Which of the following conditions requires immediate medical attention?

Closed angle glaucoma is a condition that requires immediate medical attention because it can lead to rapid vision loss due to a sudden increase in intraocular pressure. This occurs when the drainage angle of the eye, where the iris meets the cornea, becomes blocked, preventing aqueous fluid from draining normally. The sudden accumulation of pressure can result in severe pain, nausea, vomiting, and can cause permanent damage to the optic nerve if not treated quickly.

While open angle glaucoma is also a serious condition, it typically progresses slowly and is usually asymptomatic in its early stages, allowing for earlier intervention through regular eye exams. Papilledema, which involves swelling of the optic disc due to increased intracranial pressure, can indicate serious underlying conditions and should be evaluated, but it may not require immediate treatment as urgently as closed angle glaucoma. The white reflex, or leukocoria, is a symptom often associated with conditions like retinoblastoma or cataracts and also calls for prompt evaluation, but does not present the same acute risk of loss of vision as closed angle glaucoma does.

In summary, the need for swift medical response in closed angle glaucoma, due to its acute nature and the imminent threat it poses to vision, makes it the critical condition requiring immediate medical attention.