Which condition is most likely diagnosed in an 82-year-old man presenting with confusion and visual hallucinations after surgery?

In older adults, particularly following surgery or significant changes in their health status, the acute onset of confusion and visual hallucinations is most indicative of delirium. Delirium is characterized by an abrupt change in cognition or attention and is often precipitated by factors such as medications, dehydration, infections, or metabolic imbalances, which are common in a postoperative context.

In this scenario, the 82-year-old man's presentation after surgery aligns well with the typical features of delirium. The confusion and visual hallucinations suggest an altered mental state that can occur suddenly, distinguishing it from other more chronic conditions such as dementia diseases.

While conditions like dementia with Lewy bodies or Alzheimer's disease can present with confusion and visual hallucinations, they usually have a more insidious onset and involve long-term cognitive decline. Meanwhile, mania typically presents with a different symptomatology, including euphoria, irritability, and increased activity, rather than confusion and hallucinations after surgery.

Therefore, the presence of acute confusion and visual hallucinations in the context of recent surgery strongly supports a diagnosis of delirium as the most likely condition.