About tropicamideanticholinergic (muscarinic blocker), ophthalmic agent, mydriatic, cycloplegic.mechanism of action of tropicamidetropicamide is a muscarinic receptor blocker. it nonselectively inhibits the muscarinic actions of acetylcholine. tropicamide blocks the muscarinic receptors in the muscles of the eye which are involved in controlling the pupil size and the shape of the lens. tropicamide blocks the cholinergic nerves supplying the smooth muscles of iris and produces mydriasis. it also causes paralysis of ciliary muscle and produces a tightening of the suspensory ligament and results in flattening of the lens and a consequent increase in focal length. because of paralysis of muscle cannot constrict the pupils for viewing near object or prevents the eye from accommodating for near vision (cycloplegia). tropicamide is given as eye drops to dilate the pupil and relax the lens so that eye examinations can be carried out thoroughly. it is often used to aid eye examinations