How can we differentiate clinically between the action of the anti-cholinergic drug (atropine) , and the sympathomimmetic drugs regarding the action on the Eye(Mydriasis)?
The mydriatic action of atropine is due to paralysis of the parasympathetic nerve supply to the iris so it is associated with loss of the reflexes that depend on this nerves e.g. light reflex i.e. directing a light source to the cornea will not lead to miosis. The mydriatic action of epinephrine is due to activation of the sympathetic nerve supply to the eye so it is not associated with loss of the light reflex.
