Myopia (short-sightedness)

Causes

In people with short-sightedness, the clear front surface of the eye (the cornea) curves too steeply or the eyeball is too long. This means that light entering the eye does not focus on the back of the eye (the retina) but focuses in front of the retina so distant images appear blurry.

Basically, myopia occurs when the eyeball grows too quickly in childhood, or starts growing again in adulthood. Childhood onset myopia is most commonly caused by the eyes growing too quickly. Genetics, environment and the individual’s characteristics can all contribute to this excess growth.

Research suggests genes are partly responsible as short-sightedness tends to run in families and a person with one short-sighted parent has three times the risk of developing myopia – or six times the risk if both parents are short-sighted.

Short-sightedness may also be related to environmental factors. While genetics plus environmental factors are thought to play a role in the development of myopia, it is environmental factors which are driving the increase worldwide, especially in countries where children do not spend much time outside. Children who spend a lot of time focusing on near objects, for example, reading or watching a computer screen, may have a greater chance of becoming short-sighted. Lack of time spent outdoors in natural light has been shown to increase the chances of developing short-sightedness, with the hypothesis being that daily exposure to natural light is needed for the eyes to develop properly.

Adult onset myopia usually occurs as an adaptation to fatigued eye focusing muscles due to a significant increase in close work, such as university studies.

Myopia may also develop in adults due to visual stress or health conditions such as diabetes.

Myopia may also occur due to environmental factors or other health problems:

• Some people may experience blurred distance vision only at night. With "night myopia," low light makes it difficult for the eyes to focus properly. Or the increased pupil size during dark conditions allows more peripheral, unfocused light rays to enter the eye.
• People who do an excessive amount of near-vision work may experience a false or "pseudo" myopia. Their blurred distance vision is caused by overuse of the eyes' focusing mechanism. After long periods of near work, their eyes are unable to refocus to see clearly in the distance. Clear distance vision usually returns after resting the eyes. However, constant visual stress may lead to a permanent reduction in distance vision over time.

A recent report, The Australia and New Zealand Child Myopia Report – A Focus on Future Management surveyed 1,003 parents of children aged 0 to 18. The Child Myopia Working Group, an initiative which aims to set a recommended standard of care for child myopia management to slow progression of myopia in children, released the report.

It found that only 12 per cent of parents knew of lifestyle factors that impact on child myopia (low levels of outdoor activity, low levels of light exposure, prolonged near tasks such as reading and gaming on portable devices). It also revealed that one-third of Australian children had never been to an optometrist for an eye examination. Poor school performance can be a result of vision problems.

Myopia is rapidly becoming a serious public health concern yet this survey shows that 65 per cent of Australian parents, with children 0-17 years old, do not know what myopia is, and only 12 per cent recognise the health risks their children might develop later from high myopia. These include retinal detachment, glaucoma, cataracts and macular degeneration. People with high myopia need regular eye examinations to watch for changes in the retina.

One reason for the increased prevalence of high myopia is that myopia onset is occurring earlier - in 1983, typical onset was 11 years of age compared with eight years of age in 2000. And the earlier you develop myopia, the worse it is likely to be. People with high myopia have a higher risk of detached retina or macular degeneration so need regular eye examinations to watch for changes in the retina.

Photo credit: Photo by Laura Dewilde on Unsplash

Symptoms Of Myopia

You may be short-sighted if:

• you have difficulty seeing objects in the distance;
• objects in the distance appear blurry;
• you need to squint or partially close your eyes to see clearly;
• you get headaches that are caused by eyestrain;
• you have difficulty seeing while driving and have trouble reading road signs, especially at night.

The website childmyopia.com features an excellent vision simulator tool, enabling you to get an idea of vision with different scales of myopia. You just need to move the slider along the scale to see how vision without spectacles or contact lenses changes as short-sightedness increases.

Some signs that your child may be short-sighted include:

• screwing up their eyes or squinting to see objects in the distance;
• difficulty seeing the blackboard/whiteboard at school;
• sitting close to the television or needing to sit at the front of the classroom.

Myopia may also develop in adults due to visual stress or health conditions such as diabetes:

• • Symptoms of myopia may also be a sign of variations in blood sugar levels in people with diabetes or may be an early indication of a developing cataract.
  • Some people may experience blurred distance vision only at night. With "night myopia," low light makes it difficult for the eyes to focus properly. Or the increased pupil size during dark conditions allows more peripheral, unfocused light rays to enter the eye.
  • People who do an excessive amount of near-vision work may experience a false or "pseudo" myopia. Their blurred distance vision is caused by overuse of the eyes' focusing mechanism. After long periods of near work, their eyes are unable to refocus to see clearly in the distance. Clear distance vision usually returns after resting the eyes. However, constant visual stress may lead to a permanent reduction in distance vision over time.

