Myopia is becoming a serious problem in many countries. In urban areas of Asia, almost 90% of people younger than 20 years have myopia — a tendency, which continues throughout the world. Researches predict, that by the year 2050 nearly 60% of the world's population may be myopic. In the worst case, early myopia can lead to a severe form of myopia with changes in the fundus, which can lead to a steady loss of vision.
Myopia has a multifactorial etiology, where genetics play a key role, as well as environmental factors and the nature of visual load. In the modern world, where the amount of physical activity and the time spent in open space have decreased, but the visual load has increased, the number of people with myopia grows in arithmetic progression.
Why monitor the progression of myopia?
Higher levels of myopia are associated with an increased risk of retinal disease and a higher risk of glaucoma, which threaten the vision in later life.
The goal of myopia control is to slow down the progression of the desease, to help maintain eye and vision health. "Myopia control" is becoming an increasingly used term to describe treatment methods, aimed at slowing down the progression of myopia. These treatments include special types of optic lenses (eyeglasses), soft contact lenses, ortho-k and eye drops with atropine.
How does myopia control work?
The most common cause of children's myopia and its progression is an axial elongation of the eye, when the eyeball becomes too long from front to back. In general, myopia control works by slowing this elongation.
Methods of myopia control
Currently, there are several methods for controlling myopia, which can be used individually or in combination, to counteract the development or progression of myopia:
- Contact lenses for myopia control — soft with peripheral defocus or orthokeratological.
- Eyeglasses for myopia control.
- Eye drops — low doses of atropine.
- Adjusting the daily habits — increasing time outside in the fresh air and reducing long-term work activities at close range. Sunlight is an important regulator of eye growth, so outdoor time is very important.
Contact lenses for myopia control
Myopia control contact lenses are different from myopia correction contact lenses.
Contact lenses for myopia control have different focusing power in different zones. They have the full focusing power in the center, but less focusing power on the periphery. These areas of lower focusing power ensure that all the light, that gets into the eye, focuses in front of the retina.
This is called peripheral myopic defocus.
Researches show, that focusing light in front of the retina in this way can stop the eye from elongating. In fact, contact lenses for myopia control can slow down the progression of myopia by up to 59%.
Multifocal contact lenses, that are used to correct presbyopia, may also help to slow the progression of myopia. However, their effectiveness in slowing myopia reaches only 49%.
Orthokeratology
Orthokeratology, also known as ortho-k, is a common type of vision correction.
Ortho-k uses special rigid gas-permeable contact lenses, which are worn only at night. The lenses temporarily change the shape of the cornea during sleep, therefore, the next day the vision becomes clear.
This temporal change also creates peripheral myopic defocus and reduces peripheral hyperopic blur. Studies have shown, that ortho-k therapy can reduce eye elongation.
Atropine eye drops
Atropine works due to its effect on special receptors of the sclera of the human eye, which contributes to the arrangement of collagen fibers in the membrane of the eye.
Researches show, that low-dose atropine eye drops (0,05%) may slow down the progression for more than three years. This can have a big impact, if children use the drops during the peak years of myopia progression.
But some children may experience a rebound effect even with low doses of atropine. This means, that the progression of myopia may accelerate again after stopping the use of eye drops. However, the number of myopic rebounds and the number of children, who experience them, is very small.
Eyeglasses for myopia control
During the last 8-10 years much research has been done and significant progress has been made in the development of glasses for myopia control. Researches show, that this new correction device can reduce the progression of myopia by more than 60%.
Myopia control eyeglasses work the same way, as myopia control contact lenses. They can slow down the elongation of the eye, by creating a peripheral myopic defocus.
The newest glasses for myopia control can both correct, and control myopia, and are also a more effective option than contact lenses. This is a very attractive prospect for the practice of myopia control, because eyeglasses are easier to put on (not all children are ready to learn to wear contact lenses).
How do they work?
When it comes to theories of myopia control mechanisms, the most modern isthe theory of peripheral defocusing, according to which the peripheral retina receives myopic defocus as a signal to slow down or stop the eye growth.
For comparison, monofocal eyeglasses or monofocal contact lenses form hyperopic defocus — the image is focused "behind the retina", which can lead to the progression of myopia.
In recent years, the theory of peripheral myopic defocusing of the retina has become popular. Think of it as two planes of focus: one is on the retina to correct myopia, and the other is in front of the retina for myopic defocusing, which can be anywhere on the retina, and not only on the "periphery".
Lens designs for myopia control use different patterns in the peripheral parts of the lens, which focus the light in front of the retina, to act as a stop signal for eye growth, which leads to a reduction in the progression of myopia.
Eyeglasses with a special innovative SmartVision lens
SmartVision Lens uses a unique design with concentric rings, which gradually reduce the optical power from one ring to another, creating a smooth focus transition.
The total defocusing range of these lenses is from 3.0 to 4.0 diopter, making them an ideal choice for most children with myopia.
Clinically proven to be effective in slowing the progression of myopia up to 60%.