A 65-year-old woman presents with decreased vision, headache, and severe eye pain. Ophthalmic examination reveals a dilated right pupil and increased intraocular pressure. What is the most likely diagnosis?

The presented symptoms and findings strongly suggest a diagnosis of angle-closure glaucoma. The key indicators include decreased vision, headache, severe eye pain, a dilated pupil, and increased intraocular pressure.

In angle-closure glaucoma, the fluid drainage angle of the eye becomes obstructed, leading to a rapid increase in intraocular pressure. This can present acutely, often accompanied by severe eye pain and headache due to the pressure buildup. The dilated pupil is also characteristic, as the autonomic nervous system's response to elevated pressure can result in a pupil that is non-reactive and remains dilated.

Acute uveitis could present with eye pain and vision changes; however, it typically doesn't cause a dilated pupil or a significant increase in intraocular pressure in the same acute manner as angle-closure. Corneal abrasion might cause eye pain and can lead to tearing and redness, but it wouldn't typically be associated with a dilated pupil or elevated intraocular pressure. Open-angle glaucoma usually presents more gradually and typically does not feature the acute symptoms or presentation seen in this case.

Thus, the combination of the acute presentation, the specific symptoms, and the examination findings strongly support a diagnosis of angle-closure glaucoma.