Myopia – What is short-sightedness?

Author: Dr. Victor Derhartunian 12 April 2024

Myopia is also popularly known as short-sightedness. It is a form of defective vision in which objects in the distance are perceived out of focus. In this article, you can find out more about myopia – how to recognize it, diagnose it and what treatment options are available.

Symptoms of myopia

People with myopia see objects sharply at close range. The blurred vision is only limited to the distance. The first signs of myopia are often poor distance vision at night or regular headaches. Numbers on blackboards, letters on walls or signs and objects in the distance become increasingly difficult to see. Those affected tend to squint their eyelids in order to see more clearly – this reduces the size of the pupil and improves depth of field.

Is nearsightedness and farsightedness possible at the same time?

In the case of long-sightedness (hyperopia), on the other hand, vision at close range is restricted. It is even possible for short-sightedness and long-sightedness to occur at the same time . For example, one eye can be affected by myopia while the other eye is affected by hyperopia. In addition to short-sightedness, age-relatedpresbyopia can also occur in old age. Contrary to what is often assumed, presbyopia does not cancel out short-sightedness, as the visual defects affect different areas and have different underlying causes.

Risk factors for myopia

Some diseases can promote short-sightedness:

  • Diabetes mellitus
  • Cataracts
  • Marfan syndrome
  • Down syndrome

If you are affected by one of these diseases or if myopia runs in your family, you should consult an ophthalmologist if you experience symptoms of short-sightedness. In addition to the diseases mentioned, an accident can also cause lens fibers to be damaged, resulting in myopia.

Causes of myopia: Why does short-sightedness occur?

Normally, the focal point is on the retina – this produces a sharp image. In people with myopia, however, the focal point is in front of the retina. The light rays are focused too early and scatter onto the retina, resulting in blurred vision. There are essentially two different causes of myopia.

Axis myopia

Axial myopia is the most common cause of myopia. In this case, the focal point is in front of the retina. The reason for this is that the eyeball is too long. Axial myopia is inherited recessively, but can also be favored by premature birth. A particularly pronounced axial myopia is also referred to as pathological myopia.

Refractive or refractive myopia

Refractive myopia occurs less frequently. In this case, the refractive power is too high. This can be caused by the lens of the eye if the lens is clouded by a cataract. Furthermore, the refractive power can be increased due to the cornea as a result of corneal curvature (e.g. keratoconus). The eyeball is normal in refractive myopia.

If refractive myopia only occurs for a short period of time, it is referred to as transient myopia . This is a temporary visual impairment that can be caused by overloading the eye or external factors such as medication or drug use.

External influences

In addition to heredity, other everyday influences can promote short-sightedness. These include, in particular, excessive work in the near field of vision :

  • Read books
  • Screen work
  • Use of smartphones

These are all activities in which the eye focuses exclusively on the near range, which can cause the brain to adapt to the near range. This adaptation of the brain can ultimately lead to myopia.

Types of myopia

Myopia can vary in severity. There are two forms of severity:

  • Simple myopia (myopia simplex, school myopia)
  • Degenerative myopia (malignant myopia, myopia maligna)

Simple myopia is still moderately pronounced with up to 6 diopters. It often causes problems from the age of 10, but does not usually progress from the age of 20.

Progressive short-sightedness up to the age of 30 is referred to as benign progressive myopia . This can reach a value of up to 12 diopters. Myopia that increases beyond this is called degenerative myopia.

Degenerative myopia is usually characterized by particularly high diopter values.

Consequences of myopia

Short-sightedness can lead to secondary problems. This particularly affects patients with degenerative myopia. Possible secondary problems are

  • Overstretching of the eyeball wall
  • Increased risk of damage to the choroid or retina
  • Risk of retinal detachment

In particular, the increased risk of retinal detachment should not be underestimated, as this can lead to blindness. It is therefore advisable for those affected to have their retina examined regularly and to consult an ophthalmologist immediately if they experience symptoms (flashes of light, restricted field of vision, soot in the eye) of retinal detachment. A retinal detachment is always an ophthalmologic emergency.

Diagnosis of myopia: how it is recognized

Following a comprehensive medical history, various eye examinations are carried out to diagnose myopia. The most important of these is the refraction test. As part of the refraction determination, a correction value is determined that is necessary to compensate for defective vision. A distinction is made between objective and subjective refraction determination.

In objective refraction determination, the refractive power of the eye is automatically determined using a refractometer. In subjective refraction determination, an eye test is carried out. The patient is fitted with various corrective lenses while having to recognize and describe letters and numbers.

Options for correcting myopia

Myopia is a structural change in the eye. It is therefore not possible to train away short-sightedness. However, there are two ways to correct the visual impairment: Visual aids and laser eye surgery.

Visual aids (glasses or contact lenses) for myopia

Myopia can be compensated for using a spectacle lens with negative refractive power. Concave lenses are used for this purpose, which are curved inwards by the necessary correction value and deflect the light rays in such a way that the focal point is directed back onto the retina of the eye. This results in sharp vision.

Contact lenses can also be used. These are suitable for both weak and strong short-sightedness. However, it should be noted that contact lenses can cause damage to the cornea if worn for too long and can be a source of infection. Careful use is therefore advisable.

Laser eye surgery for short-sightedness

Refractive surgery also offers many options for correcting myopia through surgery. There are various types of treatment to choose from:

You should discuss which procedure is most promising for you with your ophthalmologist. The advantage of a surgical procedure is that you are generally no longer dependent on visual aids and can instead enjoy your life with new and clear vision. In addition, laser eye surgery in particular has a very low complication rate and a high success rate .

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Author:

Dr. Victor Derhartunian

Nachdem er sein Handwerk von den beiden Pionieren der Laserchirurgie gelernt hat, gehört Dr. Victor Derhartunian zu den führenden Augenlaser-Chirurgen. Er leitet die Praxis in Wien und kann seine Patienten in fünf Sprachen beraten.