Pupil dilatation is a term used in ophthalmology, often used in preparation for optometry or fundus examination, using drugs to bring the eye’s regulation to a resting state while the pupil dilates and the retinal light intake increases. Commonly used drugs for pupil dilation 1. 1% atropine eye drops, preferred for optometry in children under 10 years of age, two to three drops a day, for three days, and then optometry. Atropine eye ointment dilates the pupil for children’s myopia also has a certain therapeutic effect. Regular use of low concentrations of atropine eye drops can regulate the state of the ciliary muscle and reduce the deepening of myopia. 2, 0.5% compound tropicamide eye drops, suitable for children, adolescents or adults over 10 years old. Take 1 drop every 5 minutes, 4 times in a row, and have a medical optometry after 30 minutes of rest. The famous optometrist in China, Professor Zhu Renyuan, believes that 85% of people can use 0.5% tropicamide eye drops for pupil dilatation, and some teenagers with poor eyesight have had this experience: randomly with a pair of glasses, the result is “the more you wear the deeper”. The hospital’s ophthalmology department will ask for an optometry after the doctor’s examination, and it must be done with dilated pupils. Many people feel that the dilated eye exam takes a long time, and that their eyes are uncomfortable and hazy after the dilated eye exam. So, why do adolescents need to have their eyes examined? The purpose of optometry is to determine the refractive state of the eyes, the presence of refractive error, the type of refractive error and its degree. Based on the results of the eye exam, the number of glasses will be decided, so whether the eye exam is accurate and reliable is directly related to the correction effect. Not only that, any disease of vision loss can be diagnosed clearly only when refractive error is excluded or corrected. Therefore, optometry is an important examination tool in the medical field. Dilated optometry is the application of medication to paralyze the ciliary muscles of the eye and dilate the pupil, both of which are altered, allowing the eye to be examined in a state of quiet rest. The advantage of dilated optometry is that it is accurate. Doctors often require children to undergo dilated optometry, but why is this? This is because children’s eyes are highly adjustable, and the results of optometry are inaccurate under the influence of adjustment, often leading to overcorrection of myopia, i.e., the prescription is larger than the actual number of glasses to be worn. A pair of overcorrected glasses can be damaging to a child’s eyes. The dilated eye exam eliminates the interference of adjustment, making the exam more objective and the prescription accurate. Most of the myopia that occurs in adolescents starts with “pseudomyopia” caused by bad habits of using the eyes at close distances and becomes true myopia, and some of them have “pseudomyopia” added to the real axial myopia. In short, the results of optometry are very inaccurate under the influence of adjustment, and if the phenomenon of “pseudomyopia” is also treated as true myopia and corrected with lenses, it will lead to rapid myopia, and dilated optometry can avoid this drawback. Farsightedness also requires dilated eye examinations. Because of the short axis of the eye, farsightedness requires the use of the eye’s adjustment, not to mention the nearness, but also the distance. Therefore, in order to see objects at any distance, farsighted eyes need to contract the ciliary muscle to enhance refractive power. If the ciliary muscle is not paralyzed, the regulation will mask part of the farsightedness and make it impossible to detect. The younger the patient, the more vigorous the accommodation, and the higher the degree hidden. Without dilated pupils, it is impossible to detect the full extent of hyperopia. As we know, the purpose of glasses for hyperopic children is to correct vision and prevent or treat refractive amblyopia, and to correct eye position, i.e., to treat adjusted internal strabismus and prevent or treat strabismic amblyopia. All of this must be done to find out the exact degree of hyperopia, so children with hyperopia must be dilated for optometry. Generally speaking, adults with simple myopia can obtain accurate lenses for optimal vision using either the direct trial method or the computerized examination method. However, adults with high hyperopia and astigmatism often have difficulty in determining which is the best lens because it is not easy to obtain the best visual acuity by trial lenses, and should also have their pupils dilated. Therefore, the following groups of people must have their pupils dilated: 1. Children younger than 15 years of age need to have their pupils dilated. 2. Children younger than 12 years old must have their pupils dilated. 3. Adults, if they are visually fatigued, must have their pupils dilated. 4.For internal strabismus, the nature of the strabismus can be identified by complete paralysis of the ciliary muscle, whether it is a primary or secondary strabismus. This provides an indispensable clinical medical basis for choosing a treatment plan. Because primary strabismus often requires surgical intervention, while secondary strabismus can be treated with glasses only. Many parents often ask us if it will damage their child’s eyes if they are afraid of light and cannot read for most of the month after the atropine dilated eye exam. This is nothing to worry about. Except for some specific eye diseases such as primary angle-closure glaucoma, any other necessary dilatation will only facilitate the doctor’s examination in order to get accurate results and will not be harmful to the eyes. Dilating the pupil completely relaxes the ciliary muscle, so that the eye’s regulation is completely relaxed, and the eye can only see far away and blurred near. It is also easy for the doctor to conduct a comprehensive examination of the eye, such as the fundus, after dilating the pupil. Atropine is a ciliary muscle paralyzing agent, mostly used in 0.5% pediatric optometry with high accuracy. Short-term side effects are, blurred vision, recovering 3 weeks after discontinuation. A few children may have obvious symptoms such as flushing of the face, thirst, fever, headache, nausea, vomiting, constipation, hallucinations, spasms, excitement, and eyelid edema after pupil dilatation, which are considered to be adverse reactions to Atropine. Once this occurs, the drug should be stopped immediately or consult If this happens, stop the drug immediately or consult an ophthalmologist. It is very unlikely that this phenomenon will occur with topical ophthalmic medications in clinical practice. After applying the ophthalmic ointment to the eye, gently compressing the inner corner of the eye for a few minutes can prevent the ophthalmic drug from being absorbed through the mucous membrane and reduce the systemic reaction of the drug, and when ordering atropine ophthalmic ointment, just order a small grain of rice, not too much.