In the management of primary angle-closure glaucoma, laser peripheral iridotomy is performed. What is the fundamental mechanism by which this procedure relieves pupillary block?

• A It creates a hole in the trabecular meshwork, bypassing the drainage system
• B It contracts the ciliary muscle, opening the trabecular meshwork
• C It destroys ciliary body epithelium, reducing aqueous production
• D It allows aqueous to flow directly from posterior to anterior chamber, equalizing pressure across the iris ✓

Explanation

Laser peripheral iridotomy creates a full-thickness hole in the peripheral iris, allowing aqueous humour to flow directly from the posterior to the anterior chamber. This equalizes the pressure gradient across the iris, eliminating iris bombe and opening the drainage angle in pupillary block. It does not act on the trabecular meshwork or ciliary body.

Reference: Shields' Textbook of Glaucoma, 6th ed.

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