What type of drugs are used to cause contraction of the iris sphincter muscle?

Miotics are the specific type of drugs that cause contraction of the iris sphincter muscle. These medications work by stimulating the parasympathetic nervous system, which leads to the contraction of the smooth muscle of the iris. When the iris sphincter muscle contracts, it results in miosis, which is the constriction of the pupil. This is particularly useful in situations such as treating glaucoma, where increasing outflow of aqueous humor is beneficial.

In contrast, mydriatics are agents that cause dilation of the pupil and are used for different purposes, including facilitating examination of the retina. Myodilating agents are not a recognized category of drugs specifically associated with iris muscle dynamics, and analgesics are pain relief medications that do not have an effect on iris contraction or dilation. Therefore, the definition and function of miotics align perfectly with the question about inducing contraction of the iris sphincter muscle.