Myopia (Nearsightedness): Causes, Progression and Myopia Control

Myopia, also called nearsightedness or short-sightedness, means that you see close objects clearly but distant ones look blurry. It is the most common eye condition in children and young adults, and it is becoming more common almost everywhere. In parts of East Asia, a large majority of young adults are now myopic, and researchers have projected that around half of the world's population could be myopic by 2050 if current trends continue.

For many people, myopia is simply a nuisance solved by glasses or contact lenses. But myopia is more than a need for spectacles. The higher it becomes, the greater the lifetime risk of serious eye conditions such as retinal detachment and myopic macular degeneration. That is why eye care professionals now focus not only on correcting myopia but also on slowing its progression in children. This guide explains what causes myopia, how it develops, what high myopia means for long-term eye health and which myopia control options are backed by evidence.

What is myopia?

In a normal eye, the cornea and lens focus light from distant objects precisely onto the retina. In a myopic eye, the light comes to a focus in front of the retina, so by the time it reaches the retina it is spread out and blurry. Close objects, whose light rays are diverging, focus further back and so can still appear sharp.

Most myopia is axial: the eyeball is longer than normal from front to back. Each extra millimetre of length adds roughly 2.5 to 3 dioptres of myopia. Less commonly, myopia results from a cornea or lens with too much focusing power. For an overview of how myopia compares with other focusing problems, see our guide to refractive errors.

Myopia is measured in dioptres with a minus sign. As a rough guide:

Symptoms

• Blurred distance vision, such as difficulty reading the board, road signs or subtitles
• Squinting to see distant objects
• Sitting close to the television or holding devices very close
• Eye strain or headaches
• Worse vision at night or in dim light (sometimes called night myopia)
• In children: lack of interest in distant activities, poor performance in ball sports, or a teacher noticing difficulty

Children rarely complain about blurry vision, because they assume everyone sees the same way. Regular eye checks are the only reliable way to detect myopia early.

What causes myopia?

Myopia develops through an interaction between genetic predisposition and environmental factors that influence how the eye grows during childhood.

Genetics

Children with one myopic parent are more likely to become myopic, and the risk is higher still when both parents are. Hundreds of genetic variants linked to myopia have been identified, mostly involved in signalling pathways that control eye growth. However, genetics cannot explain why myopia has become so much more common within just a few generations; the environment has changed much faster than our genes.

Time outdoors

One of the most consistent findings in myopia research is that children who spend more time outdoors are less likely to develop myopia. Randomised trials in schools in East Asia found that adding outdoor time reduced the number of children becoming myopic. Researchers think the much higher light levels outdoors, which can be many times brighter than indoor lighting even on a cloudy day, stimulate the release of dopamine in the retina, which helps regulate eye growth. Viewing distant scenes may also play a role. Read more in our article on outdoor time and childhood myopia.

Near work and screens

Prolonged, intensive near work, such as reading, studying and using phones or tablets at short distances, is associated with a higher risk of myopia, although the evidence is less consistent than for outdoor time. Holding material very close and reading for long periods without breaks appear to matter most. Screens are probably harmful mainly because they encourage long periods of close focus and replace time outdoors, rather than because of blue light. Our article on why myopia is rising worldwide explores these factors.

Other factors

• Starting school early and intensive education systems
• Urban living with less access to open spaces
• Ethnicity: myopia rates are particularly high in East Asian populations
• Rarely, myopia is part of a genetic syndrome or caused by conditions such as keratoconus, cataract or premature birth
• Temporary myopic shifts can occur with high blood sugar or certain medications

How myopia progresses in children

Myopia usually first appears between about 6 and 14 years of age. Once it starts, it typically increases each year as the eye continues to lengthen, until growth slows in the late teens or early twenties. A few general patterns are important:

• Earlier onset means more progression. A child who becomes myopic at 6 or 7 has many more years of progression ahead than one who becomes myopic at 14, and is more likely to reach high myopia.
• Progression is often fastest in younger children and slows with age.
• Adult-onset myopia also occurs, often in people doing intensive near work, but it is usually milder.

Because every dioptre of myopia avoided reduces the long-term risk of complications, many eye care professionals now recommend active myopia management for children whose myopia is progressing, rather than simply updating glasses each year. Measuring eye length (axial length) with optical biometry is increasingly used to monitor growth more precisely.

Why high myopia matters: long-term complications

A long, myopic eye is a stretched eye. The retina, choroid and sclera become thinner, particularly at the back of the eye. This stretching increases the risk of several sight-threatening conditions later in life, even when glasses or surgery give perfectly clear vision.

