Daily Dose / Aug 22, 2026 / Myopia

The Nearsighted
Century

Short-sightedness used to be a footnote of human variation. In three generations it has become the most common eye condition on Earth — and the cause is less about genes than about where children spend their daylight hours.

4.76BILLION

People projected to be myopic by 2050 — 49.8% of the world. In 2000 it was 1.41 billion, or 22.9%. Modeled projection from 145 studies of 2.1 million people. (Holden et al., Ophthalmology, 2016)

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FOCUS

THEDAY

LIGHTFALLS

TOOSHORTNOWX

A myopic eye is not a weak eye — it is a long eye. High myopia begins at −6.00 D, roughly an eyeball 26 mm or longer against a typical 23–24 mm.

01 — The curve

Half the planet, in one lifetime

Global myopia prevalence roughly doubles between 2000 and 2050. High myopia — the sight-threatening kind — grows almost four times faster in relative terms.

Myopia (any) High myopia (≤ −5.00 D)

Percent of world population. 2020–2050 values are modeled projections, not measurements. Counts: 1,406 M (2000) → 2,620 M (2020) → 4,758 M (2050); high myopia 163 M → 399 M → 938 M. Source: Holden et al., Ophthalmology 123(5), 2016.

02 — The spectrum

An eye grows toward the light it doesn't get

Bright light drives retinal dopamine release, which brakes the eyeball's elongation. The relevant variable is illuminance — and indoors, humans live two orders of magnitude below the outdoor world.

≈1,000 lux — the "outdoor" threshold

162

Under a
dense canopy

179

Indoors
(median, all rooms)

800

Outdoors,
cloudy day

1,920

Outdoors,
sunny day

9,300

Open
playground

≈100,000

Direct
summer sun

Median illuminance in lux; the strip is a log-spaced scale, one hue light→dark. Measured values from Bhandary et al., PLoS ONE, 2021 (indoor median 179 lux, IQR 50–333; open playground 9,300 lux, range 4,100–16,825). The 100,000-lux figure for direct summer sun is a standard reference approximation, not a measurement from that study. A 2022 randomized trial with wearable light sensors found that roughly 300,000 lux·min of accumulated daily exposure was associated with about a 20% lower risk of myopia onset (Wu et al., Ophthalmology, 2022).

03 — The geography

It started in the classrooms of East Asia

Every world region is projected to climb. The regions that industrialized childhood schooling first got there first — and the rest of the world is following the same curve, a few decades behind.

2000 (measured baseline) 2050 (projected)

Asia-Pacific, high inc.

66.4%

East Asia

65.3%

Southeast Asia

62.0%

North America, high inc.

58.4%

Western Europe

56.2%

South Asia

53.0%

Southern Africa

30.2%

East Africa

22.7%

Full-height bar = projected 2050 prevalence; the low bar beneath it = the 2000 baseline. Source: Holden et al., Ophthalmology, 2016, Table 1. 2050 values are modeled.

96.5%

Seoul, 2010

Myopia in 19-year-old male conscripts from Seoul — with 21.6% already in the high-myopia range. (Jung et al., IOVS, 2012)

86.1%

Taiwan, 2010–11

Myopia among male military conscripts aged 18–24. In 1983, 74% of Taiwanese 18-year-olds were myopic; by 2004, 84%.

41.6%

United States, 1999–2004

Up from 25.0% in 1971–72 among ages 12–54 (Vitale et al., 2009). A 2025 reappraisal argues much of that rise reflects myopia that develops after age 18, not only a generational shift.

04 — The natural experiment

What happened when the children stayed inside

In 2020, home confinement in Feicheng, China removed outdoor time from an entire cohort at once. School photoscreenings of 123,535 children had been running since 2015 — so the before-and-after was already instrumented.

Highest prior year, 2015–19 2020

Myopia prevalence by age in 2020 versus the highest value recorded in the preceding five years. Six-year-olds went from 5.7% to 21.5% — a near-quadrupling in one year. Mean refraction shifted about −0.30 D in the 6–8 age band; older children barely moved. Source: Wang et al., JAMA Ophthalmology 139(3), 2021.

05 — The interventions

Daylight is the cheapest treatment we have

Myopia is one of the few global health trends with a demonstrated, low-tech brake — and it has already been pulled at national scale.

Atropine 0.05%, 1 yr

67%

DIMS spectacles, 2 yr

59%

Dual-focus lenses, 3 yr

59%

+40 min outdoors, 3 yr

23%

Reduction versus control. The first three are slowing of progression in children who are already myopic; the last is reduction in the incidence of becoming myopic at all — different outcomes, not directly comparable, but the outdoor arm is free and has no side effects. Sources: Frontiers in Public Health review (2023); Lam et al., BJO, 2020; Chamberlain et al., Optom Vis Sci, 2019; He et al., JAMA, 2015.

