Short-sightedness is a common eye condition that causes distant objects to appear blurred, while close objects can be seen clearly.
It's thought to affect up to one in three people in the UK and is becoming more common.
The medical term for short-sightedness is myopia.
Cases of short-sightedness can range from mild, where treatment may not be required, to severe, where a person's vision is significantly affected.
The symptoms of short-sightedness often start around puberty and gradually get worse until the eye is fully grown.
If distant objects appear fuzzy to you or if your child is finding it difficult to see things in the distance, such as the blackboard at school, you should make an appointment for a sight test with an optometrist (optician).
What causes short-sightedness?
Short-sightedness is a refractive eye condition. Refractive eye conditions occur when problems with the eye's structure affect how light enters the eye.
Most people are born slightly long-sighted (hyperopia), where close objects appear blurred. This is because at birth the eyes have not grown to their full length.
Children are able to "accommodate", which means they can overcome the long-sightedness. After the eyes have grown to their full length (by around eight years of age), the sight is normal. This is known as emmetropia.
However, in short-sightedness, the eyes keep growing and become too long from front to back. This means that light doesn't reach the light-sensitive tissue (retina) at the back of the eye. Instead, the light rays focus in front of the retina, resulting in distant objects appearing blurred. Unlike long-sightedness, it isn't possible to overcome short-sightedness.
Short-sightedness is usually caused by a combination of genetic and environmental factors that disrupt the eye's normal growth.
Short-sightedness is usually diagnosed by an optician during an eye test.
A simple test will be used to help assess your vision. You may be asked to read from a chart that has rows of letters that get smaller on each line.
If you have problems reading the letters at a distance that most people can read easily, it is likely that you are short-sighted.
Short-sightedness can be treated in three ways:
- using corrective lenses such as glasses or contact lenses to compensate for the structural defects in the eye
- using laser surgery to correct the defect (children cannot have laser surgery because their eyes are still developing) – most people have to pay for private laser surgery
- implanting an artificial lens into the eye to compensate for the longer eye length in people who are severely short-sighted
Associated eye conditions
If you have severe short-sightedness (high degree myopia), you are more likely to develop other eye disorders in later life. These might include:
- retinal detachment – where the retina pulls away from the blood vessels that supply it with oxygen and nutrients
- glaucoma – where high eye pressure damages the optic nerve at the back of the eye
- cataracts – where cloudy patches develop inside the lens of the eye
- macular degeneration – where the central section of the retina (the macular) becomes damaged, leading to some loss of central vision
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Signs and symptoms of short-sightedness
The main symptom of short-sightedness (myopia) is distant objects appearing blurred, while near objects can still be seen clearly.
When does short-sightedness occur?
Short-sightedness usually starts to develop around puberty, but it can develop at any age, including in very young children.
It's unusual for the condition to start after the age of 30, although older people may become short-sighted as a result of cataracts (cloudy patches that develop in the lens of the eye).
Younger children may think that blurred vision is normal, so their symptoms may only be noticed after they start school and have difficulty reading the blackboard.
Short-sightedness often gradually gets worse as a child gets older. This is because as the child grows, their eyes grow longer. The condition tends to stabilise after a person is fully grown, although sometimes it can progress until the mid- to late-20s.
In older people, the onset of short-sightedness can be an early indication that a cataract is forming. Cataracts occur when the eye's lens, which is usually clear, starts to become opaque (cloudy), resulting in blurred or cloudy vision. They are usually associated with ageing.
If you or your child notice the signs of short-sightedness, you should make an appointment for a sight test with an optometrist (optician).
Severity of short-sightedness
Healthcare professionals use a measurement called dioptres (D) to describe how severely short-sighted a person is. The higher the measurement, the longer a person's eye or the more curved their cornea (the transparent layer at the front of the eye).
For short-sightedness, dioptres are written as a negative measurement (-3D), whereas in long-sightedness they are written as a positive measurement (+3D).
There are three classifications used to describe the severity of short-sightedness. These are outlined below.
Mild myopia is a measurement of -0.5D to -3D. This is the most common type of short-sightedness. You may be able to manage without wearing glasses or contact lenses, but they may be recommended for certain activities, such as driving or watching television.
Moderate myopia is a measurement of -3D to -6D. If you have moderate myopia, it is likely that you will have to wear glasses or lenses all the time.
High myopia is a measurement of more than -6D. If you have high myopia, you will only be able to see objects clearly without glasses if you hold them very close to your eye.
Causes of short-sightedness
The exact cause of short-sightedness (myopia) is unknown, but it's thought to be the result of a combination of genetic and environmental factors that disrupt the normal development of the eye.
How the eye works
Light passes through the cornea and into the lens, where it is focused onto the retina at the back of the eye to create an image. The image is converted into an electrical signal, which is transmitted to the brain via the optic nerve.
