What MOST likely causes angle-closure glaucoma in a patient?

Angle-closure glaucoma, also known as acute glaucoma, occurs when the drainage angle of the eye becomes blocked, leading to a sudden increase in intraocular pressure. This condition is characterized by a rapid elevation of pressure, resulting in severe pain, blurred vision, nausea, and vomiting. It can occur in individuals with a narrow anterior chamber angle or those whose pupils dilate in low-light conditions, causing the iris to narrow further and block the drainage pathways through which aqueous humor exits the eye.

The other options represent processes that may impact the eye but do not directly cause acute angle-closure glaucoma. Hardening of the lens or lens clouding typically refers to conditions like presbyopia or cataracts, which do not lead to the sudden pressure increase associated with angle-closure glaucoma. Similarly, while gradual onset of increased intraocular pressure is related to open-angle glaucoma, it does not describe the acute, sudden nature of angle-closure glaucoma that is elicited by immediate blockage of the drainage angle. Therefore, the sudden increase in intraocular pressure is the most accurate description of what causes angle-closure glaucoma.