Childhood Myopia (Nearsightedness): A Complete Guide to the Global Epidemic, Its Risks, and Proven Treatments

Table of Contents

• Key Points
• Introduction: Why This Research Matters
• Epidemiology: A Worldwide Epidemic
• What Causes Myopia? The Science Behind the Condition
• Clinical Presentation and Complications
• How Myopia Is Diagnosed in Children
• The Genetics of Myopia
• Syndromic Myopia: When Myopia Signals a Broader Condition
• Myopia Control: Strategies to Slow Progression
  • Outdoor Time
  • Special Glasses: Bifocal, Progressive, and Defocus Lenses
  • Defocus Contact Lenses
  • Orthokeratology (Night-Time Corneal Molding)
  • Atropine Eye Drops
  • Scleral Reinforcement Surgery
  • Frequently Asked Questions

  Key Points

  • About 23% of the world was myopic in 2000; projections suggest nearly 50% by 2050.
  • High myopia can cause retinal detachment, glaucoma, early cataracts, and abnormal vessel growth.
  • In children, progression is at least -0.5 diopters per year; early detection is essential.
  • Outdoor time, defocus lenses, orthokeratology, and low-dose atropine can slow progression by about 50%.
  • Some cases of myopia are syndromic, like Stickler or Marfan syndrome, needing systemic workup.
• Clinical Implications: What These Findings Mean for Patients
• Limitations of This Review
• Recommendations for Parents and Patients
• Source Information

Introduction: Why This Research Matters

Myopia — commonly called nearsightedness — is a refractive error of the eye that has become a worldwide public health concern. The condition gets its name from the Greek words meaning "I close the eye," which describes the squinting behavior people with myopia often use to see distant objects more clearly. Far from being a simple inconvenience, myopia is now described by experts as a "global myopia epidemic."

The word "myopia" describes an eye that is too long from front to back (increased axial length). Instead of focusing light precisely on the retina at the back of the eye, the image forms in front of the retina, making distant objects look blurry. But myopia is not just about blurry distance vision. It also carries the risk of potentially blinding complications later in life, including retinal detachment, abnormal blood vessel growth in the retina (retinal neovessels), early cataracts, and glaucoma.

Among children younger than 6 years old, about 20% have visual anomalies. The most common are refractive errors like myopia, followed by strabismus (crossed or misaligned eyes) and amblyopia (lazy eye). This makes early detection critically important.

The good news, as this review explains, is that progressive myopia can now be slowed. The most promising strategies include spending more time outdoors, wearing special defocus-correcting glasses or contact lenses, orthokeratology (night-time corneal reshaping), and treatment with low-dose atropine eye drops. The goal is to limit excessive eyeball growth and reduce the risk of sight-threatening complications in adulthood.

Epidemiology: A Worldwide Epidemic

The scale of the myopia problem is staggering. In the year 2000, a child somewhere in the world became blind every single minute — that equals 1.4 million blind children globally. Myopia has become the most widespread visual disorder on the planet, and its prevalence is rising sharply.

The rise was first noticed in Asian countries, but it has now spread worldwide. According to projections by Holden and colleagues, nearly 50% of the world's population will be myopic by 2050. In some Asian countries, such as Singapore and Taiwan, myopia already affects up to 85% to 90% of young adults. In the United States and Europe, between 25% and 50% of older adults are myopic.

Let's look at the raw numbers from the Holden study:

• In 2000: approximately 1,406 million people (1.4 billion) were myopic — that's 23% of the world population. Of these, about 163 million had high myopia (requiring a correction stronger than −5 diopters [D]), representing 2.7% of the population.
• Projected for 2050: approximately 4,758 million people (4.8 billion) will be myopic — 49.8% of the world population. High myopia is expected to affect 938 million people, or 9.8% of the population.

This increase in high myopia matters because it is directly linked to serious eye complications. These complications are the main causes of low vision and blindness associated with myopia. In Western countries, where populations are aging, myopia could also reduce life expectancy and increase early loss of independence in older adults.

The economic burden is enormous. The global socio-economic cost of myopia has been estimated at 268 billion US dollars per year. This reinforces why myopia must be treated as a global public health priority, not just an optical inconvenience.

What Causes Myopia? The Science Behind the Condition

Myopia develops through a complex interaction between genetic predisposition and environmental exposure. During visual development, several factors can push the eye toward becoming myopic. The genetics are multifactorial, meaning many different genes contribute, and environmental triggers determine whether those genetic tendencies are expressed.

One key concept is visual deprivation. When the eye experiences a certain type of blurry vision — for example, from uncorrected myopia — it responds by growing longer. This process, called myopization, is the eye's attempt to compensate, but it actually makes the myopia worse. In a myopic eye, the focal point for central vision (at the macula) falls in front of the retina because the eyeball is too long. Meanwhile, in the peripheral retina, the focal point falls behind the retina — a situation called peripheral hypermetropic defocus — which further stimulates axial elongation.

