School is about to start, it will be too late if we don’t do this!!!

"Science Popularization China - Back to School Season" Special Issue No. 01

The children are about to return to school. For those children with vision problems, there is one thing they must not forget to do, and that is - eyesight testing .

This is because children, especially those in lower grades, usually need to undergo "slow mydriasis" during their eyesight test, which takes about 2-3 weeks to fully recover . If it is not done early, it will have some impact on their school life.

So why do children need to dilate their pupils when checking their myopia? And what are some good ways to prevent myopia? Let's talk about it today.

The "aperture" and "lens" in the eye

Let us first briefly introduce the structure of the eyeball before we can explain what mydriasis is.

There are two components in our eyeballs that are very similar to the parts in a camera lens. One is the iris , which is what we usually call the black pupil. There is a small hole in the center, which is the pupil. The iris and pupil are like the aperture of a camera. When the light is strong, the pupil will shrink a little to allow less light to pass through; when the light is weak, the pupil will open a little to allow sufficient light to enter the eye, making the eyes comfortable to see both light and dark.

Most Asians have brown irises.

The other is the lens , which is the most important "lens" in our eyes. However, when the camera focuses, it relies on changing the distance between the lens groups. Of course, the human eye cannot fit so many lenses. We rely on the adjustment of the ciliary muscles to change the bulge of the lens, thereby changing the refractive power of the lens to achieve focusing; in this way, the image formed inside the eye falls exactly on the retina, allowing the eyes to see clearly both far and near.

The upper part shows normal vision, and the lower part shows myopia. Image source: lasercollection

In most cases, myopia in adolescents is caused by the elongated distance between the front and back of the eyeball , which results in the image falling in front of the retina no matter how the ciliary muscle adjusts when the eyes look far away. This is myopia and should be corrected.

Why do children need to have their pupils dilated when having their eyes tested?

Mydriasis refers to a common ophthalmic diagnosis and treatment method in clinical practice. The common method is to drop eye drops containing paralytic agents into the eyes. In this way, the pupillary sphincter is paralyzed and becomes dilated, so the pupil dilates, which is also the origin of the name "mydriasis". After mydriasis, the pupil becomes larger, and it becomes easier to examine the structure of the fundus .

Copyright image, no permission to reprint

Another important function of mydriasis is to paralyze the ciliary muscle. When testing children's eyes, mydriasis is used to paralyze the ciliary muscle so that it can relax. This is because the ciliary muscle of children is too "strong" and often in a contracted state, which will make the lens too convex, leading to the formation of pseudomyopia.

If the pupil is not dilated during optometry, it is called small pupil optometry, which may lead to deviation in the results - the child is originally in emmetropia or mild myopia, and the degree of myopia may be too large during small pupil optometry. If the child is fitted with glasses based on this result, he may experience dizziness, visual fatigue and other discomforts. Mydriasis optometry is to remove the pseudomyopia under the small pupil.

Since children's ciliary muscles have a strong ability to adjust their contraction, it is necessary to use drugs with stronger paralytic effects, such as atropine, to dilate the pupil. In this way, the recovery time is relatively long, and it takes 2-3 weeks. This is what we usually call "slow dilation". The enlarged pupil and paralysis of the ciliary muscles will allow more light to enter the eye and reduce the adjustment ability of the lens. In this way, the eyes will not be able to withstand light, and there will be many inconveniences in reading and writing. Therefore, this is why we need to remind everyone to prepare early and go for an eye test as soon as possible to avoid affecting their return to school after school starts.

Some parents may worry that if the pupils are dilated for several weeks, will the "drug strength" affect the health of their children? It is natural to care about children, but this is indeed a bit exaggerated. Because for most children, mydriasis refraction will only cause temporary photophobia, blurred vision and other problems, which are mainly caused by the dilation of the pupils and the failure of the ciliary muscle to adjust in a short period of time, and it is safe for the eyes themselves .

However, parents should be reminded that dilation should be done at a regular hospital , because dilation increases intraocular pressure, and regular hospitals can check and evaluate this. Otherwise, if the child's intraocular pressure is abnormal, dilation may bring certain risks.

To fight myopia, you can do these things

If a child is really nearsighted, of course he needs to have his pupils dilated, have his eyes tested, and have them corrected. But we can also do something to prevent myopia.

First, avoid long-term close-up use of the eyes . Ensure good lighting in the place where children study. At the same time, teach children the 20-20-20 method, that is, every 20 minutes of eye use, you should take a break and look at a place 20 feet (about 6 meters) or more away for 20 seconds. This can relax children's eyes and avoid fatigue.

In addition, you should also take your children out for more activities , ensuring that they spend 2 hours outdoors every day. This has two main benefits for the eyes. One is that you can often look far away outdoors, which helps relax your eyes. The other is that the strong light outdoors helps the retina secrete dopamine, which can slow down the development of myopia. It should be noted that children's eyes need the beautiful sunshine outdoors, but they do not need the ultraviolet rays that can harm the eyes. Therefore, you can prepare a sun hat for your child to avoid direct sunlight on the child's eyes.

Copyright image, no permission to reprint

Finally, there is one more very important point, which is that it is best to take your children for regular eye examinations from an early age, and understand your child’s hyperopia reserve, myopia development, etc. from an early age, so that you can respond earlier.

For children who already have myopia, currently proven methods that can effectively slow the progression of myopia include: OK glasses, low-concentration atropine, and myopic defocus glasses. This article will not go into detail on this topic, and you can refer to relevant popular science articles.

Author: Ding Zong

Reviewer: Jia Changkai, deputy chief physician, Xiamen Eye Center, Xiamen University

What other school content are you interested in?

Please leave us a message

The cover image and the images in this article are from the copyright gallery. The image content is not authorized for reprinting.