The word myopia derives from the Greek word "myopia" and means "Blinzelgesicht". In fact, nearsighted people blink more often to better recognize things in the distance. Short-sighted people only see sharpness on short and shortest distances.
The extent of myopia is given in diopters (dpt). The unit of measurement describes how much a spectacle lens must break the light so that the ametropia is corrected. Negative diopter values stand for myopia, positive for long-sightedness. The greater the value, the stronger the correction must be and the worse the affected can see without visual aid.
Between 15 and 49 percent of the German population are short-sighted, including many children and adolescents. Experts expect that in 2050 at least every second inhabitant in Western Europe will have difficulty seeing sharply in the distance.
For the World Health Organization WHO, myopia is already one of the five most important eye diseases that need to be curbed. The reason: It causes serious eye problems such as macular degeneration, retinal detachment and glaucoma.
Ophthalmologists refer to a pathological or high myopia when the eyesight is weakened by at least -6 dioptres. Retina and choroid are particularly tense due to the elongated eyeball. As a result of stretching, the retina may loosen or tear, sag and scar. Microcracks in the retina cause vessels to proliferate and worsen vision. Experts also speak of myopic maculopathy. By 2050, every tenth in this country should have a pathological myopia.
The so-called malignant or malignant myopia is rare. The eyeball grows so extreme that people have a poor vision of up to -30 dioptres. Different structures of the eye are particularly susceptible under such extreme conditions: Above average, the retina dissolves. The yellow spot, also known as the point of sharpest vision, is more commonly damaged. Those affected can even go blind. Malignant myopia is hereditary. Currently, one to three percent of the population suffer from this dangerous form of myopia.
If one eyeball grows normally and the other lengthens, one's sight is short-sighted in only one eye. Differently long eyeballs result in different dioptric values for the two eyes.
A nearsightedness can be better understood if one imagines the eye as a camera. The cornea and lens form the lens, the retina is the film. Lens and cornea break the incoming rays of light, the reduced image arises on the retina.
Short-sighted people usually have an elongated eyeball. This does not create the image directly on the retina, but in front of it. An eyeball elongated by one millimeter already leads to a myopia of -2.7 dioptres. The longer the eye is, the greater are blur and low vision.
A rare reason for myopia is refractive myopia. Here, the lens, aqueous humor and cornea are changed so that the focal point of the light rays is displayed in front of the retina. The eyeball is usually normal.
It is hereditary that the eyeball grows excessively. About ten to fifteen percent of the children are short-sighted when a parent is also short-sighted. The risk increases three-fold, should both parents in the distance see poorly.
Lack of daylight and short sight distances stimulate the eyeball to grow. The visual, learning and leisure behavior that is widespread today plays a major role in the increasing short-sightedness. Instead of spending a lot of time in the fresh air, much of everyday life takes place indoors. The constant view of tablet, smartphone or computer screen prevents the relaxing view.
The new technologies are the main reason why nearly all young people are short-sighted in Asian countries like China. Even reading under the coverlet with flashlight can increase myopia.
Most of the time shortsightedness becomes clear when the children go to school. They no longer recognize the writing on the board or have difficulty deciphering advertising letters, posters or screens in the distance.
Short-sighted people also stand out because they blink a lot or their eyes pinch. At the same time the eyelid gap narrows. In the pupil penetrate less light rays. The beam gets smaller and strikes another point - at best directly on the retina.
Headache in myopia
For the eyes, it means stress, to continuously compensate for the visual defect and to focus the image. Short-sighted people contract numerous muscles of the head and face as well as the neck when they are close-eyed and blinking. This causes headaches.
Shortsighted you will not get up from one day to the next. As the child grows, so does the eye. At the same time, however, the corneal refractive power decreases until the age of twelve, so that the light rays initially remain at the center of the retina. If the eyeball then continues to grow, the myopia develops. Through this phenomenon, myopia increases even in adolescence to early adulthood. Short-sightedness is among the 24-year-olds most prevalent according to studies.
How quickly myopia progresses depends, among other things, on the viewing habits and the genetic conditions. Usually the eyeball stops growing between 25 and 30 years. If you want to have your eyes lasered, you better wait until the dioptric value is constant for two years.
Ophthalmologists or opticians diagnose myopia with the help of an eye test. He checks whether there are pathological changes of the eye hidden behind the harmless defective vision. Depending on the findings, he will initiate further tests, such as measuring intraocular pressure or examining the eye with a slit lamp.
In the eye test, the expert checks the view in the distance. He uses eye charts hung five to six meters away. They map numbers, e-hooks or landolt rings. The patient must recognize the numbers or indicate in which direction the ring or the E is open. One eye is covered. The eye to be tested is tested by the expert with and without corrective glass.
An eye test may vary depending on the light conditions and the time of day. Visual acuity is reduced by about half when it gets dark. In the dark, we only see one-tenth of the day's sight.
Myopia can not be cured. Short-sighted people need glasses, contact lenses or artificial lenses to see clearly. The visual impairment can also be corrected by laser.
Laser: Eye surgery for myopia
For about 30 years, eye surgeons have been reading myopic eyes. They wear off tissue and thus weaken the refractive power of the cornea so that the focal point of the incident light hits directly on the center of the retina. The Refractive Surgery Commission recommends lasers to people who are not short-sighted.
The best known laser method is the LASIK method. Others are LASEK and PRK. The methods differ in terms of their advantages and disadvantages. In LASIK, for example, the surgeon prepares a corneal disc, which he folds away. Then, in the deeper cornea, he planes away as much tissue as the preliminary examinations have determined. Finally he closes the corneal lid again. Patients are not in pain and the sight is recovering quickly. For the corneal lid can slip.
