Japan’s Myopia Epidemic

Japanese schoolchildren are spending more time with screens than ever before.

But the tablet is only one piece of a much larger story—a story about how modern childhood may be changing the human eye.

When Digital Childhood Changes the Eye

Imagine an ordinary Japanese schoolchild.

A smartphone on the way to school. Several hours of classes. A tablet for part of the school day. After school, messages, videos, games or homework. In the evening, another screen—often held just a few inches from the face.

For much of the day, the eyes are focused on objects at close range.

Now imagine this happening not to one child, but to millions.

In Japan, myopia has become more than an individual vision problem. It is increasingly a matter of public health.

Current estimates suggest that roughly 5.5 million Japanese children between the ages of 5 and 17 are nearsighted.

The most striking numbers emerge when researchers look not at the country as a whole, but at individual urban populations.

In a 2017 study of 1,478 schoolchildren at two schools in Tokyo, myopia was found in 76.5 percent of children ages 6 to 11. Among those ages 12 to 14, the figure reached 94.9 percent.

That does not mean that 95 percent of all Japanese teenagers are nearsighted: the study was limited to two schools in Tokyo. But it demonstrates how widespread myopia can become in an urban environment.

And that raises an uncomfortable question:

Did the digitalization of education make Japanese children nearsighted?

The scientific answer is considerably more complicated.

BY THE NUMBERS: Japan’s Myopia Problem

≈5.5 million — estimated number of Japanese children ages 5–17 with myopia.

21% — proportion of first-grade elementary school students with uncorrected visual acuity below 1.0.

≈58–65% — the corresponding figure among third-year middle-school students: about 58 percent of boys and 65 percent of girls.

94.9% — prevalence of myopia among 12–14-year-olds in a 2017 study of two Tokyo schools.

≈22% of sixth-graders and ≈29% of third-year middle-school students — the proportion reporting four or more hours of weekday video viewing and social-media use in recent national MEXT data.

First, the Distance Disappears

Myopia is not simply a condition in which a child needs glasses.

In a nearsighted eye, images of distant objects are focused in front of the retina rather than directly on it. In many cases, the underlying problem is that the eyeball has become too long.

That distinction matters.

Glasses can correct the image reaching the retina. They do not shorten the eye itself.

With high myopia, excessive elongation of the eyeball increases the risk of damage to the retina, choroid and other structures of the eye. One of the most serious complications is myopic maculopathy, a disease of the central retina responsible for the sharpest part of our vision.

That is why ophthalmologists view childhood myopia differently from the simple need for a new pair of glasses.

The earlier myopia begins—and the faster it progresses—the longer the eye is exposed to the structural consequences of excessive elongation.

Long-term studies of Japanese adults already offer a glimpse of what may lie ahead.

In the Hisayama Study, the prevalence of myopia among people over 40 increased from roughly 38 percent to 46 percent between 2005 and 2017. The proportion with high myopia rose from about 6 percent to 10 percent, while the prevalence of myopic maculopathy increased from 1.6 percent to 3.6 percent.

What happens to children’s eyes today could therefore shape the burden on ophthalmology decades from now.

The Tablet Enters the Classroom

In 2019, Japan launched the GIGA School Concept, an ambitious national program to digitize education.

The idea was straightforward: provide students with individual digital devices and high-speed internet, turning computers from occasional classroom equipment into everyday educational tools.

By the end of fiscal year 2023, Japan had essentially achieved the goal of providing one device for every student in compulsory education.

Then came the pandemic.

Schools closed, children studied from home, and digital devices became even more central to education. The boundary between schoolwork and screen time began to disappear.

At first glance, the causal chain seems obvious: more tablets → more screen time → more myopia.

But this is precisely where researchers urge caution.

Japanese children were already becoming highly myopic long before GIGA School.

The Epidemic Predates the Tablet

The Tokyo study that found myopia in nearly 95 percent of 12–14-year-olds was conducted in 2017.

