A 65-year-old woman presents to the ED with sudden onset of right eye pain and blurred vision. Physical examination reveals circumcorneal injection, a 7 mm right pupil that is unresponsive to light and an intraocular pressure of 35 mm Hg. Which of the following is the gold standard test to confirm the diagnosis?
A. Dark room provocation
B. Dilated fundus examination
C. Gonioscopy
D. Slit lamp grading