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Long Sight - Hypermetropia

long sight


What is a refractive error?

A refractive error is an eyesight problem. A refractive error means that the eye cannot focus light on to the retina properly. This usually occurs either due to abnormalities in the shape of the eyeball, or because age has affected the workings of the focusing parts of the eye.

There are four types of refractive error:

  1. Myopia (short sight).
  2. Hypermetropia (long sight).
  3. Astigmatism (a refractive error due to an unevenly curved cornea).
  4. Presbyopia (an age-related refractive error).

When we look at an object, light rays from the object pass through the eye to reach the retina. This causes nerve messages to be sent from the cells of the retina down the optic nerve to the vision centres in the brain. The brain processes the information it receives, so that in turn, we can see.

The light rays have to be focused on a small area of the retina; otherwise what we look at is blurred. The cornea and lens have the job of focusing light. The shape of the lens is varied by the small muscles in the ciliary body. 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.

What is long sight (hypermetropia)?

Hypermetropia occurs when light is focused behind the retina. People with long sight cannot accommodate fully and so the light does not focus sharply and vision is blurred. This occurs because the eyeball is too short, the cornea is too flat, or the lens cannot become round enough.

People with a minor degree of long sight, can usually see at distance, and their near sight is clear. However, a person with long sight may get tiring of the eyes, often with a headache and vision discomfort. People with more severe hypermetropia are not able to see near objects clearly in focus.

What causes long-sightedness?

The causes of hypermetropia are usually genetic (hereditary). Long-sightedness can occur at any age but it tends to become more noticeable above the age of 40 years. In rare cases, hypermetropia 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.

A particular type of age-related long-sightedness called presbyopia occurs because the lens of the eye becomes more stiff with age.

What are the symptoms?

The main symptom is a difficulty with near vision. 'Tiring' of the eyes (asthenopia) is common and long-sighted people may have headaches and uncomfortable vision. Long-sighted people may have difficulty with depth perception (3-dimensional vision).

Are there any complications?

In severe cases of hypermetropia present from a very young age, amblyopia (lazy eye) can develop. The affected eye(s) does not learn how to see because the brain ignores the signals it receives.

What is the treatment for long-sightedness?

  1. Glasses
  2. Contact lenses
  3. Surgery

Laser eye surgery is expensive but offers the chance to restore normal sight permanently. The 'cure' is usually instant and the procedure is generally painless. Several types of laser surgery have been developed. These include: LASIK, PRK and LASEK. They are similar because the basic idea is to reshape the cornea using the laser to remove a very thin layer. The reshaped cornea allows the refraction of the eye to be corrected.

LASIK®

LASIK stands for L aser-As sisted I n situ K eratomileusis. This is the most popular form of laser eye surgery. The laser is used to lift and remove a very thin layer of the cornea. The shape of the cornea is altered to be more curved, so that the light rays can be focused further forward, and on to the retina.

How often do I need an eyesight test?

This depends on your age, your family history and any pre-existing medical conditions.

As a guide, if you fall into the high-risk group, you should have at least an annual (yearly) eye examination if you are over 60 years of age. If you are over 50 years of age it should be every two years, and over 40 years, with risk factors, then an eyesight check is recommended at least every three years.

Low-risk people with no symptoms of an eyesight problem, do not need to have their eyes tested so frequently. If you fall in this group and are aged between 19 and 40 years, an eye test is needed every 10 years. Between the ages of 41 and 55 years, it is recommended that you see an optometrist five-yearly. At any age between 56 and 65 years, two-yearly checks are needed, dropping to annual checks in low-risk people who are 65 years old or more


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