There are many causes for your pupils to become dilated. Some reasons include: illicit drugs, emotion, drug overdose, medication overdose, certain medications, certain eye drop medications, brain injury, stroke, brain tumor, coma, Adie's syndrome (causes pupils to react more slowly that any other), blindness, third nerve palsy, and eye nerve irritation. You can find more information here: http://www.wrongdiagnosis.com/symptoms/pupil_symptoms/causes.htm
