What can cause my pupils to change size?

When you come in for your comprehensive eye examination it is common to have your eyes dilated to help the eye doctor to see into the back of your eyes to check the health.  This is done with specific eye medicated drops.  How these drops work is that they will react with the dilation muscle fibers of the pupil to increase their use and decrease the constriction muscle fibers of the pupil and in turn this creates a dilated pupil.  There are a few other things that can cause the size of the pupil to change, specifically to dilate (increase in size) or constrict (decrease in size).  For this subject we will focus on drugs and alcohol and how they affect the pupil size.

To start, we will look at what drugs can dilate the pupil.  Any drug that is a stimulant to the pupil muscle fibers can cause the pupil to dilate.  The most common drugs include Amphetamine, Methamphetamine, Cocaine or hallucinogenic mushrooms.  All these drugs act on the specific pupillary muscle fibers that open the pupil.  When taking these drugs you have a much greater concentration of cells to dilate the pupil than to constrict so the dilation cells win out and the pupils will dilate.

The opposite reaction will occur when you take drugs or alcohol that is a depressant.  Some of these drugs include Heroin, Oxycodone, Morphine, and Fentanyl along with copious amounts of alcohol.  They will act on the constriction pupillary fibers and overtake the dilation fibers and will decrease the size of the pupil sometimes to a pin point.

As part of a sobriety check, police or EMT’s will check pupil function to see if your pupils react normally or if they are dilated or constricted.  This in turn can help them decide if medical attention is needed or if you are not safe to be operating a motor vehicle.

People who take Flomax type drugs to help urinary retention also have pupil changes that affect cataract surgery.  If you take any of these medications tell your doctor and if you are concerned about your pupil size, call us at (860) 233-2020.