ABO Ophthalmology Complete Practice Exam 2025

Angle-closure glaucoma is characterized by a sudden increase in intraocular pressure, which is primarily triggered by the blockage of the drainage angle of the eye. This blockage occurs when the iris is pushed or pulled forward into the angle of the anterior chamber, preventing the aqueous humor from draining effectively through the trabecular meshwork. As a result, the intraocular pressure rises sharply, leading to acute symptoms associated with angle-closure glaucoma, such as severe eye pain, headache, nausea, and visual disturbances.

This mechanism is distinct from other types of glaucoma. For example, gradual blockage of the drainage angle occurs over time in open-angle glaucoma, where the drainage channels become less efficient but do not cause an immediate rise in pressure like in angle-closure glaucoma. While genetic predisposition can play a role in a person's risk for developing various types of glaucoma, it does not directly cause the acute events seen in angle-closure cases. Similarly, infections can lead to other complications in the eye but are not causative factors for angle-closure glaucoma. Therefore, the correct understanding of angle-closure glaucoma points to the sudden rise in intraocular pressure due to obstruction at the drainage angle as the primary causal factor.