Myopia (short sightedness)

This page contains a summary of our information on myopia. To read our full information, download our factsheet:

Light rays enter the front of our eye. The cornea (clear front window) and the lens bend the light and focus it on the retina at the back of the eye. This gives us a clear, sharp image.

For vision to be clear, light entering your eye needs to be focused accurately on your retina. Light is first focused by the cornea and then finely focused by the lens inside your eye. If someone has no focusing error, this focusing system works perfectly and light entering their eye, is accurately focused onto their retina. This means their vision is clear and sharp.

In myopia, light entering the eye focuses in front of the retina instead of directly on it. This happens because the eyeball is longer than normal, or the cornea is more steeply curved. This makes vision blurry in the distance.

To correct this, people with myopia need glasses or contact lenses with a minus (-) lens prescription to correct their vision. This minus lens reduces how much the light is bent by the eye, so that it’s focused onto the retina rather than in front of it. The result is a clear sharp image.

Myopia can start at any age but usually starts in children from age 5. It tends to worsen in childhood and teenage years. When myopia increases, a stronger glasses or contact lenses prescription is needed. These changes can happen at any age but are more likely the younger you are when myopia starts, or if you already have higher levels of myopia. For many people myopia eventually stabilises in adulthood and may stay the same for many years.

It’s not known what causes myopia. Research suggests there could be several different reasons why you may become short sighted.

• Family history.  Myopia often runs in families so is thought to be partly genetic. Children who have one parent with myopia have a higher chance of developing it. This chance increases if both parents have myopia.
• Ethnic background. People of East Asian and South Asian ethnicity have a higher risk of developing myopia.
• Environmental causes. Spending too little time outdoors in daylight and reading books, looking at screens or doing other near work for long periods are thought to increase the risk of myopia developing.

Optometrists (opticians) measure the focusing power of your eye in dioptres. This is how strong a lens has to be to correct the focusing error of your eye and give you clear vision.

Myopia is written with a minus power on your glasses or contact lens prescription. For example, a prescription may be written as: -3.50 dioptres (D). The minus sign indicates that the lens is correcting for myopia. The figure 3.50 indicates the strength of the lens needed to correct the myopia. The higher the number, the more short sighted you are.

• Mild myopia includes powers up to -3.00D
• Moderate myopia includes powers of -3.00D to -6.00D
• High myopia is usually a power over -6.00D

If you have high myopia, you may have a greater risk of developing certain other eye conditions. The higher your myopia, the higher your risk. However, this is not the case for everyone with high myopia. For most people their eyes will remain healthy.

Some adults with high myopia can have an increased risk of developing eye conditions such as:

• posterior vitreous detachment (PVD)
• retinal detachment
• glaucoma
• cataracts
• pathological myopia

Myopia tends to get worse in children and teenagers as they grow. In general, children who become short sighted before the teenage years tend to become more myopic over time compared to those who develop myopia at a later age. Myopia usually stops getting worse around the age of 20 when the eye has stopped growing.

The current advice is that children should spend some time each day doing outdoor activities in natural daylight, all year round. Spending more time outdoors may help prevent or delay myopia from developing in children. It may also help children who already have myopia by slowing its worsening, but the evidence for this is not as strong. Spending more time outdoors might be difficult in the autumn and winter due to the darker evenings. But this can be made up for during the spring and summer when the evenings are lighter for longer. Walking to and from school where possible or playing in the garden once home from school, are simple ways of children spending time outdoors in daylight.

Long periods of reading and screen use may also affect how myopia develops. Although children should be encouraged to read and do school work, reducing the time spent close up on mobile phones, computer screens, or tablets can help to lessen long periods of close work.

Myopia management

Treatment to slow down how quickly myopia gets worse is called myopia management.

