Role of Medications in Angle Closure
In predisposed eyes with shallow anterior chambers, either mydriatic or miotic agents can precipitate acute angle closure. Mydriatic agents include not only dilating drops but also systemic medications with sympathomimetic or anticholinergic activity that may cause mild pupillary dilation. The effect of miotics is to pull the peripheral iris away from the anterior chamber angle. However, strong miotics may also cause the zonular fibers of the lens to relax, allowing the lens–iris interface to move forward. Furthermore, their use results in greater iris–lens contact, thus potentially increasing pupillary block. For these reasons, miotics, especially the cholinesterase inhibitors, may induce or worsen angle closure. Gonioscopy should be repeated soon after miotic drugs are administered to patients with narrow angles.
Systemic drugs with adrenergic (sympathomimetic) or anticholinergic (parasympatholytic) activity have the potential to cause angle closure. They include
allergy and cold medications
bronchodilator medications (for asthma and chronic obstructive pulmonary disease) such as ipratropium bromide and tiotropium bromide
antidepressants, anxiolytics, and antipsychotics
selective serotonin reuptake inhibitors (SSRIs) such as fluoxetine and paroxetine
tricyclic antidepressants such as amitriptyline and imipramine
antihistamine-anxiolytics such as hydroxyzine
phenothiazines such as chlorpromazine
antispasmodics used in urology such as tolterodine and oxybutynin
muscle relaxants such as orphenadrine and trihexyphenidyl
antinausea mediations, including promethazine
Although systemic administration generally does not raise intraocular drug levels as much as topical administration, even slight mydriasis in a patient with a critically narrow angle can induce angle closure. When such drugs are administered to patients with potentially occludable angles, it is important to inform the patient of the risk and consider iridotomy.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.