In vivo corneal microscopy: from image to insight - where are we going?

In vivo confocal microscopy (IVCM) enables noninvasive imaging of the human cornea at cellular resolution, making it an indispensable diagnostic tool in clinical ophthalmology and biomedical research. The combination of the Heidelberg Retina Tomograph (HRT) and the Rostock Cornea Module (RCM) has established itself as the gold standard for corneal cellular imaging. This review summarizes the imaging principles, technological advancements, and clinical applications of IVCM. It highlights recent advancements, including automated large-area mosaicking of the subbasal nerve plexus, three-dimensional volumetric imaging, time-lapse imaging, and enhanced image analysis techniques. Additionally, corneal immune cell dynamics, critical to understanding corneal pathophysiology, are highlighted. Future challenges and developments aimed at improving diagnostic accuracy and clinical applicability are discussed.