Which of the following is the most reliable provocative test for angle closure glaucoma: September 2005
**Core Concept**
Angle closure glaucoma is a type of glaucoma characterized by the obstruction of the trabecular meshwork by the iris, leading to increased intraocular pressure (IOP). The diagnosis of angle closure glaucoma often requires provocative testing to induce the condition.
**Why the Correct Answer is Right**
The most reliable provocative test for angle closure glaucoma is the **dark room test**, also known as the **pupil dilation test**. This test involves dilating the pupils with a mydriatic agent, such as tropicamide, and then observing the patient in a dark room. The test is reliable because it allows for the assessment of the anterior chamber angle in a state of maximum mydriasis, increasing the likelihood of angle closure. The test is particularly useful in patients with narrow angles, as it can help identify those at risk of angle closure.
**Why Each Wrong Option is Incorrect**
* **Option A:** The **swinging flash light test** is used to assess for a relative afferent pupillary defect, not angle closure glaucoma.
* **Option B:** The **gonioscopy** is a direct visualization technique used to examine the anterior chamber angle, but it is not a provocative test.
* **Option C:** The **water drinking test** is used to assess for orthostatic hypotension, not angle closure glaucoma.
**Clinical Pearl / High-Yield Fact**
The dark room test should be performed with caution in patients with narrow angles, as it can precipitate angle closure.
**Correct Answer: C. Dark room test**