To produce a perfectly clear image, the cornea should be smooth and evenly curved, and the eye needs to be the right length. However, in most cases of short-sightedness the eye has grown too long. In a few people, the cornea may be more curved than normal.
These structural deformities mean that when you look at distant objects, the light is not focused directly onto your retina but a short distance in front of it. This results in the image that is sent to your brain being blurred.
Inheriting short sight
Short-sightedness is known to run in families. Children with one short-sighted parent have a greater risk of developing myopia of about a one in three chance. If both parents are short-sighted, the risk increases further to one in two.
Genetic research has identified 26 genes linked to short-sightedness. These are responsible for the eye's structure and development and signalling between the brain and the eye.
Environmental factors, such as reading, writing and using a computer, can increase your risk of developing short-sightedness.
One study found that children who read for 30 minutes or more each day were one-and-a-half times more likely to develop myopia than children who didn't read for this period of time.
Research has also shown that children who spend time doing outdoor activities, such as playing sports, are less likely to become short-sighted and existing short-sightedness may progress less quickly.
It is thought that this protective effect could be associated with the higher light levels outside than inside, and the fact that you are not constantly focusing on near objects.
An "everything in moderation" approach is recommended. Although children should be encouraged to read, they should also spend some time away from reading and computer games each day doing outdoor activities.
Research is currently underway to investigate how environmental factors affect the genes linked with short-sightedness.
At the moment, glasses and contact lenses are the main treatments for short-sightedness. However, now more is understood about the role genetics plays in the condition, it may be possible to develop new treatments to correct the condition or prevent it getting worse.
Most cases of short-sightedness (myopia) are diagnosed by an optician during an eye test.
Opticians are healthcare professionals who specialise in diagnosing common eye conditions, such as short-sightedness. They also prescribe corrective lenses.
During an eye test, your optician will test your vision with and without your glasses or contact lenses (if you wear them).
They will usually assess your distance vision, your near vision (for close work, such as reading) and your intermediate vision (for using a computer).
The optician will use a simple visual acuity test to assess how good your vision is. You may be asked to read from a chart that has a number of rows of letters that get smaller on each line.
If you have problems reading the letters at a distance that most people can read easily, it's likely that you'll be diagnosed with short-sightedness.
Your optician may refer your child to the hospital eye service. This may be because young children are more difficult to test, or because the optician would like an ophthalmologist or an orthoptist to carry out an assessment.
Ophthalmologists are doctors who specialise in diagnosing and treating eye conditions. Orthoptists are experts in checking children's vision and the balance of the eye muscles.
To measure how severe your short-sightedness is, your optician will use a test called retinoscopy, where a bright light is shone in your eye to see how your retina reacts.
You may also be asked to look at a chart through a series of different strength lenses to see how they affect your vision. This will help the optician to determine the strength your prescription should be.
Free eye tests
For some people, eye tests are available free of charge on the . You qualify for a free -funded eye test if you are:
- aged under 16, or aged under 19 and in full-time education
- aged 60 or over
- registered blind or partially sighted
- diagnosed with diabetes or glaucoma
- aged 40 or over and you are the parent, brother, sister, son or daughter of a person diagnosed with glaucoma, or you have been advised by an ophthalmologist that you are at risk of glaucoma
- eligible for an complex lens voucher
You are also entitled to a free sight test if:
- you receive Income Support or income-based Jobseeker's Allowance (not contribution-based)
- you receive Pension Credit Guarantee Credit
- you receive income-based Employment and Support Allowance
- you are awarded Universal Credit
- you are entitled to, or named on, a valid tax credit exemption certificate
- you are named on a valid certificate for full help with health costs (HC2)
People named on an certificate for partial help with health costs (HC3) may also get help.
Glasses or contact lenses are the most common method of correcting short-sightedness (myopia). Laser surgery is also becoming increasingly popular.
Implanting artificial lenses in the eyes is a fairly new technique that can be used if laser surgery is ineffective or not possible.
Short-sightedness can usually be corrected using glasses made specifically to your prescription.
Concave lenses are used that are thicker at the edge than at the centre. The curvature of the lens, its thickness and weight will depend on how short-sighted you are.
Wearing a lens that is made to your prescription will ensure that light rays fall onto your retina and you can focus accurately.
The lens of the eye becomes less flexible as you get older, which means you may need to use two pairs of glasses, with one pair for close vision activities such as reading and the other pair for distance vision activities such as watching television.
Some people prefer to use bifocal lenses that allow them to see objects clearly that are both close up and far away without changing their glasses.
You can also get multifocal lenses that help you see nearby objects and those at intermediate and long distances. Monovision is another option, where one lens is set for distance and the other is set for close work.