39.5% → 30.4%

Guangzhou, 2010–2013

In a cluster-randomized trial of first-graders, adding one 40-minute outdoor class period per school day cut the three-year cumulative incidence of myopia from 39.5% to 30.4%. (He et al., JAMA, 2015)

49.4% → 46.1%

Taiwan, 2012–2015

After the national Tian-Tian 120 policy pushed schoolchildren outdoors for 120 minutes a day, the prevalence of reduced visual acuity fell for the first time in a decade — reversing a rise from 34.8% (2001) to 50.0% (2011) across 1.2–1.9 million primary pupils. (Wu et al., Ophthalmology, 2020)

06 — The stakes

Every diopter is a compounding risk

Myopia is treated as an inconvenience corrected by a $20 lens. In its severe form it is a structural disease of the retina — and the risk does not rise gently.

+67%

Per diopter

Each additional diopter of myopia is associated with a 67% higher prevalence of myopic maculopathy. Slowing a child by just 1 D cuts that lifetime risk by roughly 40%. (Bullimore & Brennan, Optom Vis Sci, 2019; pooled data on ~21,000 people)

$244BN

Lost productivity, 2015

Global potential productivity lost to vision impairment from uncorrected myopia, plus $6 bn from myopic macular degeneration. 538 million people were affected. (Naidoo et al., Ophthalmology, 2019)

2.2BN

Vision impairment, worldwide

At least 2.2 billion people live with near or distance vision impairment; for at least 1 billion it was preventable or is simply unaddressed. Clearing the refractive-error and cataract backlog is costed at $14.3 bn. (WHO World Report on Vision, 2019)

What to do with this

Two hours of daylight, and a number to ask for

01Get children outside for about two hours a day. The protective ingredient is light intensity, not exercise — a shaded playground still delivers ten times the illuminance of a bright living room. Before age 9 matters most.
02Screen early, then track axial length, not just the prescription. Eye elongation of 0.10 mm a year or more in a child is the signal clinicians watch; it is measured painlessly in seconds.
03Ask whether myopia control is on the table. Low-dose atropine, dual-focus contact lenses and defocus spectacles all have randomized evidence. Standard single-vision glasses correct the blur but do nothing about the growth.
04Remember the other half of the problem. Hundreds of millions of people who are already myopic simply do not own the glasses that would fix it — the single most cost-effective intervention in the whole story.

Sources & notes

Holden BA, Fricke TR, Wilson DA, et al. Global Prevalence of Myopia and High Myopia and Temporal Trends from 2000 through 2050. Ophthalmology 123(5):1036–1042, 2016. All 2020–2050 figures here are modeled projections, not observations.
Bhandary SK, et al. Ambient light level varies with different locations and environmental conditions: potential to impact myopia. PLoS ONE, 2021. (Illuminance medians.)
Wu PC, et al. Time Outdoors in Reducing Myopia: a school-based cluster randomized trial with objective monitoring of outdoor time and light intensity. Ophthalmology, 2022.
He M, Xiang F, Zeng Y, et al. Effect of Time Spent Outdoors at School on the Development of Myopia Among Children in China: A Randomized Clinical Trial. JAMA 314(11):1142–1148, 2015.
Wu PC, et al. Increased Time Outdoors Is Followed by Reversal of the Long-Term Trend to Reduced Visual Acuity in Taiwan Primary School Students. Ophthalmology 127(11), 2020.
Wang J, Li Y, Musch DC, et al. Progression of Myopia in School-Aged Children After COVID-19 Home Confinement. JAMA Ophthalmology 139(3):293–300, 2021. (123,535 children, Feicheng, China.)
Vitale S, Sperduto RD, Ferris FL. Increased Prevalence of Myopia in the United States between 1971–1972 and 1999–2004. Archives of Ophthalmology 127(12):1632–1639, 2009. See also the 2025 reappraisal in Ophthalmology Science, which attributes a large share of the rise to adult-onset myopia.
Jung SK, et al. Prevalence of myopia and its association with body stature and educational level in 19-year-old male conscripts in Seoul, South Korea. Investigative Ophthalmology & Visual Science, 2012. Taiwan and Singapore conscript figures as reviewed in the epidemiology-of-pathologic-myopia literature (Asia-Pacific Journal of Ophthalmology).
Bullimore MA, Brennan NA. Myopia Control: Why Each Diopter Matters. Optometry and Vision Science 96(6):463–465, 2019.
Naidoo KS, Fricke TR, Frick KD, et al. Potential Lost Productivity Resulting from the Global Burden of Myopia. Ophthalmology 126(3):338–346, 2019. Economic figures are modeled estimates in 2015 US dollars.
World Health Organization. World Report on Vision, 2019.
Lam CSY, et al. Defocus Incorporated Multiple Segments (DIMS) spectacle lenses slow myopia progression: a 2-year randomised clinical trial. British Journal of Ophthalmology 104(3), 2020. Chamberlain P, et al. A 3-year randomized clinical trial of MiSight lenses for myopia control. Optometry and Vision Science, 2019. Atropine efficacy range from a systematic review of 12 RCTs, Frontiers in Public Health, 2023.
Note on definitions: "myopia" here is ≤ −0.50 D spherical equivalent and "high myopia" ≤ −5.00 D, following Holden et al.; some studies cited use ≤ −6.00 D for high myopia. Axial-length thresholds (23–24 mm typical, ≥26 mm high myopia) are clinical conventions.