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Short-sightedness

Key points

  • If you’re short-sighted, it means you can't see distant objects clearly.
  • To diagnose short-sightedness you’ll be asked to read a chart that has large letters at the top and small letters at the bottom.
  • Short-sightedness is usually corrected by wearing glasses or contact lenses; surgery may also be an option.

Short-sightedness, known medically as myopia, is a common vision problem. If you’re short-sighted, you won’t be able to focus on distant objects, but will be able to see close objects clearly. Another name for short-sightedness is near-sightedness.

About short-sightedness

When you look at an object, light rays from the object pass into your eye through the cornea. This is the clear structure at the front of your eye. The light rays then pass through your lens and are focused onto the retina at the back of your eye. In a healthy eye, your cornea focuses the light towards your retina and your lens ‘fine tunes’ this.

If you’re short-sighted, it means you can’t focus clearly on distant objects. This may be because your cornea is too curved or your eyeball is too long (or both). This makes it more difficult for your eyes to focus light rays directly on your retina – they are focused in front of your retina instead. If the light rays aren’t clearly focused on your retina, the object you’re looking at will seem blurred.

Objects that are close to you won’t look blurry. This is because the point at which light is focused at this distance moves back into focus on the retina. The near object is therefore clear.

Illustration showing the changes that occur if you are short-sighted

Short-sightedness is very common – it affects about one in four adults in the UK. It usually starts to develop in teenagers or young adults.

Short-sightedness is measured in numbers called dioptres. A dioptre (D) is a measurement of the strength of a spherical lens and is used to grade the severity of short-sightedness. A minus sign is added to prescriptions to show what lens you need to correct short-sightedness. The higher the number, the more short-sighted you are.

  • 0 to -3D is mild short-sightedness.
  • -3D to -6D is moderate.
  • -6D or more is high degree short-sightedness.

Symptoms of short-sightedness

If you’re short-sighted, you can see close objects clearly, but distant objects will appear blurred. You may find that you narrow your eyes – or squint – to make far away objects seem clearer. This can give you headaches.

Young children may not realise they have blurred vision. Signs that your child may be short-sighted include:

  • squinting (narrowing their eyes)
  • frowning
  • rubbing their eyes or blinking a lot
  • sitting close to the TV
  • having trouble seeing the whiteboard at school

Short-sightedness progresses until the eyes stop growing at around the age of 20. The severity of short-sightedness then usually levels off but it can also get worse as you get older.

Causes of short-sightedness

The exact reasons why you may develop short-sightedness aren’t fully understood at present. However, it’s more likely if you:

  • were born prematurely
  • have parents who are short-sighted
  • read a lot or do lots of close-up work, such as sewing or using a computer
  • have another health condition that can affect your eyes, such as Marfan’s syndrome or homocystinuria

Some research suggests that children who spend less time outdoors may be more likely to develop short-sightedness too.

Diagnosis of short-sightedness

If you’re struggling to see things in the distance, book an appointment with an optometrist to have your eyes tested. An optometrist is a registered health professional who examines eyes, tests sight and dispenses glasses and contact lenses.

To diagnose short-sightedness, your optometrist will ask you to read a chart (called a Snellen chart) from a distance of six metres. The chart has large letters at the top and small letters at the bottom. If you're short-sighted, you won't be able to read the smaller letters on the chart.

Children can have an eye test using different sized pictures instead of letters.

It’s important to have regular eye tests to diagnose any problems with your sight. Your optometrist will also look for any problems with your general health, such as diabetes, that can be picked up by examining your eyes. Most people should have an eye examination every two years, even if they don’t have any problems with their sight. Ask your optometrist how often you need one.

You may need to have eye examinations more often as you get older or if you have a:

  • condition that may affect your sight, such as diabetes or glaucoma
  • close relative who has a condition that may affect his or her sight, such as diabetes or glaucoma

Eye examinations are usually quick and painless and, for some people, they are free. Ask your optometrist for more information.

Treatment of short-sightedness

Glasses and contact lenses

Short-sightedness can usually be corrected by wearing glasses or contact lenses. Concave lenses – in glasses or contact lenses – will help focus light more precisely on the retina so that you can see distant objects.

Children or teenagers who develop short-sightedness may need to change their glasses or contact lenses often. This may be every six months to a year until their short-sightedness stops changing.

If you’re mildly short-sighted, you may only need to wear glasses or contact lenses occasionally, such as when you’re driving or watching TV.

If you have contact lenses, you will need to keep them clean and some types need to be cared for in a particular way. A popular type of contact lens is daily disposables which you wear for one day and then throw away. You don’t need to clean or store these lenses.

Glasses are usually recommended for children. They can also be more suitable than contact lenses for older people. Your optometrist will discuss with you what options are available.

Surgery

There are a number of operations to correct short-sightedness. Some of these are listed below.

Laser refractive surgery
In laser refractive surgery, your surgeon will make small alterations to your cornea using a laser, so that light rays focus correctly onto your retina. To treat short-sightedness, he or she will make the centre of your cornea flatter by removing more tissue from the centre than from the edge.

Laser eye surgery works very well for most people. However, there is a chance you won’t get the improvement in your eyesight that you expect and so may need further treatment.

There are different types of laser refractive surgery and there are some general risks associated with them. These include:

  • a return of some of your short-sightedness after time
  • an infection in your cornea
  • symptoms of a dry eye
  • distorted vision
  • problems with the flap that is made in your cornea during certain types of laser eye surgery

If you choose to have laser refractive surgery, it’s important that you consider the benefits and risks of the operation before you go ahead. You should also make sure that it’s carried out by a trained ophthalmologist. This is a doctor who specialises in eye health, including eye surgery. Ask your optometrist or GP for advice about finding an ophthalmologist.

Laser refractive surgery isn’t suitable for everyone. Your ophthalmologist will discuss with you whether it’s an option for you.

Intraocular lens implant
An intraocular lens implant is an artificial lens that is placed inside your eye. It takes over the role of your natural lens.

There are two main types of lens implant. There are those where you keep the natural lens of your eye. This is called a ‘phakic’ contact lens implant or implantable contact lens (ICL). The other type involves replacing the natural lens of your eye with an intraocular lens in an operation.

If you’re severely short-sighted, some types of laser refractive surgery may not be suitable and phakic ICLs may be a better option. Laser surgery is permanent and can’t be reversed, but it’s possible to remove or replace a phakic ICL.

Intracorneal rings
Another treatment for short-sightedness is intracorneal rings, which are designed to flatten your cornea. This is a relatively new procedure and the possible complications are not yet fully known.

Radial keratotomy
In this operation, your surgeon makes several tiny cuts in your cornea to flatten it and make light rays fall more precisely on your retina. This is an older treatment and it has largely been replaced by laser surgery.


Reviewed by Rachael Mayfield-Blake, Bupa Health Information Team, March 2014.

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  • This information was published by Bupa's Health Information Team and is based on reputable sources of medical evidence. It has been reviewed by appropriate medical or clinical professionals. Photos are only for illustrative purposes and do not reflect every presentation of a condition. The content is intended only for general information and does not replace the need for personal advice from a qualified health professional. For more details on how we produce our content and its sources, visit the about our health information page.

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