A 55-year-old patient with primary angle-closure suspect status undergoes provocative testing. The prone-darkroom test is performed. Which finding constitutes a positive result indicating significant pupillary block susceptibility?

• A IOP rise of 2 mmHg or more from baseline after 60 minutes in darkness and prone position
• B IOP rise of 5 mmHg or more from baseline after 60 minutes in darkness and prone position
• C Development of iris bombe without any IOP change
• D IOP rise of 8 mmHg or more from baseline after 60 minutes in darkness and prone position ✓

Explanation

A positive prone-darkroom test is defined as an IOP rise of 8 mmHg or more after 60 minutes in the dark in the prone position. This physiological test induces mydriasis and forward shift of the lens-iris diaphragm, provoking pupillary block in susceptible eyes. Smaller pressure rises are considered equivocal.

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

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