Myopia (Nearsightedness)

How myopia works

In a normal eye, the cornea and lens focus light precisely onto the retina. In myopia, light focuses in front of the retina because:

• the eyeball is too long from front to back (axial myopia, by far the most common), or
• the cornea or lens is too curved (refractive myopia)

Near objects send diverging light, which focuses farther back, so they still look clear.

Myopia is measured in diopters with a minus sign. Mild myopia is roughly up to -3.00, moderate -3.00 to -6.00, and high myopia -6.00 or more.

Myopia vs other refractive errors

Many people have more than one. See refractive errors.

Causes and risk factors

• genetics: having one or both nearsighted parents raises a child's risk
• less time outdoors: outdoor light appears to slow eye growth; this is one of the strongest modifiable factors
• prolonged near work: reading, screens and close-up activities
• early onset: myopia starting before age 8 to 10 tends to progress further
• ethnicity: higher rates in East Asian populations
• education level and urban living

Symptoms

• blurry distance vision (road signs, the classroom board, TV)
• squinting to see clearly
• eye strain and headaches
• difficulty seeing while driving at night

In children

Children often do not realize their vision is blurry. Watch for:

• sitting close to screens or holding devices near the face
• squinting or rubbing eyes
• not noticing distant objects
• poor school performance or losing interest in sports needing distance vision

Diagnosis

An optometrist or ophthalmologist checks:

• visual acuity with an eye chart
• refraction to measure the prescription, often with drops to relax focusing in children (cycloplegic refraction)
• eye health with a dilated retinal exam
• axial length measurement, increasingly used to track progression in children

Children should have vision screening at well-child visits and a full exam if they fail screening or have symptoms.

Correction

• glasses: simple and safe
• contact lenses: soft or rigid
• refractive surgery for adults with a stable prescription: LASIK, PRK and SMILE reshape the cornea; implantable lenses are options for high myopia

Correction does not change eye length, so the risks of high myopia remain after surgery.

Slowing myopia in children (myopia control)

Slowing progression lowers the chance of high myopia and its complications. Options include:

• outdoor time: about 2 hours a day of outdoor activity may reduce the onset of myopia
• low-dose atropine eye drops: nightly drops that slow progression; several concentrations are used
• myopia control spectacle lenses: special glasses with defocus designs that slow eye growth
• myopia control soft contact lenses: dual-focus daily lenses, one of which is FDA-approved for children
• orthokeratology: rigid lenses worn overnight to temporarily reshape the cornea
• near-work habits: breaks from close work, such as the 20-20-20 rule (every 20 minutes, look 20 feet away for 20 seconds), good lighting and keeping books at a reasonable distance

An eye care professional can recommend the right approach based on age, prescription and progression.

Complications of high myopia

High myopia stretches the eye's tissues and increases the long-term risk of:

• retinal detachment
• myopic maculopathy, including bleeding vessels under the retina (choroidal neovascularization)
• glaucoma
• early cataract

These can cause permanent vision loss, so people with high myopia need regular dilated eye exams and should know the warning signs of retinal detachment.

Frequently asked questions

What is myopia?

Myopia, or nearsightedness, is a common refractive error in which distant objects look blurry while near objects are clear. It usually occurs because the eyeball is slightly too long, so light focuses in front of the retina.

Can myopia be cured?

Glasses, contacts and refractive surgery correct the blur, and surgery can remove the need for glasses in adults. However, they do not change the eye's length or the risks linked to high myopia. In children, treatments can slow progression but do not reverse it.

How can I stop my child's myopia from getting worse?

Encourage about 2 hours a day outdoors, regular breaks from near work, and ask an eye care professional about myopia control options such as low-dose atropine drops, special glasses, myopia control contact lenses or orthokeratology.

Does screen time cause myopia?

Prolonged near work, including screens, is associated with myopia, alongside genetics and limited outdoor time. Screens themselves are not the only factor. Regular breaks, good distance and more outdoor time help reduce risk.

At what age does myopia stop getting worse?

Myopia usually progresses through childhood and the teen years and tends to stabilize in the early to mid 20s. In some people it continues to change slowly into adulthood, especially with intensive near work.