Optical strategy of myopia control implies the use interventions that not only help correct myopia, but also inhibit its progression.
There are three optical methods:
- spectacles that feature lenses of a special design
- orthokeratology lenses
- soft multifocal contact lenses
Spectacles have the least clinical efficacy; however, their significant advantages are ease of use, accessibility and safety. A wide selection of special designs includes perifocal, bi-focal, prism sphere and progressive designs of spectacle lenses. Each of those has its own therapeutic mechanism for managing progression of myopia.
In terms of efficacy, contact lenses vision correction methods which imply orthokeratology and multifocal soft lenses, are significantly ahead of correction by spectacles.
In recent years, a sufficient amount of scientific data has been accumulated indicating a minimal risk of complications of contact lenses vision correction in children and adolescents under conditions of a strict adherence to the guidelines of an ophthalmologist.
The therapeutic principle of orthokeratology lenses and multifocal soft contact lenses is identical: both induce a peripheral myopic defocus which triggers certain complex biochemical mechanisms. As a result, the production of dopamine increases, the level of which directly affects axial length. It is an excessive increase in the length of the eye that leads to myopia progression.
The hypothesis that implies the above stated is called “relative peripheral defocus theory”. Currently, this hypothesis serves as basis for scientific research and development of the most effective methods to slow the myopia progression.
What differences are there between these two interventions?
Orthokeratology lenses are rigid gas permeable contact lens. They are designed for an overnight wear, so the patient must sleep with these lenses on. During the night, ortho-k lenses reshape cornea by hydraulic forces of the tear. Corneal reshaping allows the patient to have a high visual acuity and do without any correction throughout the day. In addition, a therapeutic effect is present. Parents love this method because changes are reversible, because they can be in control of the process of handling and care for the lenses and not worry when the child is without their supervision all day. Disadvantages of this method are increased adaptation time and cost.
Soft multifocal contact lens are designed for daytime use. As soon as the lens is removed from the eye, its corrective and therapeutic effect disappears. Major advantages of this method of correction and control of myopia are versatility and simplicity of use, quick and comfortable adaptation. Handling and care are quite easy even for primary school children. Disadvantages include daily wearing and limited time of use during the day.
Important! Each of the methods described above has own indications and contraindications. Only an ophthalmologist can determine which of the methods suits your child best.
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