Definition and epidemiology
Myopia (nearsightedness) is a refractive error in which parallel light rays entering the relaxed eye converge at a focal point anterior to the retina, producing blurred images of distant objects while near objects remain in focus.
- Prevalence is rising globally, especially in East Asia, where some urban adolescent populations show rates exceeding 80-90%.
- In the US and Europe, prevalence in young adults is roughly 25-40% and increasing over recent decades.
- Onset is most common between ages 6 and 14, with progression typically continuing until the late teens or early twenties.
- High myopia (generally defined as worse than -6.00 diopters or axial length greater than 26 mm) carries increased risk of sight-threatening complications and is more common in East Asian populations.
- Myopia = light focuses in front of the retina; corrected with minus (concave) lenses.
- Axial elongation of the globe is the principal mechanism in progressive and high myopia.
- Cycloplegic refraction is the gold standard for accurate diagnosis, especially in children.
- Increased outdoor time is an evidence-based measure to reduce myopia onset and progression in children.
- Low-dose atropine and orthokeratology are first-line options for slowing pediatric myopia progression.
- High myopia (>-6.00 D or axial length >26 mm) raises risk of retinal detachment and myopic maculopathy.
- Pseudomyopia (accommodative spasm) mimics true myopia but resolves with cycloplegic refraction.
- Refractive surgery is reserved for adults with stable refraction, not for children.
Etiology and risk factors
Myopia arises from a combination of genetic predisposition and environmental factors, with the latter increasingly implicated in the recent global rise in prevalence.
Genetic factors
- Strong heritability; risk increases substantially with one or two myopic parents.
- Numerous susceptibility genes identified, but inheritance is polygenic and complex.
Environmental and behavioral factors
- Near work: prolonged reading, near-screen use, and intensive early education are associated with higher risk.
- Reduced outdoor time: strongly and consistently linked to myopia onset and progression in children; thought to be mediated by light exposure and dopamine release in the retina.
- Urban residence and higher socioeconomic/educational demands correlate with higher prevalence.
Other associations
- Prematurity and low birth weight.
- Certain connective tissue disorders (e.g., Marfan syndrome, Stickler syndrome) and ocular conditions (e.g., congenital cataract, retinopathy of prematurity) are associated with myopia, particularly high or early-onset forms.
Pathophysiology
Myopia occurs when the eye's optical power is too strong for its axial length, or the axial length is too long for its optical power, so the image plane falls in front of the retina rather than on it.
- Axial myopia (most common): elongation of the globe, particularly the vitreous chamber, is the primary mechanism, especially in progressive and high myopia.
- Refractive (curvature) myopia: excessive curvature of the cornea or lens, or increased lens refractive index, without significant axial elongation.
- Animal and human studies implicate scleral remodeling driven by signals from the retina and choroid; defocus of peripheral retinal images is thought to promote axial elongation.
- Reduced outdoor light exposure is hypothesized to lower retinal dopamine release, a factor that normally inhibits axial elongation, contributing to the near-work and outdoor-time associations.
- Progressive axial elongation thins and stretches the retina and choroid, which underlies the pathologic complications seen in high myopia (e.g., retinal detachment, myopic maculopathy).
Clinical features
- Blurred distance vision (difficulty reading signs, whiteboards, or recognizing faces from afar) while near vision (reading, phone use) is typically unaffected.
- Squinting to improve clarity through pinhole effect.
- Headaches or eye strain, particularly with uncorrected moderate-to-high myopia.
- Children may hold books close, sit near the front of the classroom, or show declining academic performance attributed to poor board visibility.
- In high myopia: floaters, flashes of light, or peripheral visual field changes may indicate complications such as posterior vitreous detachment or retinal tear/detachment and warrant urgent evaluation.
- Progressive myopia in children is often noted by parents or detected on school vision screening.
Diagnosis
Diagnosis is clinical, based on standardized refraction testing.
- Visual acuity testing: Snellen or equivalent chart; distance acuity is reduced, near acuity preserved.
- Cycloplegic refraction: the gold standard, especially in children, to eliminate accommodative spasm and obtain an accurate measurement of refractive error; cycloplegic agents (e.g., cyclopentolate) temporarily paralyze accommodation.
- Autorefraction and retinoscopy are used as objective adjuncts.
- Axial length measurement (optical biometry) is increasingly used, particularly to monitor progression in children and assess risk of high myopia.
- Dilated fundus examination is important in moderate-to-high myopia to screen for peripheral retinal thinning, lattice degeneration, or early myopic maculopathy.
- Refractive error is expressed in diopters (D) with a minus sign (e.g., -3.00 D); severity is commonly classified as:
| Category | Spherical equivalent |
|---|---|
| Low myopia | up to -3.00 D |
| Moderate myopia | -3.00 to -6.00 D |
| High myopia | worse than -6.00 D |
Differential diagnosis
- Hyperopia: light focuses behind the retina; corrected with plus (convex) lenses; near vision is typically more affected.
- Astigmatism: irregular corneal or lens curvature causing distorted vision at all distances; often coexists with myopia.
- Presbyopia: age-related loss of accommodation affecting near vision in adults; distinct mechanism from myopia.
- Pseudomyopia (accommodative spasm): transient myopic shift due to ciliary muscle spasm, often from excessive near work; resolves with cycloplegic refraction, which distinguishes it from true myopia.
- Cataract: can cause an index myopic shift (lens-induced myopia) in adults, usually with other lens opacity findings.