Contact lenses can also be used to correct vision in the same way as glasses. Many people prefer contact lenses to glasses because they are lightweight and almost invisible.
There are two types of contact lenses – rigid gas-permeable contact lenses and soft contact lenses. However, there are many different lens materials and designs.
Contact lenses can be worn on a daily basis and discarded each day (daily disposables), or they can be disinfected and reused. They can also be worn for a longer period of time. However, eye specialists generally recommend that contact lenses are not worn overnight because of the risk of infection.
Some opticians occasionally use a technique called orthokeratology. It involves wearing a hard contact lens overnight to flatten the curvature of the cornea so that you can see better without a lens or glasses during the day.
It is not a cure for short-sightedness because the cornea usually returns to its normal shape, but it can reduce reliance on lenses for mild or moderately short-sighted people.
Your optician will be able to advise you about the most suitable type of contact lenses for you. If you decide to wear contact lenses, it is very important that you maintain good lens hygiene to prevent eye infections.
Availability on the
You can get vouchers towards the cost of glasses or contact lenses if you're eligible – for example, if you are under 16 years of age or if you are receiving Income Support.
If you are not eligible, you'll have to pay for glasses or contact lenses. The cost of glasses can vary significantly depending on your choice of frame. Entry-level glasses start at around £50, with designer glasses costing several hundred pounds.
The cost of contact lenses will vary depending on your prescription and the type of lens you choose, but they typically cost £30-50 a month.
Laser surgery involves using a laser to burn away small sections of your cornea to correct the curvature so light is less tightly focused through your lens and on to your retina.
There are three main types of laser surgery, which are briefly outlined below.
Photorefractive keratectomy (PRK)
In photorefractive keratectomy (PRK), a small amount of the cornea's surface is removed and a laser is used to remove tissue and change the shape of the cornea.
The amount of tissue removed is controlled by a computer and will depend on how poor your eyesight is. After the procedure, the surface of the cornea is left to heal.
Laser epithelial keratomileusis (LASEK)
Laser epithelial keratomileusis (LASEK) is a similar procedure to PRK, but involves using alcohol to loosen the surface of the cornea before it is lifted out of the way.
As with PRK, a laser is then used to change the shape of the cornea. Once the treatment is finished, the surface of the cornea is replaced and is held in place by natural suction.
Laser in situ keratectomy (LASIK)
Laser in situ keratectomy (LASIK) is similar to LASEK, but only a small flap of the cornea is involved.
A surgical instrument is used to cut a flap in the surface of the cornea, which is then folded back rather than removed. A laser is used to change the shape of the cornea, after which the flap is folded back down to its original position and held in place by natural suction.
The laser surgery operation
Laser surgery is usually carried out on an outpatient basis, so you will not have to stay in hospital overnight. You will need to have one or more appointments at a clinic. The treatment usually takes 30 minutes to an hour.
LASEK or LASIK are usually the preferred methods as they cause almost no pain and your vision will recover within one to two days. However, you may experience some fluctuations in your vision after this. It can take up to a month for your vision to stabilise completely and for you to feel the full benefits of the operation.
Laser treatment can only be carried out if your cornea is thick enough. If your cornea is thin, the risk of complications and side effects occurring, such as loss of vision, is too great.
LASEK and PRK may be possible if your cornea is not thick enough for LASIK surgery. However, the recovery time tends to be longer using these techniques – it can take up to six months for your vision to stabilise after having PRK surgery.
The Royal College of Ophthalmologists has published a Patient's Guide to Refractive Laser Surgery and also provides answers tospecific questions related to laser refractive surgery.
You can also read NICE guidance about laser surgery for the correction of refractive errors (PDF, 75.3kb).
The results of all three techniques are usually good. While it may not always be possible to completely cure your short-sightedness, around 9 out of 10 people experience a significant improvement in their symptoms.
Most people who have laser surgery report that they are happy with the results. However, it is important to realise that laser surgery may not necessarily improve your vision to the same degree as wearing corrective lenses. Also, as with any type of surgery, laser surgery carries the risk of complications.
Complications of laser surgery
Laser surgery does carry risks, with dry eyes after the procedure being the most common complication.
Dry eyes can occur if the lasers damage the nerves that stimulate tear production. The nerves will grow back after about six months. During this time, you can lubricate your eyes with eye drops to help lessen the dryness and any irritation.
Other complications include:
- removal of too much cornea tissue – this could leave you with an eye that is long-sighted and occurs in around 1 in 20 cases
- reduced night vision – this usually passes within six weeks
- a haze effect around bright lights – this will usually pass within 6 to 12 months
More serious complications of laser surgery are much rarer and include:
- epithelial in-growth – where the flap that is cut into your cornea begins to grow into the main part of the cornea when it is replaced; this can cause problems with your vision and further surgery may be required to correct it
- ectasia – where the cornea becomes too thin and your vision is reduced or lost
- microbial keratitis – where the cornea becomes infected
Who cannot have laser surgery?