That was before the pandemic. Before the full nationwide rollout of GIGA School.

The finding therefore cannot be used to argue that the digitalization of Japanese schools caused the country’s myopia epidemic.

More broadly, myopia develops through the interaction of multiple factors.

Genetic predisposition matters. So does lifestyle.

One of the most consistently supported risk factors is insufficient time spent outdoors. Studies from several countries have found that greater exposure to outdoor time is associated with a lower risk of developing myopia.

Then there is another factor: near work.

This is where digital devices become particularly interesting.

Not because screens possess some unique property that makes eyes myopic, but because smartphones and tablets can change how long—and how close—we look at things.

BY THE NUMBERS: What Happens at 20 Centimeters?

To focus on an object 30 centimeters away, the eye requires roughly 3.3 diopters of accommodation.

At 20 centimeters, it requires about 5 diopters.

Moving an object from 30 to 20 centimeters therefore increases the required accommodative effort by roughly 50 percent.

That does not mean that this accommodative demand automatically causes myopia.

It illustrates a simpler optical fact:

the closer the object, the greater the focusing demand.

The Screen Is Not the Only Suspect

This distinction is crucial.

A child reading a paper book at 20 centimeters is creating essentially the same optical demand as a child looking at a smartphone at the same distance.

The scientific question, therefore, is not simply:

Are screens harmful?

A more useful question is:

How has the total amount of near work changed—and what has happened to the amount of time children spend outdoors?

Digital devices can substantially increase near-work exposure. They allow children to read, write, play, watch videos and communicate for hours while maintaining essentially the same viewing distance.

That makes the digital environment a potentially important part of the problem.

But potentially important is not the same as proven causal.

There is currently no sound basis for claiming that GIGA School itself caused Japan’s myopia epidemic.

Another Warning Sign: When the Eyes Turn Inward

The digital story may have another dimension.

In recent years, Japanese ophthalmologists have paid increasing attention to acute acquired comitant esotropia, a form of strabismus in which one or both eyes turn inward and double vision can occur.

Japanese studies have found an association between the condition and prolonged use of portable digital devices.

In one multicenter Japanese study of patients ages 5 to 35, average weekday use of such devices was about 159 minutes among children ages 5–12, 210 minutes among adolescents ages 13–18, and 267 minutes among young adults.

Individual Japanese clinical reports have also described teenagers spending more than four hours a day on smartphones.

There is reason to suspect that prolonged work at very close range may contribute to the development of the disorder.

But again, the science does not yet allow a simple conclusion that smartphones are the cause.

Recent reviews by Japanese ophthalmologists point to an association but emphasize that the evidence remains insufficient to establish a population-level causal effect.

That distinction matters.

A signal detected by researchers is not yet a cause demonstrated by science.

Japan Starts Measuring the Eye Itself

Meanwhile, Japan is trying to collect a kind of data it did not have before.

MEXT—the Ministry of Education, Culture, Sports, Science and Technology—is conducting a dedicated national study of childhood myopia. Researchers are no longer satisfied with knowing whether a child can read the last line on an eye chart.

They are measuring refractive error and axial length—the distance from the front of the eye to the retina.

That is a significant methodological shift.

A conventional vision test asks: “How well can this child see?”

Measuring axial length asks a different question: “What is happening to the eye itself?”

The first phase of the study included approximately 8,600 students at 29 schools.

Researchers also collected information about the children’s lifestyles, including habits involving digital devices.

The result is a much richer picture: refractive error, the physical dimensions of the eye, daily habits and environmental factors can now be examined together.

That makes it possible to study not only how common myopia is, but also which factors are associated with its development and progression.

BY THE NUMBERS: From the Eye Chart to the Eyeball

Traditional vision screening measures the functional result.

Modern myopia research attempts to measure the underlying mechanism.

Visual acuity → how well a child can see.

Refraction → how the eye’s optical system focuses an image.

Axial length → how long the eyeball has become.

