Dilation of the pupil refers to the technique of instilling eye drops which temporarily make your pupils larger. Dilating drops work on one of two principles:  they either stimulate the iris muscle that opens the pupil , or prevent action of the iris muscle that closes the pupil.  After the drops take effect, your doctor can get a much better view of your retina, optic nerve and vessels in the back of the eye.  This is a very important part of your preventative eye care as well as some eye surgeries.  From this simple step, we are able to gather a lot of important information about your eyes.