Myopia in teenagers is a common problem. According to a systematic review study, the myopia rate among Chinese teenagers aged 16-18 is about 84.8%.
It is also conceivable that parents are concerned about their children’s myopia. You may have heard a lot of various myopia science extensions from this, such as the saying that “eating sugar can cause myopia”, and even some ophthalmologists think so. , but is this true?
01 What is said on the Internet about sugar and eyesight
When searching for “sugar, myopia” on the Internet, the results basically confirm the statement “sugar can cause myopia”. According to the relevant description, the reasons can be summarized into two points:
- Consuming too much sugar will cause calcium to be lost from the body, affect the toughness of the eyeball wall, make the eye axis easily elongate, and promote the occurrence of myopia.
- Eating too much sugar leads to an increase in blood sugar and a decrease in the osmotic pressure of body fluids. The aqueous humor in the eyeball penetrates into the lens, causing the lens to deform and increase the diopter, thereby causing or aggravating myopia.
Let’s look at the first statement first: “Consuming too much sugar will cause calcium to be lost from the body.” If calcium loss really occurs, the growth and development of the bones will probably bear the brunt rather than the so-called toughness of the eyeball wall.
In addition, although the lengthening of the eye axis is indeed the cause of myopia, we have also popularized science before. There is currently no very definite conclusion on the cause of myopia. It is relatively clear that genetic genes play a relatively large role.
Therefore, no matter how complete the relationship between sugar and myopia is explained on the Internet, it is only theoretical speculation without evidence support and cannot be fully believed.
So what’s going on with the second statement?
02 The only disease that can link sugar to vision
When I was studying the epidemiology of myopia at the New England College of Optometry, I discovered that the only problem related to sugar that affects vision is diabetes.
Diabetes can cause temporary myopia or hyperopia, which is caused by the refractive change of the eye lens due to out-of-control blood sugar. However, after the blood sugar returns to normal levels and stabilizes, the eyes will return to normal.
Diabetes has a greater impact on the eyes and may cause diabetic retinopathy, such as retinal hemorrhage, macular edema, neovascularization, retinal detachment and even blindness.
Therefore, diabetic patients need to undergo regular fundus examinations. But it can be seen that these diabetic retinopathy have nothing to do with myopia.
For healthy people, after eating sugar, the body will automatically adjust. In normal people, the blood sugar concentration can be maintained within a certain range, so it will not cause blood sugar to become out of control and affect vision. This is especially true for healthy children. in this way.
03 Limited research on sugar and vision
Although the saying “eating sugar can cause myopia” is particularly popular in China, there is very little evidence to actually study this relationship.
In 1956, Gardiner proposed that carbohydrates and fats in the diet could cause myopia, but this idea was later abandoned. Many theories are abandoned either because they have been proven wrong by subsequent research or because there is a lack of relevant research.
In 2010, a study found that eating sugar did not increase the risk of myopia in teenagers. Instead, it found that too much saturated fatty acids in the diet were related to myopia.
Recently, there was a French study that used a questionnaire to survey 180 children aged 4-18. The method of this study was to compare the children’s intake of refined carbohydrates (including sugar) with their dilated eye refraction results.
The study found a positive correlation between frequency of refined carbohydrate intake and myopia in girls, but a negative correlation in boys.
In layman’s terms, the study found a correlation such that “girls who eat more sugar have more myopia, but among boys, those who eat more sugar have less myopia.”
There are very few studies on sugar and myopia, but this 2020 study seems to be the only one that has found that eating refined carbohydrates may be related to myopia.
However, this study itself also has many problems, such as failure to control variables (such as outdoor activities, close reading, electronic screen use time, etc.), the questionnaire form itself also has many deviations, and the sample size is not large…
But aside from these, this study only proposed a correlation between myopia and eating sugar, not a causal relationship. Therefore, it is impossible to draw the conclusion that “myopia cannot eat sugar” based on this result.
04 Don’t be influenced by claims that lack evidence and form misconceptions
To sum up, there is still no concrete evidence that eating sugar will increase or reduce the risk of myopia.
Regular consumption of sugar (including refined carbohydrates) is certainly not friendly to the body and teeth. However, if you promote advice that lacks evidence such as “Don’t eat sugar if you are afraid that your children will be short-sighted”, it may cause parents and children to have unnecessary fear of sugar, and it will also cause It may form an illusion: if you don’t eat sugar, you can prevent and control myopia.
On the contrary, this will make parents ignore behavioral interventions that are truly effective in preventing and controlling myopia, such as increasing outdoor activities and reducing the use of eyes at close range. Some people may even have a false sense of security: although their children’s outdoor activity time and use of eyesight cannot be guaranteed. I can’t control my eyes well, but I can’t eat sweets, which is pretty good.
Of course, regardless of whether sugar is related to myopia or not, from the perspective of obesity and tooth protection, eating sugar is indeed discouraged.
05 What can you eat to prevent myopia?
Chinese people pay special attention to the issue of food. On the one hand, they are often worried that eating the wrong thing will make them sick easily. On the other hand, they always hope to solve some health problems through eating.
The same is true for the issue of vision. Some people worry that eating sugar will cause myopia, while others want to know what to eat to prevent myopia, such as lutein, blueberries or carrots. Some people often claim that it is good for protecting eyesight.
But in fact, these claims currently lack evidence, and there is no evidence that what kind of food to eat can effectively prevent myopia or be good for vision.
If you must ask: What kind of food is best for eyesight? My answer is: just eat a balanced diet.
Insisting on ensuring 2 hours of outdoor activities every day and reducing the use of eyes at close range are truly scientific methods that can prevent myopia.
