In primary angle-closure glaucoma (PACG), the mechanism of plateau iris configuration differs from pupillary block in which way?
- A Plateau iris results from anteriorly positioned ciliary processes physically holding the peripheral iris against the trabecular meshwork even after peripheral iridotomy; pupillary block results from iris-lens contact impeding aqueous flow through the pupil ✓
- B Plateau iris is due to large lens size pushing the iris forward; pupillary block results from ciliary body forward rotation
- C Plateau iris causes bilateral simultaneous acute angle closure; pupillary block is always unilateral
- D Plateau iris requires goniotomy for treatment; pupillary block requires laser iridotomy
Explanation
Pupillary block (the most common mechanism in PACG) involves relative blockage of aqueous flow through the pupil due to iris-lens apposition, causing IOP buildup behind the iris, bowing it forward (iris bombé), and closing the angle. Laser peripheral iridotomy (LPI) relieves pupillary block by creating an alternate aqueous pathway. In plateau iris configuration/syndrome, anteriorly rotated ciliary processes physically push the peripheral iris against the trabecular meshwork; the angle remains occludable despite patent PI. Plateau iris requires argon laser peripheral iridoplasty (ALPI), not just PI.
Reference: Khurana Comprehensive Ophthalmology, 7th ed.
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Written and medically reviewed by the StethoPrep medical team.