Acetazolamide decreases intraocular pressure by what mechanism: September 2010
**Core Concept**
Acetazolamide, a carbonic anhydrase inhibitor, is used to treat conditions like glaucoma by reducing intraocular pressure. It achieves this by inhibiting the enzyme carbonic anhydrase, which plays a crucial role in the production of aqueous humor.
**Why the Correct Answer is Right**
Acetazolamide works by inhibiting carbonic anhydrase in the ciliary body, which leads to a decrease in the production of aqueous humor. This reduction in aqueous humor production results in a decrease in intraocular pressure. Carbonic anhydrase is involved in the bicarbonate buffering system, and its inhibition disrupts the production of bicarbonate ions, leading to a decrease in the production of aqueous humor.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to the mechanism of action of acetazolamide. Acetazolamide does not work by increasing the outflow of aqueous humor, as it does not affect the trabecular meshwork or the uveoscleral pathway.
**Option B:** This option is incorrect as it suggests that acetazolamide works by reducing the production of aqueous humor through a different mechanism. However, the actual mechanism involves the inhibition of carbonic anhydrase.
**Option C:** This option is incorrect as it suggests that acetazolamide works by increasing the outflow of aqueous humor, which is not the case. Acetazolamide only affects the production of aqueous humor.
**Clinical Pearl / High-Yield Fact**
Carbonic anhydrase inhibitors like acetazolamide can cause a range of systemic side effects, including metabolic acidosis, electrolyte imbalances, and hypokalemia. It's essential to monitor patients for these side effects, especially in cases of prolonged use.
**Correct Answer: C. Decreasing the production of aqueous humor by inhibiting carbonic anhydrase.**