Which pilocarpine concentration is typically used after an acute angle-closure attack to make the iris taut for Laser Peripheral Iridotomy?

• A. 0.125%
• B. 1%
• C. 5%
• D. 2%

Answer: (D)

To perform Laser Peripheral Iridotomy effectively, you want the peripheral iris to become taut so the laser can reach the iris plane cleanly. Pilocarpine is used to induce miosis, which pulls the iris away from the cornea and trabecular meshwork, widening the angle. After an acute angle-closure attack, the iris is often edematous and the chamber shallow, so you start with IOP-lowering measures and once the eye begins to respond, you use a mid-range pilocarpine concentration to achieve reliable miosis without excessive side effects. A 2% pilocarpine solution tends to give consistent, rapid constriction of the pupil in this setting, providing the needed iris tautness for a safe and successful LPI. Lower strengths may not produce enough miosis in an edematous, ischemic iris, while a higher strength like 5% is usually unnecessary and increases the risk of adverse effects such as ciliary spasm or systemic symptoms.