Glaucoma refers to a group of eye conditions that damage the optic nerve. This damage often results from elevated pressure inside the eye, known as intraocular pressure (IOP). This pressure typically builds when the eye’s internal fluid, called aqueous humor, does not drain properly. While various factors contribute to glaucoma development, certain medications can induce or worsen the condition.
How Medications Can Induce Glaucoma
Medications can affect the eye’s internal fluid dynamics, leading to increased intraocular pressure through two primary mechanisms: affecting the open-angle drainage system or causing angle-closure. In open-angle glaucoma, medications can reduce the outflow of aqueous humor through the trabecular meshwork, the eye’s primary drainage system. This reduced outflow leads to a buildup of fluid, causing pressure to rise gradually inside the eye.
Angle-closure glaucoma involves a physical blockage of the eye’s drainage angle. Medications can cause this through pupillary block, where the pupil dilates and the iris (the colored part of the eye) presses against the lens, preventing fluid flow and forcing the iris forward to close off the drainage angle. Another mechanism involves the swelling of structures behind the iris, such as the ciliary body or choroid. This swelling can push the lens-iris diaphragm forward, blocking the drainage angle, even in eyes without a naturally narrow angle.
Common Medication Classes Linked to Glaucoma
Several classes of medications affect intraocular pressure and can contribute to or worsen glaucoma. Corticosteroids are associated with open-angle glaucoma. These medications, used in various forms such as oral tablets, inhaled sprays, topical eye drops, skin creams, and injections, can elevate eye pressure. They increase the resistance to aqueous humor outflow by impacting the trabecular meshwork. The risk of pressure elevation increases with the dosage and duration of corticosteroid use.
Anticholinergic medications can also pose a risk, primarily by inducing angle-closure glaucoma. These drugs are found in various treatments, including those for overactive bladder, irritable bowel syndrome, certain psychiatric conditions, and some cold and allergy remedies. Their mechanism involves causing pupillary dilation, which can lead to pupillary block, especially in individuals with pre-existing narrow drainage angles.
Sulfa-containing drugs, such as topiramate (used for migraines and epilepsy) and certain diuretics or antibiotics, can uniquely trigger acute angle-closure glaucoma. These medications can cause the ciliary body and choroid to swell, pushing the lens and iris forward and blocking the eye’s drainage system. This reaction can be bilateral and may occur even in eyes that do not have a naturally narrow angle.
Other medications can also contribute to glaucoma risk, particularly angle-closure. These include certain antidepressants like SSRIs and tricyclics, some antihistamines, and sympathomimetic drugs often found in cold remedies and bronchodilators. These drugs commonly induce pupillary dilation, which can precipitate angle-closure in susceptible individuals.
Patient Considerations and Risk Management
Individuals should inform their healthcare providers about all medications they are taking, including over-the-counter drugs and supplements. This comprehensive disclosure helps medical professionals assess potential risks to eye health. Regular eye examinations are also important, particularly for those using medications known to affect intraocular pressure or for individuals with pre-existing risk factors for glaucoma. These risk factors can include a family history of glaucoma, naturally narrow eye angles, farsightedness, advanced age, or certain ethnicities such as Asian, Inuit, or Hispanic backgrounds.
Patients should be aware of symptoms that might indicate medication-induced glaucoma, especially acute angle-closure. These symptoms can include sudden eye pain, redness, blurred vision, seeing halos around lights, headache, or nausea and vomiting. If these symptoms appear, immediate medical attention is necessary. It is important that patients never stop taking prescribed medications without first consulting their doctor, as abruptly discontinuing treatment can have adverse health consequences.
An individual’s susceptibility to medication-induced glaucoma can be influenced by factors such as the medication’s dosage, the duration of its use, and their unique biological predisposition. Understanding these interactions allows for proactive management and helps protect vision.