Also called mydriasis, the dilation of the pupils results in an enlargement of the diameter of the pupil, this small black circle located in the center of the eye through which the light enters.

Usually benign, pupil dilation can still be a sign of serious damage, such as brain damage or a tumor. Also, it is advisable to consult a doctor who will be able to establish in a precise way a diagnosis aiming at best treating the problem. Note that only one eye or both eyes can be affected by a dilation of pupil (s).

There are many factors causing dilation of the pupils. The simple variation of the luminosity causes dilation of the pupils. This is a normal reaction to dim light. In a dark place, the pupils dilate spontaneously to allow the entry of a maximum of light and thus increase the capacities of vision.

But this phenomenon can also occur when the brightness does not change. These include:

• intense emotion: when mydriasis is not due to a change in light and is not pathological, it can be a sign of attraction to another person

• administration of drugs such as atropine or mydriatic eye drops (eye drops used to dilate the pupil) by the ophthalmologist to better observe the back of the eye

• excessive alcohol consumption

• taking drugs, such as cocaine, cannabis, amphetamines or LSD

• taking certain medications, such as antidepressants

• benzene or chloroform poisoning

• ocular parasympathetic nerve palsy following trauma

• significant cerebral suffering: cerebral aneurysm, cerebral edema

• cardio-respiratory arrest

Note that only one pupil can be dilated. In this case, it could be:

• a paralysis of the sphincter, the muscle responsible for the contraction of the pupil. This makes it impossible for the pupil to contract

• spasms of the dilator, the muscle responsible for the dilation of the pupil

• compression by a tumor or intracerebral hematoma

Generally speaking, a person with mydriasis is constantly dazzled and has blurred vision.

The consequences then vary depending on the cause of the mydriasis. For example, if the dilation of the pupils is caused by an injury or damage to the brain, the consequences can be serious. Among some of these complications:

• a comma

• a speech problem

• vision deficit

• or even paralysis

To stop having dilated pupils, you must directly treat the cause.

Note that the treatment can simply consist of the application of miotic eye drops. They have the effect of causing miosis, that is to say a decrease in the diameter of the pupil (the opposite of mydriasis).

In any event, the doctor will observe the pupils and perform a pupillary reflex test in order to assess the seriousness of the problem and in particular the neurological state of the patient.