Mydriasis (extreme Pupil Dilation): Symptoms, Causes And Treatment
We know as mydriasis the phenomenon of widening of the pupils (pupil dilation), which can be caused by factors both internal and external to the body itself. It is the opposite process to miosis (the reduction in pupil size) and is generally a physiological response to light and brightness.
However, if it remains dilated even without the light stimulus, then it is surely no longer a physiological response and could be an indicator of the presence of diseases or pathological habits. Below we explain how the pupils work and What factors can cause its dilation, mydriasis
The pupils are the black circles located in the center of our eyes and their function is to pass light to the retina to form images. They are surrounded by the iris and cornea, and are composed of an opening that widens or contracts to allow light to pass through. Sometimes it widens to allow us better vision, and sometimes it contracts to protect us from excessively bright stimuli.
However, the pupils are activated as an automatic response to different factors (not just light), and the system that is responsible for controlling their activity is the autonomic nervous system, in turn divided into the sympathetic nervous system and the nervous system. parasympathetic.
When the reason for the widening of the pupil It is not only related to our physiology and our vision then mydriasis may be an indicator of the existence of a pathological condition, or it may indicate that some substance that alters the nervous system has recently been consumed.
Mydriasis is a natural and quite common phenomenon that helps us adequately perceive light when it is presented to us in large quantities. However, in some cases, mydriasis It is not caused by exposure to light but by other elements that also affect our body
Among the factors that change the size of the pupil causing mydriasis are some diseases and drug use. Below we will present
Pharmacological causes
As its name says, the pharmacological causes of mydriasis are those that are related to the use of drugs. For example, the use of anticholinergics increases dilation since these are substances that block the transmission of some chemicals to the eyes.
Another pharmacological cause is the recreational use of psychotropic substances, such as cocaine, ecstasy, hallucinogens, methamphetamines or THC. This is because these substances affect the serotonin receptors in the brain (depending on the type of drug, they increase or decrease its secretion), which generates dilation.
Medical causes
Medical causes are those that are related to surgical intervention that has among its effects the dilation of the pupils. For example, surgeries to treat brain trauma cause mydriasis because they increase pressure on the skull, which affects the eyes.
On the other hand, eye surgeries sometimes significantly damage the nerves that control the pupils or iris. Consequently, the pupils can adopt different ways of reacting to light.
Physiological and neurophysiological causes
The physiological and neurophysiological causes of mydriasis are those that are related to our biological or neuroanatomical functions. Specifically, they are causes related to how our brain and other related systems work.
The presence of high levels of oxytocin It can lead to a temporary condition of mydriasis. This is because oxytocin is the substance that is released when we exercise and when we interact with people, both physically and socially. It is also the substance that is released during childbirth.
Likewise, mydriasis is usually present during cranial nerve neuropathies, which are gradual damage to the nerves surrounding the eye. This affects the oculomotor system and the nerves responsible for widening or contracting the pupils.
For example, parasympathetic nerve palsies. Other causes related to this are strokes traumatic brain injuries, brain hernias or epilepsy.
Finally, one of the conditions that include mydriasis is Benign Unilateral Episode of Mydriasis (BEUM), which is a temporary condition of pupil dilation, generally accompanied by headaches and eye pain, sensitivity to light and blurry vision. It usually occurs, for example, during some migraine episodes.
Treatment and what to do
When faced with mydriasis, it is important to remain alert in case the dilation of the pupil continues for a prolonged period of time (if the light stimulus has disappeared or enough time has passed to adapt to it). In these cases it is important to consult a specialist doctor
As a treatment it is recommended Avoid the direct exposure to the sun, as well as avoiding driving. It is also advisable to use dark lenses (glasses) and avoid reading texts at a short distance. Doing the opposite of all these recommendations can cause mydriasis to remain and significantly affect our vision.
On the other hand, if it is an indicator of a pathological condition, the specialist could recommend surgical treatment.