You should not have any sort of laser surgery if you are under the age of 21. This is because your vision is still developing and it would be dangerous to alter the structure of your eyes at this stage.
Your vision can also change if you are over 21. Your clinic should check your glasses or contact lens prescriptions to confirm that your vision has not changed significantly over the last two years.
You may also not be suited to laser surgery if you:
- have diabetes – this can cause abnormalities in the eyes that can be made worse by laser surgery to the cornea
- are pregnant or breastfeeding – your body will contain hormones that cause slight fluctuations in your eyesight and focusing power, making precise surgery too difficult
- have a condition that affects your immune system, such as HIVor rheumatoid arthritis – these types of conditions may affect your ability to recover after surgery
- have other problems with your eyes, such as glaucoma (where increased pressure in the eye can lead to vision loss), or cataracts(where cloudy patches develop in lens of the eye)
Laser surgery isn't usually available on the because other treatments, such as glasses or contact lenses, are considered to be equally – if not more – effective. You will therefore usually have to pay for surgery privately.
Prices can vary depending on where you live in the country, the individual clinic and the type of equipment used during the procedure. However, as a rough estimate you usually have to pay somewhere around £800-1,500 for each eye.
Lens implant surgery
Lens implant surgery is a relatively new type of surgery for short-sightedness. It involves implanting an artificial lens into your eye.
The artificial lens is specially designed to compensate for any defects in the cornea so that rays of light are focused more clearly on to the retina.
There are two main ways of performing lens implant surgery. They are:
- inserting a phakic implant, which is a contact lens that's permanently inserted into your eye without removing your natural lens ("phakic" means that the eye contains its natural lens)
- replacing the natural lens with an artificial one, which is sometimes known as refractive lens exchange
These two types of lens implant surgery are described in more detail below.
Phakic lens implant
Phakic lens implants are generally used for people between the ages of 25 and 45 who are not suitable candidates for laser surgery – for example, people with severe myopia or those who have difficulty wearing glasses.
Phakic lens implantation is the preferred technique for younger people (those under 45) because their natural unaided reading vision is preserved.
The procedure is carried out using a local anaesthetic and you will be able to return home the same day. Your pupil is dilated using eye drops and a phakic lens implant is inserted into your eye through a small cut in the cornea.
Depending on its design, the phakic lens will be attached to your iris (the coloured part of the eye), placed in the angle between your cornea and iris, or positioned so that it floats over the surface of your natural lens.
As with laser surgery, lens implant surgery is not usually available on the. Both types of surgery can be quite expensive, with many clinics quoting prices of around £4,000-5,000 for treating both eyes.
Reducing the progression of short-sightedness in children
It can be worrying when your child's short-sightedness gets worse as they grow. There are no 100% proven treatments yet that can stop this happening, but the most effective treatment is probably an eye drop called Atropine 1%.
However, this has significant side effects, such as dilating the pupil and making your child sensitive to light, or blurring reading vision, resulting in the need for bifocal or multifocal (varifocal) glasses.
Research is currently being carried out to look at more dilute Atropine eye drops, specialised contact lens designs (multifocal contact lenses) and orthokeratology (gas-permeable contact lenses that temporarily reshape the cornea to reduce refractive errors).
However, these treatments won't become available until their safety and effectiveness has been thoroughly assessed and confirmed.
Eye conditions associated with short-sightedness
If you have severe short-sightedness (high degree myopia), you are more likely to develop other eye disorders later in life.
For example, you may also have:
- retinal detachment
- macular degeneration
These are described below.
If you are short-sighted, your risk of developing glaucoma is increased. This is where increased pressure inside your eye can lead to a loss of peripheral vision (the outer edge of your field of vision).
Glaucoma develops very slowly and has no noticeable symptoms in the early stages. You should therefore have regular eye tests to help identify problems at an early stage. This is particularly important for people who are over 40 years of age.
Cataracts are cloudy patches that develop in the lens of the eye, making your vision blurred or misty. They can develop in one or both eyes, with one eye often more affected than the other.
Over time, the cloudy patches become bigger and more of them develop. As less light is able to pass through the lens, your vision will become blurry or cloudy. The cloudier the lens becomes, the more your vision will be affected.
If you are short-sighted, your chances of developing retinal detachment are also increased.
This is where the light-sensitive lining at the back of the eye (retina) starts to peel away from the deeper layers of eye tissue. If left untreated, retinal detachment can cause permanent vision loss.
In cases of severe short-sightedness, the central part of the retina (macula) can become damaged. This is known as macular degeneration and it can lead to permanent poor vision for reading and close work. It usually develops in older age.