This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Pupillary Reflexes and their Abnormalities, Subject name: Ophthalmology
In a case of anisocoria, when 1% pilocarpine le is instilled into the eye with abnormally dilated pupil, no response occurs. Cause of anisocoria may be: 
Select and explain. 
A. Adie's pupil, B. Horner's syndrome, C. Pharmacological blockage, D. Uncal herniation
C: Pharmacological blockage
Answer: C: Pharmacological blockage 
Explanation: Ans is 'c' i.e. Pharmacological blockage Anisocoria (inequality of pupillary size) implies disease of the efferent (motor) nerve of the light reflex, iris or muscles of the pupil.If, on application of pilocarpine 1% in each eye, the affected pupil reacts little or not at all and the unaffected pupil constricts normally, the pupil is not dilated because of innervation problems but because of a problem in the sphincter muscle, itself. Non-neuronal causes of mydriasis are:Anticholinergic mydriasis (e.g., scopolamine (hyoscine), cyclopentolate, atropine).Traumatic iridoplegia (sphincter rupture, pigment dispersion, angle recession).Angle-closure glaucoma (ischemia of the iris sphincter).Fixed pupil after anterior segment surgery.Bound down iris (synechia) after iritis."