Myopia

Myopia is a common eye condition affecting millions worldwide, where distant objects appear blurry while close objects remain clear. Understanding this condition and the available treatment options can help protect your vision and reduce the risk of serious eye problems later in life.

Table of contents

• What is myopia?
• How common is myopia?
• Types of myopia
• Signs and symptoms
• What causes myopia?
• Risk factors
• How is myopia diagnosed?
• Treating blurred vision
• Slowing myopia progression
• Potential complications
• Prevention strategies

nearsightedness, short-sightedness

What is myopia?

Myopia is the medical name for nearsightedness, which means you can see objects that are near clearly but have difficulty seeing objects that are farther away^[1]. For example, if you have myopia, you may not be able to make out highway signs until you’re just a few feet away, or you might struggle to see a whiteboard in a classroom^[3].

Myopia happens when the shape of the eye — or the shape of certain parts of the eye — causes light rays to bend incorrectly. Light rays that should be focused on nerve tissues at the back of the eye, called the retina (a light-sensitive layer of tissue), are focused in front of the retina instead^[3]. This occurs because the eyeball grows too long from front to back, or less commonly because the cornea (the clear front cover of the eye) is too curved^[2].

How common is myopia?

Myopia is very common. According to one estimate, more than 40% of people in the U.S. have nearsightedness^[1]. Myopia affects nearly 30% of the U.S. population, and this number is rapidly rising, especially among school-aged children^[1][4]. Eye experts expect this trend to continue in the coming decades.

The worldwide prevalence of myopia is increasing dramatically. It is estimated that approximately 30% of people around the world have myopia^[2], and it is expected that nearly half of the people on the planet will be nearsighted by 2050^[5]. One in four parents has a child with some degree of nearsightedness^[1].

Types of myopia

Eye specialists divide myopia broadly into two main types: simple myopia and pathologic myopia^[1]. Pathologic myopia is also known as degenerative or malignant myopia^[7].

People with simple myopia (also called school myopia or non-pathological myopia) have contact lenses or eyeglasses that help provide clear vision. This type of myopia usually starts in childhood or adolescence, and after adolescence, vision usually stabilizes and doesn’t get worse^[1][7].

Those with pathologic myopia may not be able to have clear vision even with corrective lenses^[1]. This is a rare type that is usually inherited from parents. When myopia prescription goes above -5 diopters (a unit measuring the focusing power needed for vision correction), this is considered high myopia^[17].

Signs and symptoms

If you have nearsightedness, you may notice faraway objects look blurred or fuzzy, while close items appear clear^[1]. Other symptoms may include headaches and eye strain^[2].

Common symptoms of myopia include:

• Blurry vision when looking at distant objects
• The need to squint or partially close the eyelids to see clearly
• Headaches
• Eye strain (when your eyes feel tired or sore)
• Tiredness when driving, playing sports, or looking more than a few feet away^[1][3]

School-age children may have difficulty seeing things on whiteboards or screen projections in the classroom^[3]. Younger children might not express difficulty seeing, but they may show certain behaviors that suggest trouble with vision. Some additional symptoms to watch for in children include:

• Constant squinting
• Poor performance in school
• Shortened attention span
• Holding objects close to their face
• Seeming to not be aware of distant objects
• Blinking often
• Rubbing the eyes often
• Sitting close to the television or moving screens closer to the face^[1][3]

If you have mild nearsightedness, you may not notice any symptoms. That’s why it’s important to get regular eye exams — so your doctor can make sure you’re seeing as clearly as possible^[6].

What causes myopia?

Eye experts are still unsure of the exact cause of myopia, but believe it to be a mix of hereditary and environmental factors^[1][2]. If you have myopia, more than likely at least one or both of your biological parents do, too^[1].

Myopia results from the length of the eyeball growing too long or less commonly the lens being too strong^[2]. It’s possible that you can inherit the ability to be myopic. If your lifestyle produces just the right conditions, you’ll develop it. For example, if you use your eyes for a lot of close-up work, like reading or working on a computer, you may develop myopia^[1].

Myopia usually appears in childhood. Typically, the condition can worsen in early childhood but tends to level off by the end of teen years^[1]. Nearsightedness usually develops during childhood and adolescence, and typically it becomes more stable between the ages of 20 and 40^[3].

Because the light coming into your eyes doesn’t focus correctly, images are unclear. Light that should focus on the retina instead focuses in front of it, causing distant objects to look blurry^[1][2].

Risk factors

Anyone can be nearsighted, but certain factors increase your chances of developing myopia:

Family history: If one parent has myopia, a child has a 25% chance of developing it. If both parents are myopic, the likelihood jumps to 50%^[15]. If one or both of your parents are nearsighted, there is an increased chance their children will be nearsighted^[4].

