What is a hallmark symptom of acute angle closure glaucoma?

The hallmark symptom of acute angle closure glaucoma is the sudden onset of eye pain. This condition occurs when the drainage angle between the iris and cornea becomes blocked, leading to a rapid increase in intraocular pressure. Patients typically experience intense, piercing pain in the affected eye, which can be accompanied by other symptoms such as nausea, vomiting, and visual disturbances (like halos around lights).

The mechanism behind the pain involves the tension on the structures in the eye and the rapid increase in pressure, which triggers discomfort and can result in a medical emergency if not treated promptly. Recognizing this sudden, severe eye pain is critical for promptly diagnosing and managing acute angle closure glaucoma to prevent permanent vision loss.