Doctors recommend that children undergo "mydriasis eye examination" and parents do not need to worry or resist

When going to an ophthalmology department or optometry center for a checkup, the doctor often recommends that children undergo "mydriasis refraction test". Many parents are worried or even resist this because they do not understand the principles and necessity behind it.

First, let's take a look at what "mydriasis" is. It is the use of drugs to dilate the pupil. As shown in the following figure.

Why do we need to “dilate the pupil”?

In fact, the real purpose of mydriasis is not to enlarge the pupil, but to relax the "regulatory mechanism" of the eye.

What is the adjustment mechanism of the eye?

The pupil is a round hole in the center of the iris. Behind the iris, there is a structure called the "ciliary body", which is the secret of the zoom function of the "camera" of the eye. The ciliary body pulls the elastic lens through the lens suspensory ligament. When the eyes look at distant objects, the ciliary muscles are in a relaxed state, which tightens the lens suspensory ligament and makes the lens flatter. When we look at something close, the eye's adjustment mechanism will automatically start: the ciliary muscles tighten and the pupil shrinks. At this time, the lens suspensory ligament relaxes, and the lens becomes "rounder" due to its own elasticity, so that we can see clearly at close range.

In children and adolescents, this ability to adjust is far greater than that of adults. If you do an eye test without dilating the pupil, the result is likely to be the result of the eyes being in a state of strong adjustment; after dilating the pupil, the ciliary muscle is paralyzed, the adjustment mechanism disappears, and the measured eye test result is a more realistic refractive state of the child's eyes.

This is why many children have their myopia measured by hundreds of degrees when they have their eyes tested directly, but when they are tested again after dilating their pupils, their myopia is more than 100 degrees lower or even gone. This is the origin of the so-called pseudomyopia. "Mydriatic drugs" are just a colloquial term, and the official name is "ciliary muscle paralytics". Pupil dilation is an inevitable consequence of using this type of drug, not the purpose.

Why don’t eyeglass stores dilate children’s pupils when fitting glasses?

It's very simple, they don't have the qualifications. Ciliary muscle paralytics are prescription drugs, and only doctors can prescribe and use them. Most optical shops don't have ophthalmologists or optometrists, so of course they can't use ciliary muscle paralytics to dilate the pupils of children.

Is mydriasis safe?

As long as it is used under the guidance of a doctor, there is nothing to worry about. Some children may be more sensitive to light in strong light because of their dilated pupils. They should avoid going out in strong sunlight or wear sunglasses.

If this article is helpful to you, you are welcome to share it with other parents. Maybe they also need it. Thank you.

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About Dr. Jingcai: The creators of Dr. Jingcai's popular science content all have a professional background in ophthalmology, a master's degree or above, and are former ophthalmologists. For some popular science content with a higher degree of professionalism, we will also invite working ophthalmologists and optometry experts to review and check it, striving to be responsible for the accuracy of the content and avoid misleading readers.