As part of its children's vision campaign, Optometry Australia produced this video to highlight how children can feel excluded from day-to-day activities due to vision issues including myopia.

Video credit: Optometry Australia

Detecting Myopia

Optometrists diagnose short-sightedness by asking you to sit usually three to six metres away and read from a special chart called a Snellen chart that has large letters at the top and smaller letters at the bottom. This test measures visual acuity, the clarity or sharpness of vision.

The optometrist will then perform a series of tests, such as using special equipment like a retinoscope, and placing different lenses in front of your eyes. Retinoscopy is a good technique to find myopia, and especially so in young children who are non-verbal or cannot yet recognise alphabets on a vision chart. They will also use a slit lamp to magnify and light your eye so that they can see it in much closer detail to check your eye health.

These examinations can be conducted without using eye drops to determine how the eyes respond under normal seeing conditions. In some cases, such as for patients who can't respond verbally or when some of the eye's focusing power may be hidden (such as in children), an optometrist may use eye drops, called Cyclopentolate, which temporarily keep the eyes from changing focus during testing.

Using the information from these tests, along with results of other examinations of eye focusing and eye teaming (the ability of eyes to move, turn and point together,) your optometrist can determine if you have myopia. Your optometrist will be able to diagnose whether your myopia is mild, moderate or severe. He or she will also determine the power of any lens correction needed to provide clear vision and discuss treatment options.

You should visit an optometrist regularly throughout life. If you have myopia, it is important to maintain regular checks with your optometrist at their advice. For example, for a child, the optometrist may suggest regular reviews at 3-6 months or yearly. If you’re an adult, it might be every 1-2 years.

Treating Myopia

Myopia is a progressive condition but progression can be controlled if detected early enough. A cure has not been discovered but there are several ways to improve your vision if you have this eye condition. And the good news is research shows that there are ways to manage the onset and progression of myopia. Clinical trials involving children with myopia show it is feasible to diminish the progression for a better visual outcome.

Ways to correct your vision if you are short-sighted include:

• Wearing glasses – The most common treatment for myopia is corrective eyewear. While glasses correct vision and relieve symptoms when worn, they do not cure your myopia. Depending on the amount of myopia, you may only need to wear glasses for certain activities, like watching a movie or driving a car but if you are very short-sighted, you may need to wear them all the time. Generally, a single-vision lens is prescribed to provide clear vision at all distances but people aged over 40, or children and adults whose myopia is due to the stress of near-vision work, may need a bifocal or progressive addition lens. These multifocal lenses provide different powers or strengths throughout the lens to allow for clear vision in the distance and up close.
• Contact lenses are worn directly on the eye. You can wear soft contact lenses which are like glasses and correct vision and relieve symptoms while worn. For some individuals, contact lenses offer clearer vision and a wider field of view than eyeglasses.

Ways to slow the progression of myopia in children (otherwise known as ‘myopia control’):

• Some soft daily disposable contact lenses are designed to slow the progression of myopia in children. The single-use, disposable contact lenses correct the vision and may slow myopia progression in children. There are several of these soft myopia-control contact lenses available in the Australian market. It is best to speak to your optometrist to see which brand best fits and suits your child.
• Ortho-keratology contact lenses (known as ‘Ortho-K’) are only worn in bed at night while sleeping. In this nonsurgical procedure, you wear specially designed rigid ‘hard’ contact lenses to gradually reshape the curvature of your cornea, the window of the eye. The lenses place pressure on the cornea to flatten it which changes how light entering the eye is focused. You wear the contact lenses for limited periods, such as overnight, then remove them. People with mild myopia may be able to temporarily obtain clear vision for most of their daily activities. Research shows that starting ortho-k for children at a young age halves the risk of rapid progression in those whose myopia is progressing fast. This study found that the ideal age is six to less-than-nine years for children to start wearing overnight ortho-k contact lenses to control myopia. It further showed that older children, including adolescents, can also benefit from ortho-k significantly reducing myopia progression, if they showed rapid progression before treatment. There is now growing evidence of the effectiveness of ortho-k for myopia control in children. Not all optometrists prescribe ortho-k lenses but if your optometrist does not, they can refer you to one who does.
• Atropine eye-drops – Low concentration Atropine eye drops have been shown to slow progression of myopia in children and their use is gaining popularity. There are different formulations and many trials are ongoing. This may be a good myopia-control option for those children who cannot wear contact lenses. However there are pros and cons with using Atropine. It is important to speak with your optometrist.
• Having laser surgery – a laser beam is used to change the shape of your cornea. Laser procedures such as LASIK (laser in situ keratomileusis) or PRK (photorefractive keratectomy) are possible treatment options for myopia in adults. The beam reshapes the cornea by removing a small amount of eye tissue. In PRK, a thin layer of tissue is removed from the surface of the cornea in order to change its shape and refocus light entering the eye. LASIK removes tissue from the inner layers of the cornea. These techniques are performed by an eye surgeon (ophthalmologist).
• Other refractive surgery procedures. People who are highly short-sighted or whose corneas are too thin for laser procedures may be able to have myopia surgically corrected. A doctor may be able to implant small lenses with the desired optical correction in their eyes. The implant can be placed just in front of the natural lens (phakic intraocular lens implant), or can replace the natural lens (clear lens extraction with intraocular lens implantation). These techniques are performed by an eye surgeon (ophthalmologist).

