Myopia is the most frequent visual defect in the world. In order that countries are industrialized and levels of education grow, the incidence of myopia is also higher. The question is: Which is the reason that we worry about this problem? Myopia is not as the other defects of vision that cause a fuzzy vision and can get improved just using the correct graduated lenses? The answer is no. When it reaches high levels, it becomes a pathological problem. Consequences may include retinal detachment and detachment of vitreous, to be considered as a problem of public health in some countries.
Generally, myopia grows when there is an increase in the size of the eye. And why an eye of normal size continues to grow? This growth is under control by the way that images are focused inside retina. When looking with our glasses or conventional lenses, we see an object focused when its image is formed at the central retina. On the other hand, in the area that surrounds the central retina, the image is formed at the back of the retina being out of focus. This blur of the image represents a stimulus so as to trigger the growth of the eyes and consequently the increase of myopia. This phenomenon is understood as retina was looking for an alignment with the position of the image.
Within our twenty years of experience, we have seen how myopia in many children and teenagers increased with no control and that the methods that were supposed to help us to control it (bifocals, under correction of myopia, agents that reduce intraocular pressure, permeable contact lenses gas) were not as efficient as we expected.
Instead, we are obtaining significant results with operating systems for handling the blur in the peripheral retina such as orthokeratology (Orto-K) and bifocal soft contact lenses.
Orthokeratology (Ortho-K) is a treatment to correct myopia based on the programmed adaptation of special design lenses that perform a molding of the cornea while sleeping, so that the user can see clearly during the day without the need of glasses or contact lenses.
Several studies in the United States (Walline et al., 2009), Hong Kong (Cho et al., 2005) and Australia (Swarbrick et al., 2010), show a reduction of the 50% in the progression of myopia in children treated with orthokeratology compared to those that used glasses or conventional lenses. Corneal changes induced by orthokeratology do that during the day, when the patient uses lenses, the central focus is adequate and can do without glasses or contact lenses while the peripheral approach occurs before the retina. This effect neutralizes believed stimulus that causes the tendency of the eye to grow and thereby become more myopic.
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