For some people, including children under 16 and those over 60, eye tests are available free of charge on the NHS. Find out more about free NHS eye tests to check if you qualify. Find out more about diagnosing long-sightedness. Long-sightedness is when the eye does not focus light on the retina the light-sensitive layer at the back of the eye properly. It's often not clear what causes these problems, but they're rarely a sign of any underlying condition. Sometimes long-sightedness may be a result of the genes you inherited from your parents, or a result of the lenses in your eyes becoming stiffer and less able to focus as you get older.
Children and young adults with long-sightedness may not need any treatment, as their eyes are often able to adapt to the problem and their vision may not be significantly affected.
Treatment is usually required in older adults, particularly those over 40, as your eyes become less able to adapt as you get older.
Glasses are the simplest and safest treatment. Contact lenses and laser eye surgery carry a small risk of complications and are not usually suitable for young children. Other tests may also be carried out depending on your age and medical history. Eye conditions that your optician will be looking for include:. 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, 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. Children with long-sightedness who have a squint need to be monitored carefully to avoid a lazy eye developing. Long-sightedness hyperopia is often corrected with prescription glasses or contact lenses. In some cases, laser surgery is also an effective treatment option. 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 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. 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. 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 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. 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. 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 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. 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.
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. 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.
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 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. For looking at far objects, the ciliary muscle relaxes, making the suspensory ligaments tighten, and the lens thins out. More bending refraction of the light rays is needed to focus on nearby objects, such as when reading.
Less bending of light is needed to focus on objects far away. Long sight occurs when light from near objects is not quite brought to focus in time to hit the retina. The point of focus would in fact be behind the retina, if the light could get that far.
The lens tries hard to change its thickness becomes fatter or more rounded in an attempt to bring the light into focus on the retina - a process called accommodation. However, people with long sight cannot accommodate fully and so the light does not focus on the retina and vision is blurred. This occurs because the eyeball is too short, the cornea is too flat and so bends the light rays less , or the lens cannot become round enough and so lacks power.
People with a minor degree of long sight can usually see at distance, as this light does not require the same strength of focusing. Their near sight may also be clear. However, they may get tiring of the eyes, often with a headache and vision discomfort, because the lens is having to work so hard. People with more severe hypermetropia are not able to see near objects clearly in focus.
Long sight means exactly what the term suggests: you can see objects which are a long distance from you quite clearly. The diagram above shows the differences in focusing between a normal and a long-sighted hypermetropic eye:. The causes of long sight are usually hereditary genetic. Long sight can occur at any age but it tends to become more noticeable above the age of 40 years.
In rare cases, long sight is caused by other conditions such as diabetes, small eye syndrome microphthalmia , cancers around the eye and problems with the blood vessels in the retina. Many babies and very young children tend to be slightly long-sighted but usually grow out of this by about 3 years of age.
A particular type of age-related long sight presbyopia occurs because the lens of the eye becomes more stiff with age. See the separate leaflet called Age-related Long Sight Presbyopia for more details. The main symptom is a difficulty with near vision. There may be difficulties with seeing with both eyes binocular vision , as the brain will tend to ignore signals coming from the most long-sighted eye. Lazy eye amblyopia or squint strabismus can therefore also occur in long sight.
Long-sighted people may have difficulty with depth perception 3-dimensional vision , as this needs two eyes to work together, more or less equally.
If severe long sight hypermetropia is present from a very young age, lazy eye amblyopia can result. The eye with less good vision does not learn to see properly because the brain ignores its signals and concentrates only on the better eye.
Visual development in the brain occurs in the first few years of life and if this problem is not spotted until after vision has finished developing, the poorer eye will not fully develop its 'information route' into the brain, so will never see as well.
See the separate leaflets called Amblyopia and Squint Strabismus in Children for more details. The simplest, cheapest and safest way to correct long sight is with glasses.
Convex prescription lenses called plus lenses are used to bend light rays slightly inwards to give a little bit of additional focusing power to the eye. The light rays then have a lesser angle to bend travelling through the cornea and lens and the lens has less work to do.
As a result, the light rays are able to focus on the retina. There is an enormous choice of spectacle frames available, to suit all budgets; younger people may even regard them as a fashion accessory. These do the same job as glasses but they sit right on the surface of the eye. Many different types of contact lenses are available. Lenses may be soft or rigid gas-permeable. They can be daily disposable, extended wear, monthly disposable, or non-disposable.
Your optician can advise which type is most suitable for your eyes and your prescription. Contact lenses tend to be more expensive than glasses. They require more care and meticulous hygiene. They are more suitable for older teenagers and adults, rather than very young children.
0コメント