The key message is we don’t have to sit back and watch our children’s vision get worse every year as there are things we can do about it. Optometrists can see signs of children who are heading towards becoming myopic even before they are myopic and alert parents to interventions including increased outdoor time. Changes are often quite subtle in myopia early on and parents don’t readily pick up if a child has reduced vision, so children should have eye examinations with an optometrist when pre-schoolers, before starting school, in middle school, before starting high school and more regularly if symptoms appear.

Atropine eye-drops are gaining popularity as a treatment to slow myopia progression.

Preventing Myopia

The causes of myopia are a mix of genes and environment. You can’t do much about your genes, but as environment is the trigger behind the increasing myopia epidemic, we can do something about that.

There is lots of evidence and evidence is building that it is probably outdoor light that affects eye growth and that outdoor light is a potentially useful intervention against myopia onset and progression. The catch-cry ‘more green time, less screen time’ is promoted by optometrists to encourage parents to urge their children to spend more time outside in natural light, and less time inside glued to screens. This is why traditionally Australia, with its sporty outdoors lifestyle, has had lower myopia rates than many Asian countries where children might spend more time inside on screens.

Australian optometrists were the first to show that increasing exposure to outdoor light was the key to reducing the myopia epidemic in children. Their ground-breaking research, the Role of Outdoor Activity in Myopia (ROAM) study, followed 101 children aged 10 to 15, of whom 41 were myopic and 60 were non-myopic, from 42 Brisbane schools.

Researchers, Associate Professors Scott Read, and Stephen Vincent and Professor Michael Collins, found that outdoor light appeared to be the main protective factor against myopia development and progression.

They said optometrists could now advise parents that children need to spend more than one hour and preferably at least two hours a day outside to help prevent myopia from developing and progressing.

Their study found no protective association with outdoor physical activity or reducing near work as suggested by some previous studies but suggested ‘near work’ on computer and other screens was not itself causing myopia although screens are responsible for children spending more time indoors.

Professor Read told Optometry Australia: “It would be prudent for optometrists to advise that less than 60 minutes a day exposure to light outdoors is a risk factor for faster eye growth and potentially becoming myopic and myopia progression.”

A review of 25 studies of myopia and outdoor light published in 2017 demonstrated a protective effect of improved outdoor time for onset of myopia, but not progression (once myopia was established). The researchers from China and the Brien Holden Vision Institute in Sydney, Australia found about an extra 1.25 hrs/day compared with control/baseline time spent outdoors reduced the risk of onset of myopia by 50 per cent.

Interestingly, time outdoors had a stronger protective effect in children aged 6 years compared with kids aged 11 to 12 years. The authors said: ‘It is well known that the various ocular components undergo growth and maturation in younger children, and thus, the ocular growth patterns may be more sensitive to environmental influences, including outdoor time, during this period.’

Another recent study found that adding 40 minutes daily of outdoor time led to less myopia in Chinese children.

More green time and less screen time helps prevent myopia. Photo by Bruno Saito from Pexels. Found here.

Other tips on how to slow or prevent myopia, from optometrists who are expert in child myopia, Drs Kate and Paul Gifford and their My Kids Vision website include:

• Catching early signs before it fully develops can slow onset and progression
• Children should not spend more than three hours a day – in addition to school time – on close work such as reading, homework or screen-time
• Ensure computers are properly positioned to avoid eye strain and take breaks every 20 minutes by looking across the room for 20 seconds
• Smart phones are popular for children and teenagers’ texting, social media, reading and games but too much screen time is linked to myopia, can cause dry eyes, and increase risk of eye damage and diseases in adulthood similar to UV damage
• Children should avoid the blue-white bright light from tablets and phones for three hours before bedtime as this can interfere with sleep
• Outdoor sport and play of at least 90 minutes a day can reduce risk of myopia
• Evidence suggests exposure to outdoor light is beneficial in slowing onset and progression of myopia but UV protection is important so wear sunglasses and a hat

In some Asian countries where child myopia rates are very high, they are considering measures such as building glass classrooms in China to expose children to more natural light to try to reduce myopia rates. And in Taiwan they have made outdoor time part of the curriculum and since they increased time outdoors to several hours daily, children’s vision is improving.

