A medical diagnostic instrument or a plurality of disparate medical diagnostic instruments are configured with a common optical architecture that functionally creates a virtual eye to create closer proximity to a patient and therefore increase the field of view in regard to a target of interest. The optical system includes a distal optical element, at least one relay lens and an eyepiece lens in which the optical system can be integrated within at least one instrument or be provided using a releasable module. Additionally, at least one of a viewing assembly and illumination assembly of at least one medical diagnostic instrument can be assembled using a series of components that are connected by interlocking features.
