Fixed combinations without beta blockers result in a ________% IOP reduction.

• A. 10-20%
• B. 21-35%
• C. 30%
• D. 35-50%

Answer: (B)

Fixed combinations without beta blockers typically give a moderate drop in IOP because they pair two different mechanisms to lower aqueous humor dynamics. Prostaglandin analogs mainly increase outflow through the uveoscleral pathway, while other agents in these combos—such as carbonic anhydrase inhibitors or alpha-2 agonists—reduce production. When two distinct actions are combined, the effect on lowering IOP tends to be additive but not extreme, landing in a mid-range reduction. Clinically, this constellation of actions commonly yields roughly a 21–35% reduction from baseline, which is why that range best matches the expected effect of fixed-dose combinations that do not include a beta blocker. Higher reductions (approaching 35–50%) are more typical of combinations with beta blockers or more potent regimens, and very modest reductions (10–20%) are less characteristic of these fixed, two-mechanism regimens.