A 58-year-old hyperopic woman from Delhi presents to the emergency department with sudden onset of severe left eye pain, blurred vision, and nausea for the past 4 hours. She reports seeing halos around lights. On examination, the left eye shows corneal edema, mid-dilated pupil (5 mm), and intraocular pressure of 58 mmHg. Gonioscopy reveals an occluded angle. The right eye appears normal with IOP 16 mmHg and open angles on gonioscopy. What is the most appropriate immediate management?