Irvine-based Quality Systems, which develops healthcare information systems, said today that it is in an agreement to acquire Opus Healthcare Solutions, a provider of web-based, clinical information systems. Financial details of the buy were not disclosed. According to Quality Systems, it will combine Opus Healthcare Solutions with Sphere Health Systems, which it acquired in August of 2009, as part of its NextGen Healthcare Information Systems subsidiary. Opus provides electronic health record (EHR) software for health clinics.