Hypermetropia

Long-sightedness, also known as hyperopia, affects a person's ability to see objects close to them.

Introduction

Long-sightedness, also known as hyperopia, affects a person's ability to see objects close to them.

Vision problems such as long-sightedness are often referred to as refractive errors.

If you are long-sighted, you will usually be able to see distant objects clearly, but nearby objects will be out of focus. Your eyes may also tire easily.

Read more about the symptoms of long-sightedness.

What causes long-sightedness?

Long-sightedness occurs when:

  • The eyeball is too short.
  • The cornea is not curved enough.
  • The lens is not thick enough.

The cornea is the transparent layer at the front of the eye, and the lens focuses light on to the retina (the light-sensitive layer at the back of the eye).

There are various causes of long-sightedness including age, genetics and certain underlying medical conditions, such as diabetes (where there is too much glucose in the blood).

Children are sometimes born long-sighted. The problem usually corrects itself as the child's eyes develop. However, it is important for children to have regular eyes tests because long-sightedness that does not correct itself can lead to other eye-related problems (see below).

Adults can also develop long-sightedness, which often becomes more noticeable after the age of 40. Age-related long-sightedness is known as presbyopia.

Read more about the causes of long-sightedness.

Diagnosing long-sightedness

Refractive errors, such as long-sightedness, are usually identified during early eye examinations.

Your child will have their eyesight checked regularly as part of the [routine screening programme]. However, you can have their eyes tested at any time if you are concerned about their vision.

Long-sightedness can usually be easily corrected, but if left untreated it could cause more serious complications that will affect your child's vision permanently (see below).

Treating long-sightedness

Long-sightedness is often corrected using either glasses or contact lenses.

Several surgical techniques have also been developed to treat the condition. Laser surgery is sometimes used although it is not suitable for everyone.

Read more about treating long-sightedness.

Complications of long-sightedness

In adults, complications of long-sightedness are rare. In children, severe hyperopia can cause them to "over-focus", leading to double vision. This in turn can lead to two possible eye-related conditions:

  • crossed eyes (strabismus), where the eyes are not properly aligned with each other and focus on different things
  • lazy eye (amblyopia), where one eye becomes dominant over the other

Read more about the complications of long-sightedness.

Symptoms

If you are long-sighted (hyperopia), this means you will be able to see distant objects clearly but objects near to you will be out of focus.

Adults

The eyesight of adults often deteriorates with age. Long-sightedness in adults (presbyopia) often becomes more noticeable after the age of 40.

If you develop long-sightedness, you may notice that:

  • Nearby objects are fuzzy and out of focus but distant objects are clear.
  • You have to squint to see clearly.
  • Your eyes may feel tired after activities that involve focusing on nearby objects, such as reading, writing or working on a computer.
  • You experience pain or burning in your eyes.

Children

Children who are long-sighted do not often have problems with their eyesight. The lenses in children's eyes tend to be more flexible than those of adults and are able to compensate for long-sightedness.

However, it is still important that young children have regular eyesight tests to check for conditions such as long-sightedness.

If left untreated, long-sightedness can lead to complications such as crossed eyes (strabismus) or lazy eye (amblyopia).

Read more about the complications of long-sightedness.

If your child is severely long-sighted, they may have problems with their eyes such as:

  • red or tearful eyes
  • squinting when looking at close objects
  • blinking and rubbing their eyes more than usual
  • reading problems

Read more about hearing and vision tests for children.

Causes

In long-sightedness (hyperopia), close objects appear blurred because the light that enters the eye is focused behind the retina.

However, it is not possible for light to be focused behind the retina so the lens tries to correct this refractive error by changing its thickness (it becomes fatter). This process is called accommodation.

If you are long-sighted, it is not possible to accommodate fully, which means light cannot be sharply focused and vision will be blurred. This may occur if the:

  • eyeball is too short
  • cornea is not curved enough (it's too flat)
  • lens is unable to become round enough

Long-sightedness can be caused by several factors which are described below.

Age

Long-sightedness can occur at any age, but it is often more noticeable after the age of 40.

Age-related long-sightedness is known as presbyopia. It develops when the lens in your eye becomes stiffer.

Genetics

Long-sightedness is thought to be a condition that some people inherit from their parents.

However, with the exception of a rare form of hyperopia called nanophthalmos, specific genes for long-sightedness have yet to be identified and further research is needed.

