Whether or not you need to do dilation for a myopia test should depend on the age of the patient and the timing of the test. Usually, teenage patients or adults who are having their first optometry test are recommended to have their pupils dilated for a better understanding of the refractive state. After the pupil is dilated, the ciliary muscle can remain relaxed, and the patient’s fundus status can be more clearly observed, so that the refractive error can be more accurately understood. If the optometry is performed without dilating the pupils, the number of diopters detected tends to be biased towards myopia. Adolescent patients are prone to pseudomyopia after overuse of the eyes, if the pupil is not dilated, it is likely to be corrected according to the true myopia. Adults who undergo optometry for the first time, in order to clarify the refractive error and facilitate the prescription of glasses, it is recommended to dilate the pupils during the test in order to understand the true refractive state. For adults, if they need to have myopia tests in the future, they can choose whether to have the pupil dilated or not according to their own specific conditions and under the guidance of their physicians. Whether or not to dilate the pupils during the myopia checkup will be determined by the professional doctor according to your age and the need for prescription glasses.