Spending a lot of time doing close-up work: Individuals who spend considerable time reading, working at a computer, playing video games or doing other intense close visual work may be more likely to develop myopia^[1][4]. High levels of screen time on smart devices is associated with around a 30% higher risk of myopia, and when combined with excessive computer use, that risk rose to around 80%^[4].

Not spending enough time outdoors: Children who spend more time outdoors are less likely to be nearsighted^[6]. Myopia is less common in people who spent more time outside during childhood^[2]. Certain studies indicate that spending less time in natural sunlight may play a role in the eye’s development and contribute to the onset of myopia^[16].

Ethnicity: Some groups of people have higher rates of myopia than others^[1].

Age at onset: Typically, the earlier a child develops myopia, the more time it has to progress, and the more likely they are to develop high myopia^[17]. Nearsightedness usually starts between ages 6 and 14 and gets worse until your early twenties^[6].

How is myopia diagnosed?

Eye doctors can check for nearsightedness as part of a comprehensive eye exam. The exam is simple and painless^[6]. A basic eye exam can confirm nearsightedness^[3].

Testing for myopia may use several procedures to measure how the eyes focus light and to determine the power of any optical lenses needed to correct the reduced vision^[4]. As part of the testing, you will identify letters on a distance chart. This test measures visual acuity (the sharpness of your vision), which is written as a fraction, such as 20/40^[4].

The top number of the fraction is the standard distance at which testing is performed (20 feet). The bottom number is the smallest letter size read. A person with 20/40 visual acuity would have to get within 20 feet to identify a letter that could be seen clearly at 40 feet in a normal eye. Normal distance visual acuity is 20/20, although many people have 20/15 (better) vision^[4].

Using an instrument called a phoropter, a doctor of optometry places a series of lenses in front of your eyes and measures how they focus light. The doctor may choose to use an automated instrument that evaluates the focusing power of the eye. The power is then refined based on your responses to determine the lenses that allow the clearest vision^[4].

Diagnosis is by the use of cycloplegics (eye drops that temporarily relax the focusing muscles) during eye examination^[2]. In some cases, such as for patients who can’t respond verbally or when some of the eye’s focusing power may be hidden, a doctor may use these eye drops^[4].

Treating blurred vision

Most cases of myopia are mild and easily managed with eyeglasses, contact lenses or refractive surgery^[1]. You can correct the blurry vision with eyeglasses, contact lenses or refractive surgery^[3]. Myopia treatments include glasses, contact lenses or surgery^[1].

Eyeglasses

Eyeglasses are the simplest and safest method of correction^[2]. The easiest and most common way to correct myopia, especially with children, is with eyeglasses^[13]. Eyeglass lenses correct the angle at which light hits your retina^[13].

Contact lenses

Contact lenses can provide a relatively wider corrected field of vision, but are associated with an increased risk of infection^[2]. Vision tests and eye examinations determine the prescription for your lenses just as they do for glasses, and contact lenses correct your vision in the same way by changing the direction in which light enters the eye^[13].

There are different types of contact lenses available:

Soft lenses are made of very pliable soft plastic that flexes and adheres to the surface of your eye exceptionally easily. Some soft lenses are meant to be taken out, cleaned, and stored overnight, and others are meant to be disposed of after being worn a certain number of times or for a certain time period, from a day to a few weeks^[13].

Rigid gas-permeable lenses are smaller lenses made of thin, rigid plastic. They float on your tears, and oxygen travels through them to the surface of your eye. They generally are not meant to be slept in, although there are specific extended-wear types that allow this^[13].

Refractive surgery

Adults can also get surgery to treat nearsightedness. The surgery changes the shape of your cornea so it can focus light clearly^[6]. For permanent correction of myopia, you will want to consider refractive surgery, which changes the eye permanently and usually requires no daily correction afterward^[13].

Refractive surgeries such as LASIK (laser-assisted in situ keratomileusis) and PRK (photorefractive keratectomy) permanently change the shape of the cornea^[2]. LASIK is the most common eye surgery procedure, which can correct nearsightedness and other refractive errors. PRK is similar to LASIK, but does not cut a flap from the front of the cornea. In this procedure, the laser corrects the shape of the eye directly on its surface^[13].

Other procedures include implantable collamer lens (ICL) placement inside the anterior chamber in front of the natural eye lens. ICL does not affect the cornea^[2]. People with the highest level of nearsightedness may want to consider implantable contact lenses^[13].

Slowing myopia progression

While myopia cannot be cured or reversed, treatment options are available to slow myopia progression in children and teenagers^[18]. In 2003, a multi-center clinical trial funded by the National Institutes of Health was the first to show that the myopic growth of the human eye could be slowed with an optical intervention in U.S. school-aged children^[9].

