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 available for clinical use.

In vivo confocal microscopy (IVCM), a non-invasive method for the microscopic imaging of the living tissues, has been used for the investigation of the corneal microstructure since the early 1990s,1 2 and confocal imaging has increasingly evolved from the level of experimental use in laboratory investigations to the application in the clinical setting in healthy and diseased patients.3 4 A review of the scientific production in this field highlights the fact that IVCM has been widely used to investigate the in vivo microstructure of the living cornea and to detect changes and abnormalities in a huge variety of corneal pathologies (ie, infections, dystrophies and dry eye) or following surgery, as well as an in vivo method for detection of drug toxicity on the ocular surface.5^–17 For the first time in the history of ophthalmology, confocal microscopy now provides clinicians and researchers with a direct view of …