11.2.3Parasympatholytic, Anticholinergic Drugs

One of the most commonly used drugs for dilation of the pupil is tropicamide. It is a short-acting drug used in the form of drops. Cyclopentolate, homatropine, scopolamine and atropine have much longer duration of action. As well as dilating the pupil, they all also relax the muscle fibers of the ciliary muscle. Some of them are used by anesthesiologists intravenously to treat bradycardia. Tricyclic (non-selective monoamine reuptake inhibitors) and tetracyclic antidepressants may dilate the pupil. Some histamine antagonists (some first-generation histamine 1 receptor blockers) have atropine-like effects.

ciliary body in chronic use and may induce anterior movement of the iris–ciliary body diaphragm, so narrowing an open angle.

Thickening of the lens may be induced by sulfa-based drugs or when changing from oral antidiabetics to insulin therapy. The antiepileptic drug topiramate can cause ciliary body edema, leading to relaxation of the zonules and thickening of the lens, choroidal detachment and supraciliary effusion.

In summary, be careful in eyes with higher hyperopia or a short axial length when dilating the pupil for fundus examination. Van Herick’s test is a quick method to estimate the depth of the peripheral chamber. Inform patients if they take antidepressant drugs or sympathomimetic over-the-counter drugs in case they have nar-

Inhibitors

Selective serotonin reuptake inhibitors are used as antidepressants. They increase the blood levels of serotonin causing mild mydriasis.

anterior chamber. A prophylactic Nd:YAG iridotomy will avoid a pupillary block. In cases without pupillary block the medications have to be stopped.

11.2.5Other Drugs Without Pupillary Block

Cholinergic drugs such as pilocarpine, especially at higher concentrations (4%), will thicken the

Bibliography

Fraunfelder FT, Fraunfelder FW (2001) Drug-induced ocular side effects. Butterworth Heinemann, Boston Lachkar Y, Bouassida W (2007) Drug-induced acute

angle closure glaucoma. Curr Opin Ophthalmol 18: 129–133