- Keratoconus: progressive corneal thinning causing irregular astigmatism and myopic shift, often with distinctive topography findings.
Management
Management goals differ for correcting current refractive error versus slowing progression in children at risk of high myopia.
Correction of refractive error
- Eyeglasses with concave (minus) lenses: first-line, safest option for all ages.
- Contact lenses: alternative for suitable candidates, including soft lenses and rigid gas-permeable lenses.
- Refractive surgery (e.g., LASIK, PRK, implantable lenses): option for stable refractive error in adults, not used in children due to ongoing eye growth.
Myopia control in children (progression)
International guidelines (American Academy of Ophthalmology, International Myopia Institute, and others) now recommend considering progression-control interventions for children with progressive myopia, given rising global prevalence and complication risk:
- Low-dose atropine eye drops: reduce progression rate; optimal concentration still under study, with higher concentrations more effective but with more rebound and side effects (photophobia, blurred near vision).
- Orthokeratology (ortho-K): overnight rigid lenses that reshape the cornea; evidence supports modest reduction in axial elongation.
- Specially designed spectacle lenses (e.g., defocus incorporated multiple segments, peripheral defocus designs) and multifocal soft contact lenses: reduce progression compared with standard single-vision correction.
- Increased outdoor time (at least 2 hours/day where feasible): evidence-based, low-risk behavioral measure recommended as adjunct for all children, regardless of other interventions.
- Regular monitoring of axial length and refraction every 6-12 months in children undergoing myopia control.
Monitoring for complications
- Annual or biannual dilated fundus exams in high myopia to screen for retinal breaks, lattice degeneration, and myopic maculopathy.
- Patient education on urgent symptoms (flashes, floaters, curtain-like vision loss) warranting same-day ophthalmologic evaluation.
Complications and prognosis
Most low-to-moderate myopia has an excellent prognosis with simple optical correction and no significant risk of vision-threatening disease. Progression typically slows and stabilizes by the late teens to early twenties.
High myopia carries increased lifetime risk of:
- Retinal detachment (due to peripheral retinal thinning and vitreous changes).
- Myopic maculopathy (chorioretinal atrophy, lacquer cracks, myopic choroidal neovascularization), a leading cause of irreversible vision loss in high myopes.
- Glaucoma: increased risk, independent of intraocular pressure elevation in some studies.
- Early cataract formation, including nuclear sclerotic cataract.
- Posterior staphyloma: localized outpouching of the posterior sclera seen in pathologic myopia.
Early identification and progression control in childhood, combined with regular surveillance in adulthood, reduce the lifetime burden of these complications.
MYOPIA progression risk factors — "NEAR": Near work, Ethnicity (East Asian), Ancestry/family history, Reduced outdoor time.
Practice questions
1. A 9-year-old boy is brought by his parents because he has been squinting to see the classroom whiteboard and sitting closer to the television. His father wore glasses from a young age. On examination, visual acuity improves to 20/20 with a -2.50 D lens in each eye. Which of the following best explains this child's condition?
2. A 24-year-old woman with high myopia (-9.00 D) presents with sudden onset of flashes of light and a curtain-like shadow in the peripheral vision of her left eye. Which complication of high myopia is most likely occurring?
3. A 10-year-old girl has progressive myopia, increasing from -1.00 D to -3.00 D over two years despite correction with single-vision glasses. Her parents ask about options to slow further progression. Which of the following interventions has the best evidence for reducing myopia progression in children?
Frequently asked questions
What causes myopia?
Myopia is caused mainly by an eyeball that is too long relative to its focusing power, so images form in front of the retina. Genetics play a major role, with risk rising sharply if one or both parents are myopic. Environmental factors, especially extensive near work and reduced outdoor time during childhood, strongly contribute to onset and progression.
What are the first symptoms of myopia?
The first symptom is usually blurred vision for distant objects, such as difficulty reading a whiteboard or road signs, while near vision stays clear. Children may squint, sit closer to screens or the front of a classroom, or complain of headaches and eye strain. Parents often notice these behaviors before a formal diagnosis is made.
How is myopia diagnosed?
Myopia is diagnosed through a standard eye exam measuring visual acuity, followed by refraction testing to quantify the degree of nearsightedness. In children, cycloplegic refraction (using eye drops that temporarily paralyze focusing muscles) is the gold standard to avoid overestimating the error. A dilated fundus exam is added for moderate-to-high myopia to check retinal health.
Is myopia curable?
Myopia is not curable in the sense of reversing eye growth, but it is very effectively correctable with glasses, contact lenses, or refractive surgery in adults. In children, treatments like low-dose atropine, orthokeratology, and specialized lenses can slow progression but do not reverse existing refractive error. Management focuses on correction and, in children, controlling further progression.
Myopia vs hyperopia — what is the difference?
Myopia means light focuses in front of the retina, causing blurred distance vision while near vision is clear, and it is corrected with minus (concave) lenses. Hyperopia means light focuses behind the retina, often causing more trouble with near vision, especially with age, and is corrected with plus (convex) lenses. Both are common refractive errors but require opposite lens corrections.
Key drugs
Related conditions and differentials
Sources and further reading
StatPearls (NCBI Bookshelf)MedlinePlusWHO ICD-10: H52.1
Educational content for medical students, prepared by the WhiteCoat Pro editorial team with AI assistance; every page is reviewed by a second AI model for factual errors. It is not medical advice and does not replace the product label, local guidelines or a clinician.