Which of the following services is NOT covered by Medicare Part B?

Medicare Part B primarily covers medically necessary services and preventive items. Routine vision care, which typically includes services like eye exams for glasses and contact lenses, is not included as a covered benefit under Medicare Part B. This is significant as it emphasizes Medicare's role in providing coverage for significant health concerns rather than routine or basic care, which is often left to supplemental insurance plans or individuals to cover out of pocket.

In contrast, emergency room visits, preventive services, and physical therapy are covered under Medicare Part B. Emergency room visits are considered necessary services that might be critical for immediate healthcare needs. Preventive services, such as screenings and vaccinations, are also included to promote health and well-being, while physical therapy is covered when it is part of a treatment plan for a medically necessary condition. This distinction illustrates how Medicare Part B is structured to address specific healthcare needs rather than general or routine care.