In Russia, according to various city health departments and expert estimates, at least 40% of high school students in urban schools have some degree of myopia. Myopia actively progresses between the ages of 6 and 17. It is during this period that it is very important to be able to intervene in the irreversible process as early as possible and slow it down as much as possible because children and adolescents still have a whole life ahead! The quality of life of a person with high myopia degree is reduced – he constantly lacks visual information, and without means of vision correction is almost helpless.
Ortho-K therapy eliminates all the restrictions during wakefulness associated with wearing glasses and ordinary contact lenses — you can run, jump, swim, rub your eyes, etc. This is also very important specifically for children, because they usually lead an active lifestyle and, due to their age, may not fully understand what threatens violation of the rules for wearing contact lenses (for example, getting into eyes with dirty hands).
Finally, children usually spend the night at home and are under the control of their parents, which ensures timely and correct putting on and removing Ortho-K lenses, as well as timely contact with a specialist for follow-up care.
How night lenses work
The human cornea is covered on the outside with several layers of integument cells. When a myope wear an Ortho-K lens (shown in orange), it creates hydraulic forces that cause the epithelium to change shape (shown by yellow arrows). As a result, in the center of the cornea, the number of layers of the epithelium decreases by 1—2, and on the periphery, it increases by 1—2. The central part of the cornea becomes flatter, its optical power decreases, the image focuses on the retina, and the person sees well. This new form of the cornea and good vision persist for some time (until a deep evening or longer), then the effect begins to decrease slowly. If you do not wear a lens, the corneal epithelium gradually restores its former structure, and initial myopia returns.
Hyperopia and astigmatism are corrected by a similar mechanism. For this, other designs of Ortho-K lenses are used that make the cornea in the center more “steep” (convex) or reduce its toricity (toricity is the geometry of the cornea with astigmatism).