The risk rises with the degree of myopia, but even low and moderate myopia carry some increase in risk compared with no myopia. Importantly, laser surgery corrects the focus but does not shorten the eye, so these risks remain after refractive surgery. People with high myopia should have regular dilated eye examinations throughout life. Learn about the warning signs in our guide to retinal detachment.

Myopia control: slowing progression in children

Myopia control means using treatments that slow the elongation of the eye, not just correcting blur. No treatment stops myopia completely or reverses it, but several have good evidence of slowing progression. The choice depends on the child's age, prescription, lifestyle, family preferences and local availability. Treatment is usually continued for several years and monitored regularly.

Low-dose atropine eye drops

Atropine is an old drug that, at normal strength, dilates the pupil and paralyses focusing. Studies including the ATOM trials in Singapore and the LAMP study in Hong Kong showed that much lower concentrations can slow myopia progression with far fewer side effects, such as light sensitivity and near blur. Effectiveness appears to vary with concentration and between individuals, and some children may experience a rebound when treatment stops abruptly. Availability and approved products differ between countries. The concentration and duration are decided by the prescribing eye doctor; do not use regular-strength atropine or compounded products without medical supervision.

Myopia control spectacle lenses

Special spectacle lenses correct distance vision in the centre while creating zones of so-called myopic defocus in the periphery, which appear to signal the eye to slow its growth. Examples include lenses using Defocus Incorporated Multiple Segments (DIMS) technology and lenses with Highly Aspherical Lenslets (HAL). Clinical trials have shown meaningful reductions in both progression and eye elongation compared with standard single-vision lenses. They are non-invasive and suit children who are not ready for contact lenses, but they must be worn consistently, ideally all day, to work.

Myopia control soft contact lenses

Dual-focus or multifocal soft contact lenses provide clear central vision with peripheral defocus rings. A daily disposable dual-focus lens (MiSight) became the first contact lens approved by the US Food and Drug Administration specifically to slow myopia progression in children, following a multi-year randomised trial. Other multifocal designs are also used. Children as young as 8 can often handle daily disposable lenses safely with parental supervision, which keeps infection risk low.

Orthokeratology (ortho-k)

Ortho-k lenses are specially designed rigid gas-permeable lenses worn overnight. They gently reshape the cornea while the child sleeps, allowing clear vision during the day without glasses, and the altered corneal shape also produces peripheral defocus that slows eye growth. Ortho-k is effective but requires careful fitting, excellent hygiene and regular follow-up, because overnight lens wear carries a small but real risk of serious corneal infection.

Prevention and everyday habits

Lifestyle changes cannot replace medical myopia control in a child whose myopia is progressing, but they are important for prevention and as part of overall care:

• Spend time outdoors: many experts suggest aiming for around two hours of outdoor time a day for children, through play, sport or walking. Daylight matters more than the specific activity. Use hats and sunglasses in strong sun.
• Take breaks from near work: for example, look up at something far away regularly. The 20-20-20 rule is an easy reminder.
• Keep a good reading distance: encourage children not to hold books or screens too close; roughly an elbow-to-knuckle distance is a practical guide.
• Limit recreational screen time in young children, in line with paediatric guidance.
• Good lighting for homework and reading.
• Regular eye checks, especially if parents are myopic.

Our guide to eye health in children has more practical advice for families.

Correcting myopia in adults

For adults, myopia is corrected with glasses, contact lenses or refractive surgery once the prescription has been stable. Options include LASIK, PRK, SMILE and, for higher prescriptions or thin corneas, implantable lenses. Surgery can provide excellent vision, but it does not remove the higher risk of retinal problems in long eyes, so regular examinations remain important. Myopic adults often find in their 40s that they can read without glasses because presbyopia is offset by their myopia.

Can eye exercises cure myopia?

No. Myopia is mainly caused by the physical length of the eyeball, which exercises cannot change. Despite popular claims, including those associated with the Bates method, there is no reliable scientific evidence that eye exercises, palming or special eye yoga reverse or cure myopia. Relaxation exercises may make the eyes feel more comfortable during long periods of near work, and that is a reasonable goal, but they should never replace proper correction or evidence-based myopia control in children.

When to see a doctor

Book an eye examination if you or your child has difficulty seeing in the distance, squints, has headaches, or has not had an eye test recently. If your child is myopic, ask the optometrist or ophthalmologist about myopia control options, particularly if the prescription is increasing each year or myopia started at a young age. Adults with high myopia should have regular dilated eye exams, even if their vision seems fine.