Defective vision is not uncommon. Nearly 64 percent of Germans over the age of 16 need visual aids. From the age of 60, it is a full 94 percent. Even children between the ages of 2 and 15 are often lacking a clear view: Already 16 percent wear glasses mostly because of myopia. Why myopia, the technical term for myopia, continues to increase, is not very clear. As a rule, she starts with the prepubertal growth spurt. But scientists suspect that not only genes are responsible for the eyeglass and contact lens boom.
Causes of myopia
The visual impairment can also arise due to influenceable environmental factors, such as close work on the PC or a lot of reading. Biophysicists at Tübingen University and Calgary College have demonstrated in a sensational chicken experiment that prolonged near-vision boosts the eye's growth: the retina sends out growth signals, causing the eyeball to stretch. The result is myopia.
Frameless in the day
When visual acuity subsides more and more, it means loss of quality of life. No wonder then that the offers for better vision increase and glasses and contact lenses fill the shelves of the opticians in a wide variety of variations. About five percent of adults in Germany do not want to see their eyes framed by eyeglass lenses and opt for the "adhesive shells", which obscure a defective vision inconspicuously. Orthokeratology, abbreviated Ortho-K, attracts attention with a special technique which is little known in Germany. A special contact lens made of highly oxygen-permeable plastic reduces myopia during the night or compensates for it completely.
"In orthokeratology, a hard contact lens is adjusted to slightly flatten the cornea, thereby reducing myopia, " explains Dr. Gerald Böhme, Head of the Department of Contact Lenses in the Professional Association of Ophthalmologists in Germany. The lens is not evenly curved like conventional contact lenses, but flattened in the middle, so that it presses lightly on the cornea during sleep and reduces the refractive error from night to night. The method works up to a myopia of -3.5 to -4.5 dioptres. However, the "deformation" of the cornea subsides during the day and thus also the sharp vision; The contact lenses must be used again overnight. How long the Ortho-K effect lasts varies from person to person. For some, it only lasts for one day, others for several.
Orthokeratology originated in the United States, where it was developed more than 40 years ago. The method could not prevail in Germany and was repeatedly criticized by ophthalmologists: The first experience with Ortho-K was negative because of numerous cases of eye damage. Today, the method has improved significantly. Nevertheless, the lens is an additional burden on the eye: "The top layer of the cornea needs to be supplied with oxygen." If you wear lenses every night, less oxygen gets to the eye, causing the cornea to swell up and become cloudy, "warns Böhme, "A healthy eye usually recovers from it, but in older people it can be irreversible."
Complications of orthokeratology
Whether the contact lens can be adjusted depends on many criteria: For people with dry eyes, with a chronic Lidrandentzündung, for allergy sufferers, farsighted or in a medium or high astigmatism, this method is not suitable. "Even in children, I would not recommend orthokeratology, " says the expert. "Because children often rub their eyes at night or lie so that the pillow presses into the eye, then the lens shifts and exerts pressure on the cornea in the wrong place."
The long-term effects of treatment have not been explored. So far, there are only case observations, but do not allow a scientifically sound conclusion. Nevertheless: Orthokeratology works in principle no different than a laser. While the cornea ablates to flatten it, Ortho-K lenses obliterate it. "Unlike the laser, however, the effect is reversible, " says Böhme. "It therefore definitely worthwhile to further develop this method in the future."
Cost of Ortho-K lenses
How much Ortho K lenses cost depends on how fast the treatment strikes. Interested parties must expect 800 to 1, 000 euros, because the development must be checked regularly by the ophthalmologist. In addition, a replacement pair is necessary because a pair of glasses can not compensate for ametropia in the loss of a contact lens when the vision changes during the day. The costs are not covered by the health insurance companies.