to data from the Official College of Opticians and Optometrists of Catalonia (COOOC). Overall, it affects 5% of preschool-aged children, 9% of school-aged children, and 30% of adolescents. In fact, myopia is already considered a pandemic by the World Health Organization (WHO) due to its high prevalence rates worldwide. Furthermore, this organization predicts an increase in cases by almost 30% in just one decade: from 2.6 billion in 2020 to 3.36 billion in 2030.

Myopia is a refractive error in which the shape or length of the eye prevents light from focusing directly on the retina—it focuses directly in front of the retina. This causes distant objects to appear blurry, but close objects to appear blurry. The most common type of myopia appears during school age, around the age of six, and gradually increases as children grow older. This is the case of Juli, a screenwriter by profession, who recalls that as a child, he couldn't see the blackboard in class, one of the most obvious signs when it comes to detecting this vision problem.

"Having low myopia isn't a problem, even if the child or adult needs to wear glasses, contact lenses, or consider surgery," notes Joan Pérez Corral, an optician-optometrist who heads the COOOC's Myopia Control Committee. However, eyes with a diopter of six or more are considered at risk for associated conditions, such as glaucoma, macular degeneration, retinal detachment, or premature cataracts, which could lead to vision loss.

"My whole family, both on my father's and mother's side, wears glasses," explains Juli. Aside from a genetic component, there is a very important environmental and lifestyle risk factor. For example, 6 out of 10 university students (62.5%) between the ages of 17 and 27 are myopic in Spain and have more diopters than the previous generation, according to a Vision and Life Association reportThe rate is higher among women (65.4%) than among men (54.7%). In addition, the more time we spend studying, the more likely we are to develop myopia. study by the University of AlcaláConducted among medical students, of the 17 volunteers recruited, 9 were myopic at the initial assessment and 11 after five months of follow-up, a statistically significant figure.

The more education, the more myopia

The correlation between length of education and difficulty seeing objects at a distance is a constant worldwide, especially in certain regions and demographic groups. Chinese researchers from Sun Yat-sen University analyzed government reports from 50 countries in Asia, Europe, Africa, Oceania, North America, and Latin America. They found that the prevalence of myopia tripled between 1990 and 2023. This phenomenon is associated with several factors, such as: living in East Asia (35%) or urban areas (29%), being female (34%), and adolescence (4).

In countries like China, Singapore, and South Korea, myopia is a real public health problem, with rates that could reach 54% by 2030 and 69% by 2050 among younger people. The causes, according to the study, published in the British Journal of Ophthalmology, could be rapid economic development and the early introduction of formal education. In contrast, African populations have a lower prevalence of myopia, likely attributed to lower literacy rates and a later start to formal education.

Joan Pérez Corral is also an associate professor at the Faculty of Optics and Optometry of Terrassa (FOOT) of the Polytechnic University of Catalonia (UPC). This center is carrying out the CISViT project (Terrassa Children's Visual Health Cohort), which provides information on the incidence and progression of myopia in 2,000 children between the ages of 8 and 16 from public and private schools in the city. "One of the results of the study is that, although we always keep in mind that myopic children are children with disabilities and a high economic status, those with a higher incidence of myopia are those from less fortunate families," explains this doctor in optical engineering. The hypotheses could be multiple: from the cost of treatments—between 600 and 1,000 euros per year—to the fact that, with the democratization of mobile phones, children with fewer resources spend more time indoors because they lack the opportunity to engage in outdoor activities.

Recently, Korean researchers have published in the journal JAMA Network Open a meta-analysis of 45 studies, in which more than 330,000 people aged 2 to 19 participated, suggesting that increasing screen time by one hour a day increases the risk of suffering from this eye condition by up to 21%, both in Asian countries and outside the continent. The COOOC, for its part, warns that, currently, more than half of young people (55.7%) have mobile phones before the age of 12, and more than 95% look at them in bed, with the lights off, before going to sleep. Blue light on the retina can be more harmful in dark spaces, according to the experts, who also highlight that, in Spain, young people do not spend even an hour a day participating in outdoor sports activities.

"There is no scientific evidence that electronic devices, by themselves, are to blame for myopic progression, but rather the current habit of looking at everything up close, which forces the visual system to adapt," said the head of the COOOC's Myopia Control Department. And that also includes spending five hours straight "watching TikTok videos." That's why, during Covid-19, when exposure to sunlight was reduced due to lockdown and we spent so many idle hours at home, vision deterioration accelerated across the entire population. Myopia, in particular, doubled in children and adolescents.

Correct myopia

Therefore, the myopia epidemic involves genetic, environmental, demographic, and lifestyle factors, so there is no single approach to treatment. The most common optical correction is the use of glasses or contact lenses. A low dose of atropine eye drops, a drug used to dilate the pupil and relieve eye pain, before bedtime has been shown to slow the progression of childhood myopia. But Joan Pérez Corral warns that "the higher the concentration, the greater the effectiveness, but also the greater the side effects."

For this reason, some parents opt for non-pharmacological treatments, such as ophthalmic lenses or contact lenses with special designs for myopia control. The non-pharmacological treatment with the greatest scientific evidence currently is orthokeratology, also known as Ortho-K or pajama contact lenses, which mold the shape of the cornea while the patient sleeps, and the effect lasts all day. "We adapt them starting at age 6-8 to try to slow myopic progression, although in the process, children learn not to have to wear glasses during the day to see well."

Surgical treatments are an option when myopia has already stabilized. The most notable are the implantation of intraocular lenses—with or without removing the lens—and laser refractive surgery with techniques such as LASIK, PRK, or SMILE, which involve reshaping the cornea. This treatment is often used to correct the myopia, although it may not achieve two diopters due to convenience and cost—approximately €1,800 for both eyes.

"I remember waiting longer for the anesthesia to take effect than for the laser itself. That day you leave the hospital, your vision is clearer than when you came in, but then your vision starts to blur and you feel really bad for three days because you want to keep your eyes closed the whole time." But after a month, I was completely recovered.

It may reappear

This doesn't mean the defect won't reappear, which is what happened to Rosa 15 years after her LASIK surgery. "Starting in my 40s, my myopia combined with presbyopia, and I needed glasses again, but I have 2 or 3 diopters; they've never gone back to the 10, at which I felt visually impaired," she says. Much of her family is also nearsighted.

The UPC expert also cites a revolutionary treatment that began to be widely used in China: red light. The child looks at a laser device for five minutes from the comfort of his home; he must continue to wear glasses, but the progression of myopia is slowed. The emergence of cases with retinal damage, "perhaps due to overexposure or because some technical feature needs to be adjusted," has led to a step back in evaluating the safety of a very promising treatment.

As a final message, Joan Pérez Corral emphasizes the importance of having an eye exam "ideally before the age of six," because that's the age at which myopia begins to appear in schoolchildren. Unfortunately, there are no established protocols in the public health system, so he recommends going "to an optician, a pediatric ophthalmologist, or, better yet, both professionals, because each one sees different things."