Anticholinergic Medications and Pupillary Dilation

Clinical Applications and Side Effects

The American Academy of Otolaryngology-Head and Neck Surgery notes that scopolamine, a centrally acting anticholinergic, can suppress acute vertigo attacks but also causes pupillary dilation, with side effects including blurring of vision, dry mouth, dilated pupils, urinary retention, and sedation 1
According to the American Academy of Ophthalmology, adequate cycloplegia is necessary for accurate retinoscopic refraction in children, and anticholinergic medications can cause pupillary dilation and cycloplegia, facilitating examination of the optic disc, macula, retina, vessels, and choroid 2, 3
The American Academy of Ophthalmology also warns that anticholinergic agents can precipitate acute angle-closure glaucoma in susceptible individuals with narrow iridocorneal angles, and patients with primary angle-closure suspect (PACS) should be warned that anticholinergic medications could cause pupil dilation and induce acute angle-closure 4, 5

The American Academy of Ophthalmology notes that systemic side effects of anticholinergic agents include fever, dry mouth, rapid pulse, nausea, vomiting, flushing, somnolence, and rarely behavioral changes 3

Phenothiazines, such as promethazine, prochlorperazine, and chlorpromazine, possess anticholinergic effects that can cause pupillary dilation, as noted by the American Gastroenterological Association 6

Mydriatic eye drops (e.g., tropicamide, cyclopentolate, atropine, phenylephrine) directly produce pupil dilation and loss of light reactivity during and after an acute angle‑closure crisis. 7

Any anticholinergic or adrenergic medication can precipitate acute angle‑closure glaucoma in individuals with narrow iridocorneal angles. 7
Inhaled anticholinergic or adrenergic agents such as ipratropium bromide and salbutamol‑containing inhalers are capable of triggering acute angle‑closure glaucoma. 7
Sulfonamide antibiotics and the anticonvulsant topiramate can cause ciliary body edema, leading to acute angle‑closure glaucoma. 7

During an acute angle‑closure episode, pupils may appear mid‑dilated, asymmetric, or oval and often show poor or absent light reactivity. 7
After resolution of an acute angle‑closure event, pupils may remain non‑reactive despite normalization of intra‑ocular pressure. 7