Microcirculation plays an essential role in interaction between blood and target tissues. Despite its evident importance in pathophysiology and development of numerous acute and chronic deseases such as hypertension, diabetes or sepsis, current available methods allowing direct visualization of microcirculatory network and its assessment in clinical practice are very limited.
Orthogonal polarization spectral (OPS) imaging and its improved successor Sidestream dark-field (SDF) imaging are relatively new optical noninvasive technologies incorporated in hand-held examinating probe for visualization of mucosal surface microcirculation including human sublingual area. Basic principles of these methods, validation studies assessment, current possibilities of experimental and clinical applications and advantages with technical limitations are discussed in this review.