Topical Pilocarpine 1% administration failed to produce papillary constriction in a patient who had large dilated pupil. What could be most probable reason

C i.e. Pharmacological blockade Pilocarpine 1% is a sufficient miotic dose for any eye, but a sphincter with all its cholinergic receptor blockade by atropine or tropicamide (i.e. eye with pharmacological blockade) does not constrict with pilocarpine 1%. So fixed, dilated pupil d/t atropine (pharmacological blockade) can be differentiated with confidence from an innervation palsy by its tendency to resist the miotic effects of cholinergic drops such as pilocarpine. RAPD (Marcus Gunn pupil) is most characteristic of lesions in ipsilateral optic nerve. And when light is moved from normal to affected eye (while performing swinging flash light-test) in RAPD, there is dilation of both pupilsQ. Argyll Robeson pupil refers to bilaterally small miotic irregular pupil with light-near dissociation phenomenonQ. i.e. with absent light reflex (both direct and consensual) and normal pupillary constriction (during accommodation and convergence/ near reflex). Features Adie's Pupil ARP Lesion site Ciliary ganglia; usually in young women with absent knee jerk Internuncial neurons b/w pretectal (midbrain) & EW nucleus Vision Good Good Laterality Often unilateral Almost always bilateral Pupil Dilated slightly Miosis (constricted) Light reflex (Direct & Consensual) Delayed, slight (poor)/vermiform or absent Absent (Lost)Q Near reflex (Accommodation/ Convergence) Tonic (sluggish with long latent period & unduly sustained with affected pupil smaller than fellow) Brisk / Normal Effect of Atropine Mydriasis (dilates well) Does not dilate fully (no myclriasis) Miotic Constrict with weak solution Constrict