Beta blockers added to prostaglandin analogs for glaucoma provide an additional intraocular pressure reduction of how many mmHg?

• A. 1-2 mmHg
• B. 4-6 mmHg
• C. 2-3 mmHg
• D. 0-1 mmHg

Answer: (C)

When two glaucoma medications with different mechanisms are used together, their effects on lowering intraocular pressure tend to add up, but the extra drop from adding a beta-blocker to a prostaglandin analog is modest. Prostaglandin analogs primarily increase outflow of aqueous humor, producing a substantial initial reduction. The beta-blocker primarily reduces production of aqueous humor, giving a smaller, additional decrease when added to the prostaglandin regimen. On average, this incremental reduction is about 2-3 mmHg. So the best answer reflects this typical, modest extra drop: a 2-3 mmHg additional reduction. Variability exists among patients, but 2-3 mmHg is the commonly observed range.