Research in schema evolution has been driven by the need for more effective software development and maintenance. Finding impacts of schema changes on the applications and presenting them in an appropriate way are particularly challenging. We have developed a tool that finds impacts of schema changes on applications in object-oriented systems. This tool displays components (packages, classes, interfaces, methods and fields) of a database application system as a graph. Components potentially affected by a change are indicated by changing the shape of the boxes representing those components. We have evaluated the tool by own judgement on a real-life application and by a controlled student experiment. Our results indicate that identifying impacts at the level of fields and methods can reduce the time needed to conduct schema changes and reduce the number of errors compared with identifying impacts at the level of classes. Moreover, the subjects of the experiment appreciated the idea of visualizing the impacts of schema changes.