Pupil dilation is the enlargement of the pupil, which means that the diameter of the pupil increases. Pupil dilation can be caused by a variety of reasons, such as external light stimulation, the application of dilating drugs, eye trauma, neurological disorders and so on.
Under normal circumstances, the diameter of the pupil is between 2 and 4 millimeters. In bright environments, the diameter of the pupil will be appropriately narrowed to avoid glare, while in dim environments, the diameter of the pupil will be appropriately enlarged, so that you can see the dark scene clearly.
Dilating drugs in the eye can also cause pupil dilation, commonly used are compound tropicamide eye drops, atropine eye drops, etc., which are mainly used for the treatment of iridocyclitis, as well as dilating the pupil for optometry, dilating the pupil to check the fundus of the eye, and so on.
Trauma to the eye causing paralysis of the pupil sphincter can also cause pupil dilation, which is called traumatic dilation.
Neurological disorders can also cause dilation, such as cerebral infarction causing damage to the nucleus accumbens.
Patients with dilated pupils should not be overly concerned if the dilation is caused by external light. If there is a history of trauma or other medical conditions, it is necessary to go to the hospital in time to find out the cause.