With the continuous popularization of medical knowledge and the increasing proportion of myopic teenagers year by year, the term "farsightedness reserve" is familiar to more and more parents, especially many parents have heard that the farsightedness reserve is enough, and the child will not be myopia, so they want to regularly check the farsightedness reserve for their children.
Is it necessary to do this? Or if the child has enough farsightedness, will he really not be short-sighted?
First of all, we have to figure out what exactly is a "farsightedness reserve".
At birth, the eyeball is not fully developed, and the eye axis (i.e., the length of the front and back of the eyeball) is short, which usually manifests as "physiological hyperopia".
Then, slowly, as the child develops, the eye axis naturally elongates and develops into an emmetropic eye around the age of 10, a process called "emmetropia".
Generally, the farsightedness reserve of newborns is about 300 degrees, so physiological hyperopia is the "farsightedness reserve" of newborns.
This physiological hyperopia stage of the eye axis from shortening to normal development is the child's hyperopia reserve, which is equivalent to the savings value of our eyes, which is generally 300 degrees, which will gradually decrease with the development of the child's eyes.
In this process of development, if you "break even", you are "empathic", neither farsightedness nor myopia, and if you are "overdrawn", the eye axis is too long, and it will become myopia.
Genetics, lack of outdoor activities, and poor eye habits will also accelerate the depletion of farsightedness reserves, greatly increasing the risk of myopia.
Secondly, what does it mean that there are more or less farsighted reserves?
As mentioned earlier, the reason why children have farsightedness reserve is because the eye axis is short when they are born, but the eyes will gradually develop, that is to say, the farsightedness reserve is gradually depleted as the child grows older, until one day it will gradually disappear.
In general, the normal refractive state of children of different ages is as follows:
0～3岁：+2.00D～+2.50D
4～6岁：+1.50D～+2.00D
7~9岁:+1.00D
10~12 years old: 0D
This refractive state value is the child's physiological hyperopia value, which is basically the same as the consumption of the child's distant reserves.
In the process of depletion of farsightedness reserves, some children will consume faster, some will consume more normally, and some children may consume more slowly.
Children who consume faster will have more "expenditure" than "income", which will lead to myopia, and the consumption is more normal, and the balance of income and expenditure is normal development, and the consumption is relatively slow, that is, the "expenditure" is less than the "income". This situation is what many parents are more willing to see, because they will feel that they have more farsightedness reserves, and their children will not be short-sighted.
In fact, it is not, too much farsightedness reserve, which means that the child's eyes are underdeveloped and there is a possibility of amblyopia. It's like when we eat, eating too much will hold up, eating too little will cause malnutrition, eating just right can ensure normal body needs.
Third, do I need to measure my farsightedness reserve frequently?
We have always advocated regular vision checks, but it is not necessary to check the farsightedness reserve regularly.
On the one hand, an accurate hyperopia reserve requires adequate mydriatic refraction to obtain results, that is, the results obtained from the vision screening sheet done without sufficient mydriasis are usually inaccurate. In particular, preschool-aged children need to use 1% atropine eye ointment or eye gel for 3-7 days to achieve the effect (traditional slow dilation), which is very energy-intensive.
So while mydriasis is safe, there is no need to do every multi-vision test.
On the other hand, there is a certain pattern in the depletion of farsightedness reserves.
According to a 2022 expert consensus article in mainland China that collected ophthalmological data of children aged 6-15 who are not myopic at the age of 6, it can be seen that children with 50-350 degree hyperopia reserve at the age of 6 will basically not be myopic by the age of 15, even if the subsequent rate of hyperopia reserve consumption is different.
The development curve of hyperopia reserve in school-age children aged 6~15 years
At the same time, the hyperopia reserve of newborns usually decreases from 300 degrees to 150 degrees at the age of 3-9 months, and then basically stabilizes, and will not decline again until the age of 6, and finally completely stabilized after entering the orthometropia state at the age of 12-15 years.
Therefore, from the existing scientific conclusions, it is enough to check the farsightedness reserve once when the child is 6 years old, which is enough to cope with the subsequent development of vision.
And, from the point of view of accuracy and convenience, it makes more sense to review the axial length regularly. First, the eye axis does not need to be dilated, and routine examination can be done, which is more convenient, and the second is that the eye axis grows too fast, which is basically equal to the child's hyperopia reserve is consumed too fast and more accurate.
In other words, as long as the preschool eye axis growth rate is within a safe range (kindergarten children usually have an eye axis growth of less than 0.4 mm per year), it means that the child's hyperopia reserve is sufficient, and there is no need to worry about the risk of myopia in the next age development.
Fourth, if you don't do a farsightedness reserve test, is there any other necessary test to help prevent myopia in children?
0-3 years old: Screening for eye diseases, such as congenital cataracts, congenital sagging of the upper face, etc.
At this stage, the child's cooperation and understanding are relatively low, and the vision screener can be used to check the risk of other eye diseases such as amblyopia.
If the results of the vision screener are abnormal, take your child to the eye doctor and ask the doctor to give a more professional evaluation and judgment.
From the age of 3, a comprehensive eye screening (including eye axis, corneal curvature, etc.) should be carried out, and the child's exclusive eye health record should be established, and the examination should be carried out every six months to one year to dynamically monitor the problems in the process of eye development.
In addition, ensuring that children have enough time for outdoor activities and avoiding bad eye habits can well preserve the reserve of farsightedness and reduce the risk of myopia.
(1) Do not touch mobile phones, tablets and other electronic screens too early: it is not only harmful to eye development, but also not good for children's ability to communicate with others;
(2) 20-20-20 principle: each time you look at the electronic screen, the distance should be more than 20 feet (about 6 meters), the time should not exceed 20 minutes, and the interval between breaks should be more than 20 seconds;
(3) Ensure adequate sleep: 10 hours of sleep for primary school students, 9 hours for junior high school students, and 8 hours for high school students. Sleep can give the eyes a good rest, relieve eye fatigue, and reduce the risk of eye axis growth.
(4) Try to ensure more than 2 hours of outdoor activity time every day.