This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Toxicology, Subject name: Forensic Medicine
Pinpoint pupil is seen in: 
Select and explain. 
A. Organophosphorous poisoning, B. Opium poisoning, C. Dhatura poisoning, D. Barbiturate poisoning
B: Opium poisoning
Answer: B: Opium poisoning 
Explanation: Ans: b (Opium poisoning) Ref: Reddy, 21st ed,p. 506Pupil is typically pin point in opium poisoning. Pupil is constricted in organophosphorous poisoning also but it is not typically pin point.Causes of constricted pupilCauses of dilated pupil1. Organophosphorous1. Acute alcohol ingestion2. Opium2. Dhatura3. Formaldehyde3. Atropine4. Alcoholic coma4. Barbiturate poisoning (Late stage)5. Carbamate5. Organochlorine(Endrin)6. Phenol