Big Pupils

Causes Of Big Pupils

What actually makes those small black circles in the middle of your eyes turn into really big pupils?  There are actually quite a few causes, some of which are controllable, others that are not.  The pupil is an opening that permits light to penetrate your eyes.  When you have big pupils this means that your eyes are dilated, allowing more light to enter.  You can actually test this theory by standing in front of a mirror in a dark room.  When you turn the light on, you will notice your pupils decrease in size.  Therefore, if you come in from outside or from a bright location, into a room with very dim lighting, you will end up with big pupils.



It is quite easy to notice someone on drugs by the size of their pupils.  Illegal substances and stimulants such as cocaine, mescaline, peyote, methamphetamine, mushrooms, LSD, marijuana and ecstasy will all leave you with some pretty big pupils.  Your central nervous system is excited by these drugs and mixed signals are sent to your brain.  These mixed signals are what causes euphoria, dilated pupils, mood swings, irrational behavior and an increased heart rate.


Your eyes truly reflect the stimulation that they receive from looking at someone.  Without you knowing, or even being able to control the action, your brain sends stimulating messages to your eyes based on what you are looking at.  It is reported that a man's eyes can dilate up to 30 percent when he is shown pictures of a beautiful woman.


Big pupils are often caused by epilepsy or other types of seizure disorders.  When muscle spasms, staring and unconsciousness occurs, the pupils grow very wide and are not responsive to stimuli such as light.  Seizures are typically caused by hyperexcitable nerve cells that misfire, sending the brain inappropriate signals.


Chemical and plant poisons are common causes for pupil dilation.  Toxic chemicals such as jet fuel and chloroform have this effect as does the bark of a black locust tree.  If you feel that you may have been exposed to a chemical and you have big pupils, you need to seek medical attention immediately and you should not attempt to drive.


As the message delivery system in your brain is interfered with, your pupils will dilate.  Typically, a person who experiences a blow to the head or a fall where they hit their head on the ground or an object, will display dilated pupils.  This causes light sensitivity as well as other vision problems.


These medicinal eye drops are administered by an eye doctor to complete an exam by observing the pupils more deeply and testing their response to light.  It is usually recommended that when you have to receive mydriatics, to wear your sunglasses for at least an hour after they have been put in your eyes, while your eyes are recovering.  If you attempt seeing in bright conditions with no protection, your eyes can get very stressed which can ultimately cause damage.



Aniridia is an iris abnormality where there is either no iris or it is not completely developed.  It is a rare condition that results in extreme light sensitivity because the pupil is not able to constrict.  Alternatively, coloboma of the iris is a similar condition that creates a permanent keyhole appearance of the pupil that also increases sensitivity.


This abnormal pupil constriction often results from medication toxicity.  Pilocarpine, which is a glaucoma medication, lowers ocular pressure which can cause this condition.  Having small pupils because of miosis can impact your vision because not a lot of light gets into your eyes.