Underlying condition

In rare cases, long-sightedness can be caused by other, underlying conditions including:

  • diabetes
  • microphthalmia (small eye syndrome), where a baby’s eyes do not develop properly during pregnancy
  • tumours around the eye (orbital tumours)
  • foveal hypoplasia, where there is a problem with the blood vessels in the retina

Diagnosis

It is important for young children to have regular eye tests so that any problems are detected early on.

Most childhood eye conditions can be corrected, but left untreated could cause more serious problems that could affect your child's eyesight permanently.

Your child will have their eyesight checked several times as part of the [routine screening programme]. However, you can make an appointment for your child to have their eyes tested at any time if you are concerned about their vision.

It is also important for adults to visit their optician regularly.

Regular check-ups will help identify conditions such as long-sightedness at an early stage so that corrective treatment can be given.

Eye tests

Eye tests are carried out by an optometrist and usually take 20 to 30 minutes. During the test, your vision and the health of your eyes will be checked.

An eye test will usually include:

  • a check of your history and symptoms
  • an eye examination
  • a vision test

These are described below.

History and symptoms

The optometrist will start by asking whether you have any specific problems with your sight and, if so, how long you have had them for.

They may also ask you about your general level of health, including any medication you take and your lifestyle.

Eye examination

An optometrist will check that your eyes are healthy and that you do not have any underlying medical problems.

They will examine the inside of your eye using an opthalmoscope, which is a torch that shines light through your pupil. This also tests your pupil reflexes (whether your pupils shrink in response to light).

Your eye movements and co-ordination will also be checked to make sure both of your eyes are working together.

Other tests may also be carried out depending on your age and medical history. Eye conditions that your optician will be looking for include:

  • glaucoma (pressure changes in the eye that can damage the optic nerve)
  • diabetic retinopathy (where high blood pressure and high blood sugar cause new blood vessels to form in the eye which can obscure your vision)

Vision test

If you wear glasses or contact lenses, your vision will usually be tested both with and without them (so remember to take them with you).

The optometrist will usually assess your distance vision, your near vision (for reading and close work) and your intermediate vision (for using a computer).

A simple visual acuity test will help the optometrist assess how good your vision is. You may be asked to read from a Snellen chart, which is a series of letters that become progressively smaller on each line.

Your optometrist will then carry out further tests to determine the extent of your problem and the exact type of corrective lenses that you need.

After your eye test

After your eye test, the optometrist will discuss your results with you and the best course of action. This will usually be a prescription for glasses or contact lenses to correct any problems with your sight.

If your eyesight is okay, you will receive a statement to confirm that no correction is needed. If you need medical treatment, you may be referred to your doctor or hospital.

Read more about treating long-sightedness.

Children with long-sightedness who have a squint need to be monitored carefully to avoid a lazy eye developing.

Read more about the complications of long-sightedness.

Treatment

Long-sightedness (hyperopia) is often corrected with prescription glasses or contact lenses. In some cases, laser surgery is also an effective treatment option.

Glasses

Long-sightedness can usually be corrected with glasses made to your prescription. Convex lenses (thinner at the edge than at the centre) are used to correct long sight.

The curvature of the lens, its thickness and weight will depend on how severe your long-sightedness is. By wearing a lens made to your prescription, light rays will fall onto your retina, allowing you to focus accurately.

The lens of the eye becomes stiffer with age, so the strength of your prescription may need to be increased as you get older.

It is possible to be both long- and short-sighted. If this is the case, you may need to wear two different pairs of glasses. Alternatively, you could wear varifocal or bifocal lenses, which enable you to see objects clearly that are both near and far.

Contact lenses

Contact lenses can also be used to correct long-sightedness in the same way as glasses. Some people prefer contact lenses to glasses because they are lightweight and virtually invisible.

Contact lenses are available in many different materials and designs. Some lenses can be worn for a day and discarded (daily disposables). Others can be disinfected and re-used, or worn for longer periods and kept in overnight. Your optometrist can advise about the most suitable lens for you.

If you wear contact lenses, it is important you maintain good lens hygiene to prevent eye infections developing.

Surgical treatments

There are various surgical techniques to treat long-sightedness. The most reliable uses laser surgery.

Surgical treatment for long-sightedness involves increasing the curvature of the cornea to improve its focusing power by removing some tissue from the edge of the cornea.

The benefit of laser surgery compared with traditional surgery is that instruments do not have to enter the eye, which means that the risk of damage or infection is lower.