That last measurement is particularly important when researchers are assessing the progression of myopia.

From Glasses to Prevention

Japan is not starting from scratch.

A range of approaches is already used to slow the progression of myopia, including orthokeratology—overnight contact lenses that temporarily reshape the cornea—and low-dose atropine.

But treating an individual child and preventing a population-wide problem are very different tasks.

If myopia is affecting millions of children, the questions extend beyond the ophthalmologist’s office.

How long should a child spend doing near work?

How much time should children spend outdoors?

How should a digital lesson be structured?

How often should students take breaks?

How far should a screen be from the eyes?

And how can digital education be designed so that it does not turn a child’s entire day into hours of uninterrupted near work?

There is no single universal answer to these questions yet.

But the questions themselves reveal how fundamentally the problem has changed.

The Government Changes Its Language

In 2026, prevention of childhood myopia received direct recognition in Japan’s Basic Policy, a key document outlining the government’s economic and fiscal priorities.

That represents an important institutional shift.

Myopia is no longer viewed solely as a private medical problem to be managed by an ophthalmologist and a family.

It is becoming an issue of preventive public policy.

At the same time, national monitoring continues, with the goal of determining which factors are actually associated with structural changes in children’s eyes.

Japan has effectively become a natural laboratory.

The country was among the first to confront large-scale digitalization of school education, while also having a long history of high myopia prevalence and an increasingly sophisticated system for diagnosing and managing the condition.

That combination gives researchers a rare opportunity to observe what happens when childhood itself changes.

WHAT WE KNOW

Myopia is widespread in Japan. Particularly high rates have been documented in some urban school populations.

Myopia has multiple contributing factors. Genetics, near work and insufficient outdoor time are among the most important areas of research.

Digital devices have increased children’s exposure to near work. GIGA School has made tablets and computers a routine part of Japanese education.

Screen use is substantial. National MEXT data show that a significant proportion of students spend four or more hours on weekday video viewing and social-media use.

High myopia can have long-term consequences. It increases the risk of pathological changes in the retina, including myopic maculopathy.

Japan is expanding national monitoring. MEXT is measuring refraction and axial length in schoolchildren while collecting information about their lifestyles.

WHAT WE DON’T KNOW YET

Did GIGA School cause the rise in myopia? There is not enough evidence to make that claim. High rates of myopia were documented in Japan before school tablets became ubiquitous.

How much of the risk comes specifically from screens? It remains unclear how much is attributable to the screen itself and how much to duration of near work, viewing distance and overall lifestyle.

What is the population-level effect of smartphones on acute acquired esotropia? Associations have been observed, but the causal mechanism and magnitude of the effect remain under investigation.

Which combination of preventive measures works best? More outdoor time, better management of near work, regular breaks and medical approaches to myopia control may all have roles, but their relative contributions are still being studied.

Perhaps the Problem Isn’t the Tablet

The simplest explanation is also the weakest.

It is easy to blame the tablet. It is easy to declare the smartphone the new enemy of children’s eyesight. It is even possible to imagine removing screens from classrooms altogether.

But Japan’s data tell a more complicated story.

The country’s myopia epidemic began before GIGA School. Digitalization did not create the problem from scratch. It entered an environment in which children were already spending substantial amounts of time reading and doing near work, spending too little time outdoors, and carrying varying degrees of genetic susceptibility to myopia.

But the digital age has changed the scale.

Today, the same child can spend a substantial portion of the day focusing on objects just a few inches from the face. That is a very different visual environment from the one in which the human eye evolved.

Japan’s experience does not yet tell us that tablets “damage” children’s eyes.

It points to a more interesting question:

What happens to the human eye when much of childhood is spent looking at things up close?

The answer is gradually emerging—in measurements of eyeball length, in myopia statistics, in studies of strabismus and in millions of pairs of young eyes.

And perhaps the next stage of digital education will not be about abandoning screens.

It will be about learning how to build a digital childhood around the limits of the human eye.