A 65-year-old woman with narrow-angle glaucoma presents to ophthalmology for routine examination. She is accidentally instilled with tropicamide 1% eye drops. Within 30 minutes, she develops severe eye pain, blurred vision, and photophobia. Vital signs: BP 158/92 mmHg, HR 102/min, RR 18/min. Intraocular pressure is measured at 55 mmHg in the affected eye. Slit-lamp examination reveals a mid-dilated, fixed pupil at approximately 6 mm. Gonioscopy confirms angle closure. She denies nausea or vomiting. Her baseline intraocular pressure was 18 mmHg at her last visit. Which mechanism explains this acute crisis?
- A)Nicotinic agonism causing pupillary constriction paradoxically
- B)Direct inhibition of carbonic anhydrase in the ciliary body
- C)Muscarinic antagonism causing mydriasis and angle closureGABARITO
- D)Beta-1 blockade reducing aqueous humor outflow
- E)Alpha-adrenergic stimulation causing iris ischemia
Explicação
Tropicamide is a muscarinic antagonist (anticholinergic) that causes mydriasis (pupil dilation). In narrow-angle glaucoma, mydriasis pushes the lens-iris diaphragm forward, narrowing the anterior chamber angle and obstructing aqueous humor outflow, causing acu... Ver explicação completa e trilha adaptativa →