In the modern SMILE procedure, the eye surgeon uses the femtosecond laser to prepare a small, lenticular slice of the corneal tissue. The disc is removed by a minimal cut also made by the laser at the edge of the cornea. The upper layers of the cornea and the corneal nerves remain intact. Side effects such as dry eyes, double vision or bad night vision occur less frequently.
Overall, the success rate of laser surgery is very high. But not all visual defects can be optimally corrected. Occasionally a second operation is required. In the first three months, side effects are relatively common. Thereafter, nerve fibers have regenerated, which were injured during the procedure. Long-term side effects occur especially when the patients had symptoms before surgery. Studies show that the more experienced and experienced a doctor is in the laser methods, the less common are the complications.
The cost per eye 1000 to 2500 euros. Around 25,000 Germans travel abroad each year for a laser surgery to save money. The German Ophthalmological Society (DOG) advises against such cheap offers. Abroad, hygiene and staff are often saved. The education about the surgery and its risks is usually only in English. Follow-up examinations are omitted. If there are any complications you have usually left the country again.
Correct myopia with glasses
Most people wear glasses to correct their vision problems. Opticians adapt myopia to a so-called minus glass. The glasses change the focal length so that a sharp image is created on the retina again. The refractive index of the glass corresponds to the refractive error. It is given as the visual defect in dioptres (dpt).
The advantage of glasses: If the eyesight changes, the optician can replace the old one with a corrected one. Glasses are especially useful if the values are still changing, as with children and adolescents. Thanks to lightweight plastic lenses with high refractive power, glasses of strong short-sighted people are not particularly difficult these days.
Correct myopia with contact lenses
Even contact lenses correct myopia. The lens does not float in front of the eye, but floats on the eyeball. Especially people with high dioptric values often prefer contact lenses, because the strong negative lenses of a pair of glasses restrict the field of vision, degrade the imaging quality and are comparatively difficult.
Contact lenses have many advantages: they are invisible and do not change the look. They allow extreme movements and sports without restrictions. The dioptric values can be easily adjusted, the contact lens removed at any time and even change the eye color with the help of colored models. Many short-sighted people use glasses or contact lenses depending on the situation.
If you want, you can also use permanent contact lenses. The ophthalmologist implanted the so-called phakic intraocular lens (PIOL) between the iris and the body's own lens (phakos: ancient Greek for lens). The PIOL stays in the eye. The ophthalmologist can replace them at any time. The method is suitable for people who are short-sighted and whose cornea is too thin to laser.
An alternative are artificial lenses, which are exchanged against the body's own lens. With art lenses, short-term and presbyopia can be corrected at the same time as with progressive lenses. Art lenses are particularly useful for the elderly, who are very short-sighted, not for a laser surgery in question and do not want to wear glasses.
Myopia often begins in childhood and adolescence. The eye usually grows until the age of twelve. In myopia, growth is not properly regulated by different factors. This includes a genetic predisposition, but also frequent sighting in the vicinity and too little daylight.
Myopia in toddlers
Myopia is inherited, among other things. Short-sighted parents should have their children checked by the eye doctor or pediatrician regularly - at least once a year from preschool age once a year. Especially with smaller children, myopia is often hidden from parents. Much of what interests the offspring takes place nearby. Painting, playing, reading aloud - that's what it's all about if you can see clearly at short distances. Many ophthalmologists go a step further. They recommend that children should be ophthalmologically examined at the age of two and a half to three and a half years.
Myopia slow down in children
Myopia should be corrected immediately. Short-sighted children need glasses when they are cycling, playing outdoors or reading something on the blackboard. Unlike long assumed, myopia does not increase with them because of the glasses, but because the eyeball continues to grow. The visual defect deteriorates according to studies slower, if the optician optimally corrects the visual defect.
It has long been believed that myopia is slowed down by slightly undercorrecting the eye. Because the eye constantly strives to compensate for the residual error, it would be trained, so the assumption. According to recent results, the opposite is the case: Undercorrecting causes myopia to increase more rapidly.
Short-sighted, always short-sighted. Even with advancing age, the myopia persists. In addition, in most people from around the middle of 40, there is a presbyopia, also called presbyopia. The elasticity of the eye lens diminishes.
Short-sighted people often have an advantage when compared to people who are far-sighted or normal-sighted: they do not necessarily need reading glasses or varifocal lenses in old age. For short distances, they simply take off their glasses. Short-sighted people with presbyopia, whose visual defects are not compensated in the vicinity, use multifocal contact lenses or progressive lenses.
The rumor persists: With eye exercises or a special eye training could be a myopia abtrainieren. The exercises should relax, stimulate blood circulation and improve vision. So far, nothing has been proven scientifically.
On the contrary: specialists warn against fraudulent offers. The courses, often offered by naturopaths and self-appointed health trainers, sometimes cost a lot of money and do nothing. The eye muscles move the eyes, but they do not play a role in cases of ametropia. Shrinking does not make a prolonged eyeball even with so massive a workout because it is not a muscle.
Shuning myopia with daylight and visual breaks
Bright light causes the retina to release more dopamine. The messenger prevents the eyeball from growing. Experts recommend that children spend at least two hours outdoors each day. In a Chinese study, 40 minutes of fresh air were enough daily for positive effects.
Seeing at short distances is considered a risk for myopia. Therefore, experts recommend less work on the computer screen or smartphone. To positively influence the course of myopia, children should spend a maximum of 30 hours with near vision. Compared to the lack of daylight, however, sewing is the lesser evil.
How good daylight therapy and visual pauses work, shows an example from Taiwan. There students have to air two hours a day. Thirty minutes of reading is followed by ten minutes in which the eye pauses nearby. Since 2012, the infantile myopia in the Chinese island state is declining.