Short-sightedness (Myopia): Origin and correction

Many people suffer from mild or severe short-sightedness. It is one of the most common diagnoses at an eye specialist and can be well treated with glasses. Learn more here about this widespread form of defective vision.

What is short-sightedness?

Short-sightedness, known medically as myopia, is a condition in which the normal function of the eye is disturbed. With normal vision, the human eye can recognise what it sees sharply, irrespective of light conditions or distance. The light rays are refracted so that the focal point is exactly on the retina. With short-sightedness, the incoming light rays are already bundled in front of the retina, which produces blurred vision. Short-sightedness is one of the most common forms of poor vision, affecting about a quarter of the German population.

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What causes short-sightedness?

The causes are (more rarely) too much refractive power of the cornea and/or lens (refractive myopia), an above-average length of the eyeball (axial myopia), or a combination of both. In all cases, the focal point is in front of the retina.

How do I know whether I am short-sighted?

Affected people can recognise whether they are short-sighted by the fact that they can no longer see distant objects sharply. However, objects close by are detected sharply and clearly without any problems.

The following symptoms can be a sign of short-sightedness:

Seeing sharply at a distance causes problems, for example when reading street names or posters. School children
can only read the writing on the blackboard indistinctly.
The ability to see at dusk or at night decreases.
Those affected only recognise people's faces when they get closer.
Headaches can occur, for example, when driving a car, as seeing puts a lot of strain on the eyes.
Short-sighted people often squint their eyes to see more clearly.

What is short-sightedness and what is long-sightedness?

People who are short-sighted can clearly see objects close up, but have problems seeing things in the distance. It is different for people who suffer from long-sightedness: For them, near objects appear blurred and indistinct, but they can see distant objects better.

Both types of defective eyesight are widespread in the general population. With increasing age, so-called age-related far-sightedness (presbyopia) occurs, in which those affected also have difficulty in seeing close objects, or increasingly notice blurred vision when reading.

What types of short-sightedness are there?

Basically, short-sightedness is divided into two types:

Myopia simplex (physiological myopia): This is the most common type and often occurs at school age, around the age of ten to twelve. This is why it is also called school myopia. The values change until eye growth is complete, i.e. around the age of 25 years. In most cases, only mild to moderate myopia is present (up to -6 dioptres).
Myopia maligna (progressive myopia): This type of short-sightedness is usually congenital and continues to progress through adulthood. The values are above -8 dioptres and can get increasingly worse. Degeneration of the retina, the choroidea and the vitreous body can occur; the risk of retinal detachment is very high in this case.

Since short-sighted parents can pass on the defective vision to their children, even small children should be examined for possible short-sightedness from the first year of life.

Also interesting:Far-sightedness: Origin and correction

How is short-sightedness corrected?

It is not particularly dramatic if the ophthalmologist detects short-sightedness during an eye test. Nowadays, poor eyesight can be corrected and compensated for by a visual aid:

Glasses: The treatment of short-sightedness is usually achieved by wearing glasses. A concave, i.e. inwardly curved, diverging lens is used to correct the refractive error. This changes the refraction of the incoming light rays so that they are first focused on the retina and a sharp image is created.
Contact lenses: Wearing contact lenses is an alternative option. However, they should only be used following the exact instructions of your eye specialist or contact lens specialist and should never be left in your eye for too long, otherwise dry eyes or other eye diseases may develop.

If you suffer from short-sightedness, you can also have the refractive error corrected by a surgical procedure (refractive surgery). The costs for this usually have to be covered by the patient.

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What are the dioptre values for short-sightedness?

The unit of measurement for the refractive power is called dioptre (dpt). If short-sightedness is present, these dioptre values, which are measured by an eye specialist or optician, are in the minus range, i.e. have a negative refractive value. If the specialist finds a value of -0.25 dpt, for example, it is only a case of slight short-sightedness. The higher the value (e.g. -4.0 dpt), the more severe the refractive error.