The essence of dilated optometry is to relax the fatigue caused by the excessive tension of the eye muscles over a long period of time, so as to obtain the true refractive state of the eye. Pupil dilation is the application of drugs to completely paralyze the ciliary muscle of the eye, losing the regulation of optometry. This is mainly because of the strong adjustment of the eyes of adolescents, if the pupil is not dilated, the regulation of the ciliary muscle can make the lens convex, refractive power enhancement, can not be adjusted myopia that is the so-called pseudo-myopia component is removed, which affects the accuracy of the results. Therefore, dilated optometry is necessary for young myopic patients. Children under the age of 18 who are getting their first prescription must have their pupils dilated. This is because they are likely to have pseudomyopia, (i.e., eye muscle tension caused by prolonged close study, but which can return to normal after a period of rest). If the pupils are dilated and then optometrically examined, the degree will be more accurate. Teenagers’ myopia is mainly caused by prolonged, close-distance, inappropriate use of the eyes. Especially in reading, writing, like to put the eyes very close to the eye, the eye’s regulation is strengthened, long dilated pupil optometry is the essence of relaxation due to the eye muscles for a long time, caused by eye distension, vision loss, the so-called spasmodic regulation, if the pupil dilated in the optometry, the ciliary muscle regulation can be made to the lens convex, refractive power increased, resulting in myopia deepened. The error of optometry will be very large. Therefore, when young people suffer from myopia, it is necessary to dilate the pupils when dispensing glasses. Children with hyperopia should also have their pupils dilated before getting a prescription. This is because children with hyperopia are over-adjusted, and many of them also have amblyopia and strabismus. Without dilating the pupils, it is difficult to know the true amount of hyperopia, and the prescription may be low, which is not enough to correct amblyopia and strabismus. Generally speaking, slow pupil dilation takes longer (about 21 days), but the effect is also better. This method is more suitable for younger children and those with hyperopia and amblyopia. Rapid dilation is quick (around 1 day). This method is suitable for children in general. It will not interfere with your child’s normal studies, as long as you take two days out of your schedule. Don’t worry if your child feels afraid of light or has difficulty seeing near objects after dilating his or her pupils. These symptoms are normal, and after a period of rest, they will be fine. The effect of the dilator causes paralysis of the ciliary muscle and dilation of the pupil, which can lead to photophobia and blurred vision. Rapid dilators wear off in 6 to 8 hours and the pupil returns to its original size. Slow dilators, i.e. atropine, may take 2 to 3 weeks to wear off. A small number of people who use atropine to dilate their pupils may experience symptoms such as redness, dryness of the mouth, dizziness, and panic attacks. Dilators are contraindicated in patients with glaucoma.