In vivo confocal microscopy of the ocular surface: where are we now?
Until recent times, the universally diffused diagnostic tool for the imaging of the cornea and ocular surface had been based on traditional slit-lamp biomicroscopy, with or without the aid of stains. The exponential technological evolution that occurred during the last two decades has led to the introduction of new instruments such as corneal topography, ultrasound biomicroscopy (UBM) and optical coherence tomography (OCT) for the analysis of the anterior segment. These techniques provide details on corneal curvature or macroscopic cross-sections of the examined structures. In contrast, the microscopic morphology of the ocular surface tissues could be assessed only by ex vivo histology (presenting limitations due to tissue degeneration, artefacts and impossibility of evaluating over time an evolving disease process) and by the aid of impression cytology which is, however, based on a limited sampling of superficial epithelial layers, since the development of in vivo confocal microscopes
