Mydriatic activity

Mydriatic activity refers to the physiological process of pupil dilation, known as mydriasis, which is controlled by the balance of the autonomic nervous system's influence on the iris muscles. This activity is not a discrete molecular target but rather a pharmacological effect or clinical endpoint achieved by modulating specific receptors in the eye. It is primarily mediated through the antagonism of muscarinic acetylcholine receptors (parasympatholytics) in the iris sphincter muscle or the activation of alpha-1 adrenergic receptors (sympathomimetics) in the iris dilator muscle. In clinical practice, drugs that induce mydriatic activity are essential for diagnostic ophthalmic examinations, such as retinal imaging and fundoscopy, as they allow for a clearer view of the internal structures of the eye. Additionally, mydriatics are used therapeutically to manage inflammatory conditions like uveitis by preventing the formation of adhesions between the iris and the lens.

Other names

MydriasisPupillary dilationDilated pupil

Mydriatic activity is produced by either blocking the parasympathetic nerve supply to the iris sphincter muscle (via muscarinic receptor antagonism) or by stimulating the sympathetic nerve supply to the iris dilator muscle (via alpha-1 adrenergic receptor agonism).