Hyperopia - longsightedness
Hyperopia is the medical name for long-sightedness, which is characterised by difficulty seeing objects up-close. Most people who have hyperopia can see things in the distance clearly, but when they look at things up-close they are blurred and out of focus. Hyperopia is the opposite of myopia, which is short-sightedness and means that people have trouble seeing things far away. Hyperopia tends to be more common in people over the age of 40, though it can affect all ages; age-related hyperopia is known as presbyopia.
It is possible for children to be born with hyperopia. In many cases the child’s sight improves as they get older, but regular eye tests will be recommended because, if hyperopia is not treated in children, it can cause a squint (known as strabismus) or a lazy eye (known as amblyopia).
What causes hyperopia?
There are various factors that can cause hyperopia, including:
- The eyeball being abnormally short.
- The cornea not being sufficiently curved.
- The lens being too thin.
These factors all prevent light rays from being focused properly on the retina, which makes objects appear blurred. Hyperopia is often inherited and many people who are diagnosed have parents or siblings with the condition. However, no specific gene has been found for long-sightedness.
In rare cases underlying health conditions can cause hyperopia, including:
- Tumours around the eye.
- Small eye syndrome (also known as microphthalmia).
- Foveal hypoplasia.
Symptoms of hyperopia
Symptoms of hyperopia in adults include:
- Objects and images close-by appear blurred, while those in the distance appear clear.
- Squinting to see things more clearly.
- Pain or a burning sensation.
- Your eyes may feel strained after reading, typing or watching television.
Symptoms of hyperopia in children
Many children do not experience any symptoms as the lenses in their eyes are more adaptable. However, doctors advise parents take their child for regular eye tests to ensure that their eyesight can be monitored closely and treatment arranged if necessary. If a child has severe hyperopia the following symptoms may present:
- Red, sore eyes.
- Difficulty reading.
- Blinking and rubbing their eyes.
How is hyperopia diagnosed?
It is important for children to have regular eye-tests and ideally a child’s eyes should be tested every 12 months. The NHS provides routine eye tests for children at birth, at the age of 3 and just before the child starts school, but free eye tests are accessible for children on the NHS up to the age of 16.
Adults should also have regular eye tests. You should arrange to have an eye examination if you experience any of the symptoms listed above or if you find you are struggling to see things close-up or in the distance. Most cases of long- and short-sightedness can be corrected fairly easily, but the conditions can become worse if they are left untreated.
During an eye test the optometrist will examine the eye, check your sight and take details of your medical history. If you have been experiencing symptoms you will also be asked about this.
The inside of the eye is examined using an instrument called an ophthalmoscope and your vision will be tested using a Snellen chart; a chart with lots of letters of different sizes. If you wear contact lenses or glasses take these with you to your appointment, as the optometrist will test your sight with and without them.
In most cases hyperopia is treated by correcting your eye sight using glasses or contact lenses.
Glasses are made to fit your individual prescription and long sightedness is usually corrected using convex lenses. If you wear glasses you will be advised to have regular eye tests to check that your glasses are still working properly, as many people find that their prescription changes as they get older and they require new lenses. There is a huge variety of frames to choose from and you can also buy prescription sunglasses.
Contact lenses work in a similar way to glasses. They are very small lenses that fit in the eye and many individuals choose to wear contact lenses because they are invisible to others. Two categories of contact lens are available: rigid glass permeable lenses and soft lenses. You can chose from daily contacts which are thrown away at the end of the day or lenses that you can wear for a long time. If you choose the latter you have to clean your lenses at the end of each day to prevent infection.
In recent years laser eye surgery has become popular with people deciding to have long-term treatment. Laser eye surgery is not suitable for everyone but the results are usually very successful and it is generally considered to be a very safe procedure. You will need to attend a consultation with an ophthalmologist before you have surgery to check that you are suitable for treatment.
There are three main categories of laser eye surgery for long-sightedness. These include:
- PRK (photorefractive keratectomy): this procedure involves removing a small sum of the cornea’s surface and using laser beams to re-shape the cornea and remove a small amount of corneal tissue.
- LASIK (laser in situ keratectomy): this procedure involves a small incision in the cornea and lifting a flap to access the rest of the cornea. The laser is used to change the shape of the cornea and the flap is then folded back to its original position.
- LASEK (laser epithelial keratomileusis): this procedure works in a similar way to PRK but uses alcohol to make the cornea’s surface looser before it is removed.
Laser eye treatments are relatively painless and quick. Most experts prefer to use LASIK as recovery time is much quicker. However, this method is not suitable for everyone and will not be carried out if the cornea is thin.
Laser eye surgery is generally not recommended for the following:
- People under the age of 21 (this is because the prescription is likely to change).
- Pregnant women.
- People with diabetes.
- People with conditions that weaken the immune system, such as HIV.
- People who have other eye conditions.
Possible risks of laser eye surgery include:
- Corneal infection.
- Ectasia (when the cornea becomes thinner, causing loss of sight).
- Vision deteriorating as a result of the surgeon removing too much corneal tissue.