Slowing the progression of myopia may help protect the eyes from becoming very short sighted in the future. This means you may rely less on glasses or contact lenses to see clearly which can be beneficial for activities such as contact sport or swimming. You may not need expensive thinner, lighter lenses and the glasses can look and feel better, making them more comfortable to wear, especially for children.

Myopia management can also help reduce the risk of more serious eye conditions, later in life, such as retinal detachment or pathological myopia. These risks are higher in people with myopia, and they increase the more short sighted someone is. However, it’s important to remember that these serious eye conditions are still quite rare in the general population. Research is ongoing and over time it’s likely there will be a clearer idea of the full benefits of myopia management and how well different treatments work in the long term.

Currently, several studies have looked at treatments involving special glasses or contact lenses or eye drops to try to slow the progression of myopia in children. These myopia management treatments do not stop myopia from developing in the first place, but they can slow down progression significantly. Also, there are no studies or evidence to suggest that they would work for adults with myopia.

These treatments are not yet available through the NHS. They are available from many high street optometrists privately.

Myopia management does not “cure” myopia—it can help slow down how quickly it gets worse and reduce how strong a child’s prescription may become in future. It may also reduce risks of vision problems later in life.

Current evidence suggests that using myopia control contact lenses or glasses may reduce progression of the level of myopia by around 0.50D - 0.75D per year compared with using regular contact lenses or glasses. The reduction varies from child to child and may be lower or higher than this value. Treatment may need to be continued to maintain this reduction.

Ongoing research is required to understand how effective myopia management is in the long term. If myopia management is successful it may result in a child having a lower level of myopia than if they didn’t have the treatment, reducing their risk of developing a related eye condition later in life.

Your child’s optometrist will explain how they plan to monitor the treatment’s progress. There’s no way to be completely certain how much the treatment will reduce myopia. Some children respond differently than expected, and if that happens, the optometrist may suggest switching to another treatment to find what works best for your child.

Usually, myopia management treatment ends in late teens or when the level of myopia becomes stable. Some children may need to continue to have treatment, or may need to restart their treatment if their myopia starts to get worse again after treatment is stopped.

Considering myopia management

If you are considering myopia management for your child, it’s important to talk to your child’s optometrist about the advantages and disadvantages, based on your child’s age, lifestyle, and risk factors for myopia progression. If your optometrist doesn’t offer myopia management treatment, you can ask them to recommend an optician that does.

Myopia management usually continues until late teens. This means your child will need to attend regular check-ups to monitor progress and there may be adjustments to their treatment along the way. It’s also important to consider the ongoing costs of treatment and appointments as these are not covered by the NHS.

You may also need to think about whether your child is ready to start treatment. If considering contact lenses, readiness depends on maturity and good hygiene habits. Your child will need to be able to carefully use, clean and look after their contact lenses. Parents often worry about whether their child is too young when considering contact lenses, but evidence shows many children adapt well to them.

Further useful information can be found in The College of Optometrist’s leaflet myopia-and-myopia-management-v3.pdf.

If you choose not to have myopia management, your child will still be given regular glasses or contact lenses to make their vision clear. These won’t slow down the progression of myopia. Your child can choose other ways to correct their myopia as an adult, such as laser eye surgery or lens exchange (available privately). People with higher levels of myopia can have a slightly higher risk of certain eye conditions later in life compared to those without.

Living well

Most people who have myopia don’t have any complications and will only ever need glasses or contact lenses to correct their focusing error and make their vision sharper.

Children are eligible for an NHS optical voucher towards the cost of glasses or contact lenses. If you’re an adult and your prescription is -10.00D and over, then you would be eligible for an NHS complex lens voucher to use towards the cost of your glasses or contact lenses. Your optician will be able to tell you if your prescription is -10.00D or over and how much this voucher is worth.

It’s not possible to use an NHS optical voucher or complex lens voucher towards the cost of myopia management lenses. More information about NHS vouchers can be found at www.nhs.uk/nhs-services/opticians/nhs-voucher-values-for-glasses-and-lenses/