We read with interest the published perspective article entitled “Confocal Microscopy in Ophthalmology,” by Erie and associates. They briefly described the principles and characteristics of the different in vivo confocal microscopes, and they discussed the limited clinical and research applications of this technology. We would like to add additional information and a different perspective to this discussion.

For the first time in the history of ophthalmology, confocal microscopy now provides clinicians and researchers with a direct view of the corneal cells and tissues in the living eye. Concerning the corneal cellular changes, the authors focused on keratocyte density after surgery and in keratoconus. In vivo confocal microscopy also is useful in the study of noninfectious inflammatory processes associated with, for example, dry eye or atopic keratoconjunctivitis. In these disorders, changes in corneal cell density, principally keratocytes but also epithelial cells, are associated with the abnormal presence of inflammatory cells, including dendritic cells and activated keratocytes. The observation by confocal microscopy of these cellular components and their changes associated with clinical history or treatments is a potentially interesting research application.

Inflammatory or toxic processes also involve the subbasal nerve plexus. Nerve density is probably the most easily quantifiable and most described feature. Nevertheless, other characteristics, such as fiber tortuosity and formation of bead-like structures, contribute to a better understanding of the pathogenic mechanisms in which neurodegenerative and regenerative changes are overlapping.

Finally, we would like to emphasize different applications of the laser scanning confocal microscope. In addition to the cornea, this instrument is able to examine the bulbar and tarsal conjunctiva and the meibomian glands. We are looking forward to the opportunity to study the ocular surface by in vivo confocal microscopy. The cornea and associated tissues form a morphofunctional unit. In this unit, the physiologic and pathologic processes may be understood better through integration of the information obtained by simultaneous optical sampling of its different components.