Virtual microscopy: past, present and future

Virtual microscopy is a simulation of real microscopy, using virtual slides displayed on a computer screen. A virtual slide is created by capturing and assembling digital images of sequential microscopic fields, to produce a large, composite image of an area of a real glass slide. Compared to real slides, virtual slides are easy to store, retrieve, duplicate or distribute and do not deteriorate over time. In recent years, virtual microscopy has been tested in a range of activities in pathology, including education, quality assurance, proficiency testing and secondary consults. Recently, virtual slide scanners that use oil immersion lenses have enabled the creation of high resolution virtual slides of blood and bone marrow specimens. This development has facilitated the use of virtual slides in morphology education and quality assurance in haematology. Key questions are whether virtual slides can be diagnostically equivalent to real slides, and how image quality may be standardised. Such issues will determine the extent to which virtual slides may be applied to activities such as education, quality assurance, proficiency testing, secondary consults, and primary diagnosis in haematology.