Scientific research and introduction:
In recent years, scientific research and news reports have mentioned the relationship between ultraviolet rays and myopia, or concluded that ultraviolet rays can prevent and control myopia, or proved that ultraviolet rays are actually not related to the occurrence and prevention of myopia. Past studies have confirmed that excessive UV exposure is directly linked to eye diseases such as cataracts and increases the risk of skin cancer.
Can ultraviolet rays prevent and control myopia?
At present, myopia has become a worldwide problem, and China is the "hardest hit area" for the onset of myopia. According to the results of the 2014 National Student Physical Fitness and Health Survey conducted by the Ministry of Education, the detection rate of poor vision among primary school students in China is 45.71%, 74.36% for junior high school students, and 83.28% for high school students, and the incidence of myopia among adolescents in China is still on the rise.
Relationship between ultraviolet rays and myopia:
In recent years, scientific research and news reports have mentioned the relationship between ultraviolet rays and myopia, or concluded that ultraviolet rays can prevent and control myopia, or proved that ultraviolet rays are actually not related to the occurrence and prevention of myopia.
However, the public who are eager to solve the problem of myopia may not care whether the evidence is conclusive in identifying the scientific nature of news and research, but prefer to avoid all possible hidden dangers and adopt measures that may prevent and control myopia. A common example is that almost all myopia glasses have added a "UV protection" function, although the relationship between ultraviolet rays and myopia is still scientifically inconclusive (of course, it also has the effect of preventing other diseases caused by ultraviolet rays).
What studies found:
Past studies have confirmed that excessive UV exposure is directly linked to eye diseases such as cataracts and increases the risk of skin cancer. Whether ultraviolet rays can prevent and control myopia is widely debated. Therefore, whether to use ultraviolet rays as a means to prevent and control myopia, the public should know more about professional judgment when choosing, rather than "listening to the wind is rain".
There are significant differences in the physiology of the eyes of chicks and humans. For example, UVA (as low as 350nm) can reach the retina well through the cornea, lens and other refractive interstitium of chickens, and the retina of chickens also contains UVA-sensitive cells, so chickens can "see" UVA. Therefore, it is not surprising that UVA upregulates EGR1 and inhibits the development of experimental myopia.
Figures:
However, spectra below 400 nm are barely visible to humans. This is partly because the human cornea and lens block most of the spectrum in this range (10nm-400nm); On the other hand, because the photoreceptor cells of the human retina are not sensitive to spectra below 400 nm, humans cannot "see" UVA.
Similar to chickens, mice can also "see" UVA. Therefore, the study directly used UVA to irradiate mouse retinal cells in vitro, and the experimental results similar to chicks were expected.
Clinical research:
The most critical part of this study is the results of clinical research. This section uses a retrospective study (editor's note: refers to a review of past research results from the "present", which can be colloquially understood as a kind of "follow-up" of past research results) design, comparing the progress of wearing lenses with UV-blocking functions, including contact lenses, on myopia.
Because it is a retrospective study, there are certain differences in factors such as age, sex, initial diopter, and contact lens material (affecting spectral penetration), optical design (affecting optical signals in the retina, etc.) in the process of comparing the two groups, and previous studies have confirmed that these factors also affect the rate of myopia progression.
Therefore, as the author points out at the end of the article, this is a major flaw in this study, and it has not been proved that blocking ultraviolet rays accelerates the progression of myopia (or that it slows the progression of myopia after ultraviolet rays), which has yet to be confirmed by well-designed prospective randomized controlled studies.
The science is inconclusive
It is worth emphasizing that the impact of different wavelengths of visible light on myopia is indeed a topic of concern in the scientific community in recent years. For example, early researchers found in chicks that short-wavelength spectra (such as blue light) can inhibit the occurrence of experimental myopia, and long-wavelength spectra (such as red light, wavelengths greater than 650 nm) can promote the occurrence of myopia (Seidemann and Schaeffel 2002, Foulds et al. 2013), but two independent laboratories have recently found the opposite result in tree shrews (a mammal) and rhesus monkeys: that is, red light can inhibit the occurrence of experimental myopia.
The scientific community still does not have a good explanation for these diametrically opposed findings. Is it simply because the species are different? If so, since tree shrews, rhesus macaques, etc. are closer to humans in species, does this mean that red light is conducive to the prevention and control of myopia? These issues require further study.
But as mentioned above, because the human retina is almost invisible to spectra below 400nm, the relationship between UVA and human myopia has not attracted much attention from the scientific community so far. Even though UVA can cause some aspects of the human retina to respond and play a positive role in the prevention and control of myopia, its potential toxic side effects cannot be ignored. Because the scientific community has long confirmed that long-term exposure to UVA environment promotes the formation of cataracts and significantly increases the risk of skin cancer by inducing genetic mutations in skin cells.
China's "national disease'':
At present, the incidence of myopia remains high, as if it has become China's "national disease", the majority of parents are highly concerned about the eye health of children and adolescents, any report on myopia correction or myopia prevention and control will arouse their great interest. However, any new prevention and control method should be applied after rigorous and scientific experiments. Not only that, but the public should also evaluate its effectiveness while taking a proper view of its potential risks and weighing them!
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