A 50-year-old hypermetropic woman with narrow angles on gonioscopy but normal IOP, open visual fields, and no synechiae undergoes a provocative test in which she sits in a darkened room with pupils dilated for one hour. A positive test is defined as:

• A A rise of IOP by more than 6 mmHg from baseline
• B A rise of IOP by more than 8 mmHg from baseline ✓
• C Any measurable rise in IOP regardless of magnitude
• D Development of a relative afferent pupillary defect

Explanation

The dark room test exploits physiological mydriasis in darkness, which increases relative pupillary block and can precipitate angle closure in predisposed eyes. A positive result is conventionally taken as an IOP rise exceeding 8 mmHg above baseline after one hour in the dark, often confirmed with gonioscopy showing closure. A smaller rise of 5 to 6 mmHg is used in some other provocative variants, so knowing the accepted cutoff matters. The test has largely been superseded by gonioscopy and OCT assessment but remains examinable.

Reference: Parson's Diseases of the Eye / Khurana Comprehensive Ophthalmology, Latest Indian editions ed.

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Written and medically reviewed by the StethoPrep medical team.