Pilocarpine causes:
Active miosis
Active mydriasis
Passive miosis
Passive mydriasis
Ans. A. Active miosisTwo types of muscle are present in the eyes. Circular muscle which have M3 receptor and radial muscle which have Alpha 1 receptor on them. When M3 is stimulated, it causes contraction of circular muscle leading to active miosis. When alpha 1 is stimulated, it causes contraction of radial muscle leading to active mydriasis. On the other hand, if M3 is blocked, it leads to passive mydriasis and blockade of alpha 1 receptor leads to passive miosis. Pilocarpine being cholinergic drug stimulates M3 receptor and thus causing active miosis.
A.N.S.