This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Neuro-Ophthalmology, Subject name: Ophthalmology
Adei's atonic pupil is due to 
Select and explain. 
A. Loss of sympathetic nerve supply, B. Loss of parasympathetic nerve supply, C. Vascular ischaemia, D. Infective neuritis
B: Loss of parasympathetic nerve supply
Answer: B: Loss of parasympathetic nerve supply 
Explanation: (B) (Loss of parasympathetic nerve supply) (313- Khurana 5th)ADIE'S TONIC PUPIL - caused by post ganglionic parasympathetic pupillo motor damage* Usually unilateral associated with absent knee jerk, common in young woman* Reaction to light is absent and to near reflex is very slow and tonicComparison bwtween Argyll-Robertson pupil and Adie's pupilFeaturesARPAdie' pupilVisionGoodGoodPupilConstrictedDilated (Anisocoria)LateralityBilateral, may be unilateralUnilateral, may become bilateralEffect of illuminationNilLarger in bright lightLight reflex (Direct and consensualAbsentAbsent /poorNear reflex (Accomodation)BriskTonicAtropineNo mydriasisMydriasisMioticConstrictConstrict with, very weak solutionLesionPretectalCiliary ganglionARP- first described in neuro-syphilis, but this may be seen in several conditions affecting the midbrain including Encephalitis, CVA, M.S etcHutchinson's pupil- developed after the head injury (H tor H)There is widely dilated immobile pupil on the same side as the head injury. Both the direct and the concensual reflexes to light are lost