Slowing the progression of myopia by small amounts has big rewards. Children can maintain healthy eyesight and reduce the risk of problems when they reach adulthood. A small reduction in progression for adults can reduce the risk for more serious vision issues by as much as 40%^[15].

There is no single treatment which is clearly better than the rest. Specific spectacle lenses, soft contact lenses, orthokeratology and the best concentration of atropine eye drops appear to have a similar effect to slow myopia progression in children^[12].

Special spectacle lenses

Standard single-focus spectacles do not slow the worsening of childhood myopia but specific designs do. The most effective spectacle lens options for myopia control are special designs with ‘lenslets’ – numerous, 1mm sized mini-lenses scattered across the surface of the main spectacle lens. New types of ‘lenslet’ designs appear to be the most effective in slowing childhood myopia progression^[12].

Multifocal contact lenses

Multifocal contact lenses have been evaluated for slowing down an increase in myopia. In 2019, MiSight contact lenses became the first FDA-approved treatment for myopia control in the United States. These are a daily disposable contact lens that must be fit by a specialty-trained optometrist or ophthalmologist^[10]. There are numerous soft contact lens options with evidence for myopia control in children and teens^[12].

Orthokeratology (Ortho-K)

Orthokeratology, also known as Ortho-K, involves using rigid gas permeable contact lenses every night to reshape the clear, front part of the eye (known as the cornea). These specially designed gas-permeable contact lenses are worn overnight. The lenses gently reshape the cornea while you sleep, allowing for clear vision during the day without the need for glasses or daytime contacts^[10][11]. Ortho-K has been clinically proven to slow the progression of myopia in children and is ideal for active kids and teens who want freedom from daytime lenses^[11].

Atropine eye drops

Low-dose atropine eye drops are another effective treatment for managing myopia progression. Used once nightly, these medicated drops have been shown to significantly slow the elongation of the eye in children with minimal side effects^[11].

Multiple studies worldwide have shown that low doses of atropine eye drops can slow the increase in myopia. The lower dose of 0.01% atropine has consistently been shown to be effective at decreasing the rate of increasing myopia, with fewer side effects compared to the higher doses of atropine (i.e., less to no light sensitivity and blurred near vision)^[10].

This use of atropine eye drops requires the use of eye drops every day, likely for at least 1-2 years. Because this is a lower than normal dose of atropine, it requires a special pharmacy to make the eye drops^[10].

Potential complications

Severe myopia is associated with an increased risk of serious eye conditions. People with severe nearsightedness (also called high myopia) may be at higher risk for conditions like retinal detachment (when the retina is pulled away from its normal position)^[2][6].

The most common complications associated with myopia include:

• The retina thinning with age, which can lead to tears, holes and/or retinal detachment
• Increased eye pressure, which may lead to glaucoma
• Higher likelihood of developing cataracts
• Increased risk of macular degeneration (damage to the part of the retina responsible for central vision)
• Eyes injure more easily
• Increased risk of permanent vision loss^[17]

Every diopter increase in myopia (say, from –2D to –3D) increases the risk of myopia macular degeneration by 67%^[17]. The lengthening of the eye strains its delicate structures, leading to complications later in life. This is why even though high myopia has the highest eye health risks, there is no safe level of myopia. Even lower levels of myopia could pose an increased risk of eye issues^[17].

Prevention strategies

While the exact cause of myopia is unknown, there are strategies that may help prevent or slow its progression, especially in children.

Spend time outdoors

Studies have found that time spent outdoors can help prevent or delay the onset of myopia or halt or slow its progression^[20]. While more research is ongoing, factors such as the 3D nature and bright light that come with time spent outdoors have a positive effect on slowing the development and progression of myopia^[20].

Spending time outdoors is one of the most effective ways to reduce the risk of myopia progression. Exposure to natural light and opportunities to focus on distant objects help the eyes grow and function properly. Studies show that children who spend at least 2 hours outside daily are less likely to develop myopia than those who stay indoors^[20][21].

Limit screen time and near work

Some studies have found a correlation between screen time and near work with the onset of myopia. Further research is needed to understand why excess viewing on devices and near work may influence myopia^[20].

Encourage children to follow the 20-20-20 rule: for every 20 minutes spent looking at a screen, take a break by looking at least 20 feet (or 6 meters) away for 20 seconds^[20]. It’s recommended to limit screen time to a maximum of two hours per day^[20].

Regular eye exams

It is important to provide comprehensive eye exams to children early to delay the onset or slow the progression of myopia. The signs of a child becoming myopic may already be evident in 4 year-olds^[20].

Encourage pre-school age children to come in for a comprehensive eye exam. Follow-up with yearly examinations or twice a year for children at particular risk^[20]. The best way to stay on top of your myopia long-term is to ensure you’re getting a yearly eye exam^[15].