There are three main types of laser surgery:

Photorefractive keratectomy (PRK)

Photorefractive keratectomy (PRK) is where a small amount of the surface of the cornea is removed and a laser is used to remove tissue and change the shape of the cornea.

The removal of tissue is controlled by a computer, and the amount removed will depend on how poor your eyesight is. The surface of the cornea is then 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 removed.

As with PRK, a laser is used to change the shape of the cornea. The surface of the cornea is then put back and held in place by natural suction.

Laser in situ keratectomy (LASIK)

Laser in situ keratectomy (LASIK) is a similar procedure to LASEK, but only a small flap of the cornea is involved.

A small cutting instrument is used to cut a flap in the surface of the cornea which is then folded back rather than being 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 surgical procedure

Laser surgery is usually carried out on an outpatient basis. This means that you will not have to stay in hospital overnight, but will have one or more appointments at a clinic. The treatment usually takes 30-60 minutes.

LASIK is usually the preferred treatment option because it causes virtually no pain and your vision recovers quickly (within one-to-two days).

However, LASIK is a more complicated procedure and if complications do occur, they may be more serious.

Although your vision will recover quickly after having LASIK, you may experience some fluctuations in vision and it can take up to a month for your vision to stabilise completely.

LASIK treatment can only be carried out if your cornea is thick enough. If your cornea is too thin, the risk of complications and side effects, such as vision loss, is too great.

It may be possible for you to have LASEK or PRK if your cornea is not thick enough for LASIK surgery. The recovery time tends to be longer for these techniques – for example, it can take up to six months for your vision to fully stabilise after having PRK surgery.

The Royal College of Ophthalmologists provides more information about laser refractive surgery.

You should not have any sort of laser surgery if you are under 21 because your vision is still changing and it is dangerous to alter the structures of your eyes at this stage.

If you are over 21, changes to your vision can still occur. Before having laser treatment, your clinic should check your glasses or contact lens prescriptions to confirm that your vision has not changed significantly over the last two years.

Laser surgery may also not be suitable if you:

  • have diabetes – it 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 HIV or rheumatoid arthritis; this may affect your ability to recover after surgery
  • have other problems with your eyes - such as glaucoma (a condition that causes pressure changes in the eye and can cause blindness) and cataracts (where the lenses harden and become cloudy)

Risks of laser surgery

As with all types of surgery, laser surgery carries some risks and you should discuss these with your surgeon before deciding to have the procedure.

Some possible complications of laser surgery are:

  • Following surgery, your vision may be worse if the surgeon misjudges the amount of tissue taken from your cornea (this is known as a correction error).
  • The flap cut into your cornea may start to grow into the main part of your cornea when it is replaced (this is known as epithelial in-growth and it can cause vision problems which may require further surgery to correct).
  • Your cornea can become too thin, leading to a reduction in vision or a loss of vision (this is called ectasia).
  • Your cornea can become infected (known as microbial keratitis).

It is important to note the above risks are rare.

Complications

Adults rarely have complications as a result of long-sightedness (hyperopia). In children, severe hyperopia can cause them to "over-focus", leading to double vision and two other eye conditions.

Long-sightedness in adults (presbyopia) is likely to get worse with age. However, a prescription for stronger glasses or contact lenses will enable most people to retain normal vision.

In children, severe long-sightedness can cause them to "over-focus" and experience double vision. This can lead to one eye turning away, resulting in crossed eyes or lazy eye.

Crossed eyes (strabismus)

Crossed eyes (strabismus) are where the eyes are not properly aligned with each other, so they both focus on different things.

It can lead to problems judging how far away objects are from you (depth perception). It can also cause your brain to ignore the output of one eye, which can weaken the eye and lead to lazy eye (see below).

Lazy eye (amblyopia)

Lazy eye (amblyopia) is where one eye becomes dominant over the other, either as a result of strabismus or another eye condition, such as cataracts (these are cloudy patches in the lens of the eye).

If a child only uses one eye to focus, their other eye will get weaker and weaker. If left untreated, the weaker eye could eventually lose all of its vision.

Read more about lazy eye.

Treating strabismus and amblyopia

Strabismus and ambylopia can usually be treated by making the child wear a patch over their stronger eye. This forces their brain to start using the weaker eye, making it stronger.

Glasses can also be prescribed to help balance the vision of both eyes. In more severe cases, surgery may be needed to realign or strengthen the muscles of the eye.

Content supplied by NHS Choices