Under normal circumstances, the diameter of the adult pupil is about 2.5-3 mm. If the pupil is abnormally dilated, it can be seen in the following cases: 1) trauma or surgery that causes damage to the pupillary sphincter, resulting in pupil dilation; 2) ankylosing pupils, where the pupil is irregularly dilated and the reflex to light is blunted; 3) in actinic nerve palsy, which is usually accompanied by extraocular This condition is usually accompanied by extraocular muscle paralysis or ptosis; 4. It is caused by the use of pupil-dilating medications, such as tropicamide or atropine drops; 5. It is usually caused by a physiological pupil inequality, which does not require treatment as long as the diameter of the two eyes is less than 2 mm.