Effect of Ephedrine on Intraocular Pressure
Ephedrine is contraindicated in patients at risk of increased intraocular pressure, particularly those with glaucoma or narrow angles, as it can precipitate acute angle-closure glaucoma through its sympathomimetic effects causing pupillary dilation. 1
Mechanism of Action and Risk
Ephedrine acts as an α-adrenergic agonist with sympathomimetic properties that can cause mydriasis (pupillary dilation), which reduces aqueous humor outflow through the trabecular meshwork in susceptible eyes 2
The pupillary dilation induced by sympathomimetic agents like ephedrine can lead to pupillary block, precipitating acute angle-closure glaucoma—a true ocular emergency 3
This mechanism is particularly dangerous in patients with anatomically narrow angles, where mydriasis can physically obstruct the drainage angle 2
Clinical Evidence and Contraindications
Ephedrine is explicitly listed among drugs that have the potential to precipitate acute angle-closure glaucoma attacks in intensive care settings, alongside other sympathomimetic agents like adrenaline and atropine 3
The 2017 ACC/AHA Hypertension Guidelines specifically state that ephedrine is contraindicated in patients at risk of increased intraocular pressure (glaucoma) 1
High-risk patients include those with narrow angles on gonioscopy, family history of glaucoma, or pre-existing elevated IOP 2
Comparison with Related Sympathomimetic Agents
Other sympathomimetic decongestants like pseudoephedrine should also be used with caution in glaucoma patients due to similar mechanisms 4
Topical epinephrine (a related catecholamine) has been shown to reduce IOP in some glaucoma patients through prostaglandin-mediated mechanisms, but this is a distinct pharmacologic effect from systemic ephedrine 5, 6
Phenylephrine, another sympathomimetic, can cause transient IOP elevation through mechanisms unrelated to episcleral venous pressure 7
Critical Clinical Pitfalls
The most dangerous scenario is using ephedrine in undiagnosed narrow-angle glaucoma, where the first presentation may be acute vision-threatening angle closure 3
Patients receiving ephedrine in ICU settings or perioperatively should be monitored for acute vision changes, eye pain, or headache—cardinal symptoms of acute angle-closure glaucoma 3
Gonioscopy should be performed to assess angle anatomy before using sympathomimetic agents in at-risk patients 2
Absolute Contraindications
- Known angle-closure glaucoma 2
- Increased intraocular pressure 1, 2
- Patients at risk of increased intraocular pressure 1