Review Article In Vivo Laser Scanning Confocal Microscopy of Human Meibomian Glands in Aging and Ocular Surface Diseases

Meibomian glands (MGs) play a crucial role in the ocular surface homeostasis by providing lipids to the superficial tear film.Their dysfunction destabilizes the tear film leading to a progressive loss of the ocular surface equilibrium and increasing the risk for dry eye. In fact, nowadays, the meibomian gland dysfunction is one of the leading causes of dry eye. Over the past decades, MGs have beenmainly studied by usingmeibography, which, however, cannot image the glandular structure at a cellular level.The diffusion of the in vivo laser scanning confocal microscopy (LSCM) provided a new approach for the structural assessment of MGs permitting a major step in the noninvasive evaluation of these structures. LSCM is capable of showingMGsmodifications during aging and in themost diffuse ocular surface diseases such as dry eye, allergy, and autoimmune conditions and in the drug-induced ocular surface disease. On the other hand, LSCMmay help clinicians in monitoring the tissue response to therapy. In this review, we summarized the current knowledge about the role of in vivo LSCM in the assessment ofMGs during aging and in the most diffuse ocular surface diseases.