Once astigmatism is detected, parents often feel at a loss and hope to find the cause that leads to their child’s astigmatism. For example, in the comment section of Does a child need to sleep in a completely dark environment at night, without any light?, many parents are worried whether the light around their child at night could cause astigmatism?
So, today we will solve everyone’s confusion about astigmatism through an article, and after reading, we will not be so anxious.
What is astigmatism?
If the lens is a perfect spherical shape with a constant radius of curvature, then the astigmatism degree is 0. Light passing through this lens can focus on a single point, and the image is very clear.
Image from Refractive errors. Dtsch Arztebl Int 2016; 113: 693–702
If the lens is not a perfect spherical shape and the shape is irregular, astigmatism will form. In most cases, the eyeball with astigmatism is an ellipsoid, and if the ellipsoid is closer to the shape of an olive, it is speculated that the degree of astigmatism is also higher.
Light passing through such a lens cannot focus on a single point, and the image will be unclear. And whether looking at distant or close objects, this blur will continue to exist.
Most people have astigmatism of less than 50 degrees, this degree of astigmatism has little effect on vision, also known as “physiological astigmatism”; astigmatism of more than 100 degrees often has varying degrees of impact on vision.
Can a child’s astigmatism be caused by having lights on around them while sleeping?
Unlike myopia, environmental factors have a very, very small impact on the occurrence and development of astigmatism, which means that it is not caused by a lack of outdoor activities or too much close-up eye use.
The real causes of astigmatism include:
One’s own corneal morphology, corneal biomechanical characteristics, lens shape, etc., are related to heredity and genes.
Such as congenital ptosis, severe entropion, large central chalazia, persistent blepharospasm, etc., these factors cause pressure on the eyeball from the eyelids, leading to irregular corneal morphology.
So, having lights on around a child while they sleep will not cause astigmatism.
What are the impacts of astigmatism?
The impacts of astigmatism are mainly as follows:
Simply put, it means not being able to see clearly.
French philosopher Maurice once said: “Vision is the way the brain touches the world.” If you can’t see clearly, then humans cannot receive external information well, and life, learning, or work will be affected.
When the eyes do not see clearly, they will feel uncomfortable, the eyes will feel dry, swollen, tired, and severe cases can even cause headaches. These are all manifestations of visual fatigue.
The higher the degree of astigmatism, the higher the risk of amblyopia.
Humans are binocular visual animals. When the images seen by both eyes are clear, the two eyes can work together harmonically.
When the astigmatism degrees of both eyes are significantly different, the clarity of the things seen will be different, and our brain will find it difficult to integrate these two images. It may lead to monocular suppression or abnormalities in accommodation and convergence functions, which also affects the binocular coordination in seeing things.
Why are children with high astigmatism prone to amblyopia?
Under normal circumstances, the image on the retina is clear, and there will be clear image information repeatedly stimulating our visual information processing system (the central nervous system, also known as the brain), so that visual functions can develop normally.
However, for children with high astigmatism, the image on the retina is continuously unclear (both distant and near), and the visual information processing system lacks the stimulation of clear images. Over time, the development of the visual system will lag behind.
At this time, even if you wear the right glasses, the imaging on the retina is clear, but the processing ability of the visual information center does not meet the standard, and children still cannot recognize enough visual information. The eyes can see, but the brain cannot recognize, which will manifest as corrected vision (also known as the best vision that can be seen with glasses) is low, which is amblyopia.
We can understand it as not learning well when we should learn, and we will be illiterate.
Can astigmatism be prevented?
Since astigmatism mainly comes from congenital factors, there is no way to prevent it. Even increasing outdoor activities in natural light and avoiding prolonged close-up eye use cannot prevent the occurrence of astigmatism. Foods and medications (such as the popular lutein) are even less helpful.
Will the degree of astigmatism increase over time?
Generally not.
We all know that before adulthood, a child’s eye axis will continue to grow, so the degree of myopia may keep increasing. Poor eye habits and less outdoor activity can lead to faster eye axis growth and faster degree increase.
Astigmatism is different~
Most of astigmatism comes from the morphology of the cornea (the lens will also have a small impact).
● Before the age of 3, the child’s eyeball is in a stage of rapid development. With the development of the eyeball, in most cases, the degree of astigmatism will gradually decrease.
● Around the age of 4, the development of the cornea will slow down or basically stop. So, children over 4 years old generally will not have significant changes in astigmatism, and it will not keep increasing rapidly.
If the re-examination finds that the degree of astigmatism keeps increasing and the corneal curvature changes significantly, it is necessary to consider whether there is a corneal disease (such as keratoconus, of course, this situation is relatively rare).
For middle-aged and elderly people, the situation is different. With age growth, presbyopia of the lens, and reduced eyelid tension, astigmatism may also slightly increase after the age of 40, and the axis of astigmatism will also change.
Image from Distribution of astigmatism as a function of age in an Australian population. Acta Ophthalmol. 2015 Aug;93(5):e377-e385.
Will outdoor activities increase and good eye habits lower the degree of astigmatism?
No. As mentioned earlier, the occurrence and development of astigmatism are unrelated to eye use. It is more due to congenital factors, not because of less outdoor activities or poor eye habits that astigmatism occurs; of course, it is also impossible to reduce the degree of astigmatism by increasing outdoor activities and maintaining good eye habits.
Of course, we are not helpless and do not need to do anything. We still need to maintain a large amount of outdoor activities and develop good eye habits to prevent children from not only having astigmatism but also growing their eye axis quickly, and eventually becoming highly myopic.
Do all astigmatism require wearing glasses?
Because astigmatism may affect children’s vision (i.e., not seeing things clearly without glasses), visual development (amblyopia), and the occurrence and development of myopia (fast eye axis growth), etc., if the degree of astigmatism is higher and there are more of the following situations:
The urgency of wearing glasses is stronger, especially for children with amblyopia, they must, must, must (important things are said three times) wear glasses.
If there are no above situations, and the child only has low-degree astigmatism with little effect on vision, it is also possible not to wear glasses and just observe closely.
Do astigmatism glasses need to be worn all the time?
If it is assessed that glasses are needed, then the prescribed astigmatism glasses need to be worn all day.
In addition to persisting in wearing glasses, it is also recommended not to forget regular re-examination. If subsequent re-examinations find that the child’s astigmatism degree has dropped to the normal range, and there are no other abnormalities, it is also possible to consider not wearing glasses.
Simply put –
● When the eyes develop to a point where the astigmatism degree is not high, and there is no significant impact on vision and visual development, and there is no need for glasses assistance, it is also possible to stop wearing glasses.
Finally, a little more to say, the purpose of wearing glasses for astigmatism is to assist and treat possible amblyopia; not to treat astigmatism or to reduce or eliminate the degree of astigmatism.
I hope the above content can answer most of the parents’ questions about astigmatism~
Finally, if your child is screened or examined to have astigmatism, it is recommended that we still take the child to see an ophthalmologist in time for a full assessment and professional advice~
References
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