Another important environmental factor is light exposure. Studies suggest that light stimulation, which varies by wavelength, triggers the release of dopamine in the retina. Dopamine and dopaminergic agonists appear to inhibit the excessive elongation of the eye. This may explain why spending time outdoors in bright light protects against myopia.

Near work also plays a role. Studies show that students have a higher prevalence of myopia, and experimental research has found that animals fitted with concave lenses — which simulate near work — develop myopia. It seems likely that the increase in near-vision activities in modern life has contributed to the global rise in myopia.

There is an ongoing controversy about the type of light children are exposed to, particularly blue light versus violet light. Research in primates has shown that defocus at the peripheral retina induces axial myopia, while foveal (central) vision does not influence the process of emmetropization — the natural growth process that normally balances the eye's focusing power with its length, which begins at birth. Recent electrophysiological studies in humans have also shown that the retina itself contributes to decoding defocused images through changes in the signaling of retinal ganglion cells, the nerve cells that carry visual information from the retina to the brain.

Clinical Presentation and Complications

Beyond needing glasses, myopia can lead to severe complications — some of which can cause blindness. This is why preventing myopia progression in childhood is so important: it prevents visual disability in adulthood.

In children, the onset of myopia is defined as a refraction greater than −0.5 diopters combined with an increase in axial length. Myopia is considered progressive when it increases by −0.5 diopters per year or more. Identifying this early is the key to starting treatment.

The main complications of myopia, which become more frequent as the myopia becomes more severe, include:

• Retinal detachment — the retina peels away from its underlying support tissue
• Myopic chorioretinal degeneration — thinning and deterioration of the retina and the choroid layer beneath it
• Subretinal neovascular complications — abnormal blood vessels growing under the retina
• Early-onset cataracts — clouding of the eye's natural lens at a younger age than usual
• Glaucoma — damage to the optic nerve, often linked to elevated eye pressure

These complications are a direct consequence of the eyeball becoming too long. The stretched tissues of the eye become fragile and prone to damage.

The review also warns that under-correction should never be recommended. Data from prospective clinical trials suggest that under-correcting myopia either increases the rate of progression or has no effect at all. Children should always receive their full, accurate prescription.

Doctors must also rule out congenital glaucoma when examining a myopic child, especially when the myopia is unilateral (affecting only one eye), because glaucoma initially causes the eyeball to elongate alongside rising intraocular pressure.

How Myopia Is Diagnosed in Children

Children's vision develops in stages, and screening follows the recommendations of the French health record (carnet de santé). If any anomaly is found, a complete ophthalmologic examination is performed.

From the age at which a child can speak, visual acuity can be measured for both near and far distances using directional tests, drawings, and/or letters. If needed, an object-matching method is used. This helps detect a possible refractive error.

A full eye exam with refraction under cycloplegia is essential. Cycloplegia involves using eye drops that temporarily paralyze the internal and external muscles of the eye (the focusing muscles). This is the only reliable way to measure a child's true refractive error, because it prevents the child's natural focusing ability from masking the real prescription.

Optical biometry — a painless measurement of the eye's axial length — is also important for the initial assessment and for tracking myopia progression over time. In older children, measuring visual acuity is the cornerstone for detecting refractive errors such as myopia. Refractive screening is becoming increasingly important given the rising prevalence of myopia in Europe. If certain conditions are suspected, electrophysiological tests can complete the workup and help diagnose retinal dystrophies (inherited retinal diseases) or problems with the transmission of visual signals through the visual pathways.

The Genetics of Myopia

Myopia has multiple causes that are still incompletely understood, but the genetic component is well proven. In families with high myopia, specific genetic regions have been identified, including 18p11.31, 12q21-31, and 7q36. Some populations, particularly Asian populations, naturally have eyes that are more prone to myopia.

Large-scale genetic studies called GWAS (genome-wide association studies) have attempted to identify the specific genes linked to myopia risk. To date, nearly 200 genes appear to be associated with myopia, either individually or in combination. However, genetics alone does not tell the whole story — the interaction with environmental factors like near work and outdoor time is what ultimately determines whether a child becomes myopic.

Syndromic Myopia: When Myopia Signals a Broader Condition

In some children, myopia is not an isolated finding but a sign of an underlying genetic syndrome. When a child has high myopia or rapidly progressing myopia, a thorough pediatric and systemic workup is crucial to identify associated pathologies and reach a syndromic diagnosis. This includes careful clinical phenotyping (documenting all physical features) and, when indicated, targeted genetic testing.

Many of these syndromes have a genetic (Mendelian) inheritance pattern with identified responsible genes. Flitcroft and colleagues analyzed the OMIM (Online Mendelian Inheritance in Man) database to catalog the genes involved in syndromic forms of myopia and the associated signaling pathways.

The table below summarizes the most common syndromic myopias, their clinical features, and the genes involved. This is not exhaustive, but it serves as a diagnostic aid when myopia is found alongside other clinical signs.