Which topical medication lowers aqueous humor production by inhibiting carbonic anhydrase?

• A. Dorzolamide
• B. Brinzolamide
• C. Acetazolamide
• D. Methazolamide

Answer: (A)

Topical carbonic anhydrase inhibitors reduce aqueous humor production by blocking the enzyme carbonic anhydrase in the ciliary body. This decreases formation of bicarbonate and the associated ion and water transport into the eye, leading to less aqueous humor being produced and lower intraocular pressure. Dorzolamide is a topical CA inhibitor given as eye drops, directly targeting the site of production to achieve this effect. (Note: other topical options exist, like brinzolamide, which work by the same mechanism, while acetazolamide and methazolamide are systemic CA inhibitors used orally.) Therefore, dorzolamide is the topical agent that lowers aqueous humor production by inhibiting carbonic anhydrase.