The size of the pupil adjusts automatically according to the amount of light from the outside world, and generally does not have a significant effect on vision. However, if the pupil size cannot be restored after dilation or reduction, it may cause vision loss. Under normal circumstances, the size of the pupil will be automatically adjusted according to the external light intensity, the pupil will become smaller when the light is strong, and the pupil will become larger when the light is weak, this is the self-protection of the eyes, and generally does not have a great impact on vision. However, if the pupil cannot be restored after enlargement, the eyes cannot block the intake of bright light, which will irritate the eyes and damage the retina, thus causing vision loss, making the eyes afraid of light, and easily leading to dry eyes. If the pupil cannot recover after shrinking, it will make the patient insensitive to light reflex, and the pupil size may also be different, which will cause low vision in serious cases. When the patient’s pupil size is abnormal, it is recommended to consult a doctor in time for diagnosis and treatment by a professional doctor.