Commonly Asked Questions

What is Myopia?

Myopia, or short-sightedness as it is commonly known, is an eye condition where you do not see distant objects clearly. Myopia is a very common eye condition that usually begins in school-age children and can continue to progress until the eye stops growing. Adults can also develop myopia.

What Causes Myopia?

If the clear window at the front of the eye called the cornea is too curved, or your eye is too long, light that enters the eye will not focus correctly on the retina at the back of the eye. How does this occur? Research has shown that the development of myopia is influenced by both genetic and environmental factors, but an increase in myopia in recent years indicates that environmental factors are probably more prevalent. Research has shown that adequate daily exposure to sunlight can curb the onset of myopia.

Can Myopia Be Cured?

Despite ongoing research, a cure for myopia has not yet been found. Properly prescribed glasses or contact lenses will help you to see clearly but will not cure your shortsightedness. Some eye surgery techniques can correct myopia in some people and eliminate the need for glasses or contact lenses.

What Are The Treatments?

See section above but these include glasses, specially designed contact lenses and eye-drops to reduce progression.

Will I Have To Wear Glasses?

Your optometrist will tell you if you need to wear glasses full-time or part-time to enable you to see clearly. Sometimes you will need them only for some activities such as driving, going to the movies or in the classroom.

Many short-sighted people use both glasses and contact lenses to help them see clearly. Glasses are used not only to correct vision, they also make a fashion statement and come in many shapes, sizes and colours. Contact lenses are worn on the eyes. They may provide better vision and are great for people with an active lifestyle.

How Can I Tell If I'm Short-Sighted and How Will It Affect Me?

Short-sighted people will see distant objects as a blur. Some people do not realise that they cannot see clearly but an eye examination by an optometrist will test for myopia.

Your optometrist will tell you if you need to wear glasses all the time or some of the time, depending on the severity of myopia and according to your lifestyle. In some instances, you may only need them for some activities such as driving, going to the movies or in the classroom.

Optometrists use an eye chart to test your visual acuity, or how well you see in the distance, and place different lenses in front of your eyes to find the lenses that give you the clearest vision on the eye chart. Using these results and other tests, your optometrist can tell if you are short-sighted.

How Can I Tell If My Child Is Short-Sighted?

A comprehensive eye examination is the only sure way of determining whether your child’s vision is normal. Some clues to myopia in a child are:

• Screwing up their eyes to see distant objects
• Difficulty reading the blackboard at school or TV at home
• Poor posture while reading
• Lack of interest in playing outdoor games

Australian optometrists Kate and Paul Gifford have developed the My Kids Vision website, including a free online tool that helps parents assess and manage myopia risks for their kids. The survey asks six questions then gives advice on your child’s risk of developing myopia and of myopia worsening.

Where Do I Get More Advice?

We recommend making an appointment with an optometrist for a comprehensive eye examination. Comprehensive eye examinations, at regular intervals starting from childhood, ensure that most eye conditions can be prevented or corrected. Eye examinations can also be an important tool for determining your overall health.

Use our Find an optometrist search function if you do not have an optometrist, or would like to find an optometrist close to where you live.

Published date: 01 September 2016 Reviewed date: 24 April 2020

Author: Luke Arundel, BAppSci (OPtom) Hons, FIACLE, FCCLSA, FBLSA, FBCLS, AdjAssProf University of Missouri St Louis, GCOT, CASA CO

Bio: Luke Arundel is Chief Clinical Officer of Optometry Australia. He graduated with Honours in Optometry from Queensland University of Technology in 1998 and has worked extensively in Australia and Ireland. He currently holds fellowships with the BCLA, CCLSA and IACLE and became an Adjunct Associat Professor of the University of Missouri, St Louis, USA in 2008. His professional interests include keratoconus, post-graft and scleral lens fitting, dry eye, ortho-keratology and paediatric contact lenses. He has worked in specialty contact lens practices in Brisbane and Melbourne and in the contact lens manufacturing field along with time in the public health and education sectors. Luke’s role at Optometry Australia sees him provide professional services assistance to members in audits, investigations and medico-legal matters along with leading development of resources and special projects.

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Disclaimer: No information provided on the Good vision for life website is intended to constitute or substitute advice from visiting an optometrist. Many factors unknown to us may affect the applicability of any information on this website. You should seek appropriate personalised advice from a qualified optometrist about any eye health and vision conditions.