mydriatikum

Mydriatikum is a pharmacologic agent used to induce mydriasis, the dilation of the pupil, in ophthalmology. It is typically applied as topical eye drops and serves to facilitate slit-lamp examination, retinal inspection, laser procedures, and preoperative pupil dilation for cataract surgery. Mydriatics may act by blocking the iris sphincter muscle (antimuscarinic or parasympatholytic agents) or by stimulating the iris dilator muscle (sympathomimetic agents); many regimens combine both mechanisms to achieve rapid and sufficiently sustained pupil dilation, often with some cycloplegia.

Common antimuscarinic mydriatics include tropicamide and cyclopentolate, which provide short- to intermediate-acting dilation. Atropine is a long-acting agent used less frequently due to its prolonged effect. Phenylephrine is a selective alpha-1 adrenergic agonist that dilates the pupil by stimulating the dilator muscle and can be used alone or with tropicamide for greater effect. Dosing and concentrations vary by agent and patient factors.

Clinical use typically involves one or more drops in the affected eye, with timing and repetition tailored to the procedure and patient age. Patients should expect light sensitivity and blurred distance vision for several hours after administration. Systemic effects are rare but can include tachycardia, hypertension, and restlessness, especially with higher doses or in susceptible individuals.

Contraindications include known hypersensitivity to the drug class and conditions associated with narrow-angle glaucoma, as mydriatics can precipitate angle-closure attacks. Caution is advised in cardiovascular disease, hypertension, thyroid disorders, or in very young children and elderly patients. Pregnancy and lactation require careful consideration of risks and benefits.