Glaucoma Eye Drops: Exam Guide
Learn glaucoma eye drops by class, mechanism and exam traps, including first-line prostaglandins, timolol contraindications and brimonidine risks.
In an uncomplicated patient with newly diagnosed primary open-angle glaucoma, which medication class is commonly chosen as initial monotherapy because of strong efficacy and once-daily dosing?
Glaucoma Eye Drops in 30 Seconds
Glaucoma eye drops lower intraocular pressure by targeting different parts of aqueous humor dynamics. The drug class matters on exams because the mechanism predicts the best choice, the main adverse effects and the key contraindications.
The Drug Classes
- Prostaglandin analogs (e.g. latanoprost): increase uveoscleral outflow. They remain the preferred first-line medication for many patients, although selective laser trabeculoplasty is now also an accepted first-line treatment. Dosed once nightly, as more frequent dosing does not improve and may reduce efficacy.
- Beta-blockers (e.g. timolol): suppress aqueous production. Generally contraindicated in asthma, severe COPD, sinus bradycardia and second- or third-degree AV block because systemic absorption can produce clinically significant cardiopulmonary effects.
- Alpha-2 agonists (e.g. brimonidine): reduce aqueous production and increase uveoscleral outflow. Avoid in infants due to CNS depression risk. Allergic follicular conjunctivitis is a common side effect.
- Carbonic anhydrase inhibitors (e.g. dorzolamide): suppress aqueous production by inhibiting carbonic anhydrase in the ciliary epithelium. A common non-beta-blocker option. Causes burning, stinging and a bitter taste.
- Rho kinase inhibitors (e.g. netarsudil): increase trabecular outflow and reduce episcleral venous pressure. This dual mechanism is a common exam target. Conjunctival hyperemia is the most prominent side effect.
5 Facts Exams Always Ask
- Prostaglandin analogs are first-line because they produce the greatest IOP reduction, roughly 25 to 35 percent, and are dosed once daily at night.
- Topical beta-blockers are contraindicated in asthma, severe COPD, sinus bradycardia and second- or third-degree AV block due to systemic absorption.
- Brimonidine must be avoided in infants because systemic absorption causes CNS depression and apnea.
- Prostaglandin analogs cause iris pigmentation, eyelash growth and prostaglandin-associated periorbitopathy, all board favorites.
- Netarsudil targets trabecular outflow and episcleral venous pressure, a dual mechanism that distinguishes it from all other classes.
The Classic Trap
The most common trap is mixing mechanisms across classes. Timolol suppresses aqueous production and does not increase outflow. Brimonidine is not a pure aqueous suppressant as it also enhances uveoscleral drainage. Exam questions are often built from a correct drug name attached to the wrong pathway. Always match drug to mechanism before selecting a contraindication or predicting a side effect.
Clinical Pearl
Prostaglandin analogs sit at the top of most treatment algorithms because they combine the greatest IOP reduction with once-nightly dosing, maximizing adherence. When a second agent is needed, combining a drug that increases outflow (prostaglandin) with one that suppresses production (beta-blocker or CAI) gives additive benefit because the mechanisms are complementary.
Checkpoint 1
Which patient history is the strongest contraindication to topical timolol use?
Checkpoint 2
Topical brimonidine should generally be avoided in infants and very young children because of risk of:
A 58-year-old with primary open-angle glaucoma needs a new drop. He has poorly controlled asthma and a resting pulse of 52. The resident proposes timolol because it is inexpensive. You review the chart and flag the choice. Which drug class is contraindicated here and why?
Which glaucoma medication class most commonly causes increased iris pigmentation and periocular skin darkening over time?
Sources & Reviewer Info
Diagram created with AI image generation, clinically reviewed for accuracy.
References
- American Academy of Ophthalmology. Basic and Clinical Science Course, Section 10: Glaucoma.
- Shields' Textbook of Glaucoma.
- American Academy of Ophthalmology. EyeWiki: Glaucoma Medications.
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