Why can myopia improve with age
Myopia: causes and therapy
Myopia - in a nutshell
Myopia have problems recognizing distant objects. This is because either your eyeball is relatively too long or the refractive power of your eye is too great. The dioptric value required to correct the poor eyesight can be determined with the so-called refraction measurement. Myopia can be treated with glasses, contact lenses or an operation such as a laser.
With nearsightedness (myopia), it is difficult to see into the distance. Myopia see objects farther away indistinctly and blurredly, while they can easily see objects close by.
Causes of myopia
Myopia can have two different causes:
1) The eyeball is too long (= axial myopia)
2) The refractive power of the lens, aqueous humor and cornea is too great in relation to the normal length of the eyeball (= refractive myopia)
The result is the same in both cases: while with normal sighted people the focal point, i.e. the place at which a sharp image is created from parallel incident rays, is in the retina, with nearsighted people it is in front of it. There is a fuzzy image in the retinal plane, which is then also perceived in the brain.
Axial myopia is more common. Premature babies are at increased risk for this form of myopia.
Myopia - briefly explained in the video:
What is a diopter?
The refractive power of the eye is measured in the unit of dioptre (dpt). The normal value for a healthy eye at a great distance is around 60 to 65 dpt. In the case of ametropia, the number deviates from this value. How strong the deviation is in the individual case is indicated with a plus for farsightedness and a minus for nearsightedness (for example -1.5 dpt).
Forms of myopia:
- Simple myopia (myopia simplex) or benign myopia:
This hereditary form of myopia usually begins between the ages of ten and twelve. Even if school attendance and the activities carried out during this time have been shown to have no influence on myopia, this form is also known as "school myopia". For most of those affected, myopia no longer increases after the age of 25. However, sometimes it can progress to the age of 30. Many sufferers then achieve a value of -6 to -8 diopters.
- Malignant myopia (myopia magna or myopia progressiva):
With this form of myopia, the eyeball is stretched regardless of external influences. This can affect the retina and choroid: they become thinner and the tissue begins to shrink. Typical of the disease is the so-called "fox spot", which is caused by bleeding and the subsequent development of a pigmented scar in the area of the yellow spot (macula). Malignant myopia not only increases poor eyesight, there is also an increased risk of the retina becoming detached (ablatio retinae).
Symptoms: how does myopia show up?
In the case of nearsightedness, those affected have difficulty seeing objects in the distance, whereas they can see perfectly close up. Accordingly, activities such as reading and working on the screen are usually not impaired.
The following complaints can indicate myopia:
- The further away an object is, the more blurred it appears
- Faces and people are recognized late
- Problems reading street names and house numbers
- Reading projected texts (for example at school, university or at work) is difficult
- No individual leaves or branches can be seen on trees
- Illuminated signs or other light sources are perceived as blurred
- Headache, especially during and after activities that require clear vision, such as driving a car
The standard examination for suspected nearsightedness is an eye examination by an ophthalmologist or optometrist.
Caution: The results can vary depending on the time of day, lighting and general well-being. To adjust glasses, it can therefore be helpful to check the values several times.
In an eye test, the ophthalmologist or optician checks how well a person can see into the distance (television focus or distance vision) and up close (near vision acuity or near vision). The test for myopia is carried out using eye charts at a distance of five to six meters. First, with the left eye covered, the right eye is examined once without and once with corrective glass. The other eye is then tested according to the same scheme.
If it turns out that myopia is actually present, it is advisable to consult an ophthalmologist to be on the safe side. He can determine if there are other diseases or changes in the eye that may need treatment.
Because myopia increases the risk of retinal detachment, it makes sense for those affected to have their eyes checked by an ophthalmologist at regular intervals (for example every two years). If you are nearsighted, talk to your doctor about whether and at what intervals he recommends such checks.
When determining the refraction, the refractive index of the eye is measured. When determining the refraction, there are two methods to choose from, which are used one after the other to determine the necessary values for the glasses or contact lenses:
- In the case of objective refraction, the image is automatically adjusted with lenses that can be connected in series so that it appears sharp to the nearsighted person. The values at which the sharp image appears are the starting value for the subsequent subjective refraction determination.
- In the subjective refraction determination, the result of the objective refraction measurement is checked for each individual case. The decisive factor now is the individual visual impression and thus the correction value that enables optimal visual comfort. The nearsighted person decides for himself with which lens he sees best. This value is then used for the correction.
Myopia can be corrected or compensated for by wearing glasses or contact lenses. Glasses for nearsighted people contain diverging lenses with a negative refractive index. They move the point at which distant objects are sharply imaged so that it lies directly in the retinal plane.
Eye surgery is another way to correct myopia. In particular, people who do not want to or cannot wear glasses and contact lenses are interested in this therapy option. Although they are not a standard treatment, lasers are increasingly being used to correct myopia. As with all surgical procedures, there are surgical risks involved with these procedures. The procedure can lead to infections, over- or undercorrection of the poor eyesight (i.e. a formerly myopic person becomes farsighted after the procedure or a remainder of the myopia remains) as well as increased sensitivity to glare.
The laser surgery mostly performed today to correct myopia is the so-called LASIK (Laser-Assisted In Situ Keratomileusis). Important prerequisites for this are a sufficient corneal thickness and the fact that the eyesight has not changed significantly in the past few months. The ophthalmologist must perform a thorough eye examination before the procedure and then carefully advise and educate the patient.
This is how a LASIK operation works
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