Primary Open-Angle Glaucoma (POAG) Spectrum Practice Test

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.