Laser scanning in vivo confocal microscopy of corneal microstructure in inherited and acquired corneal disease

Abstract

Purpose The cornea requires maintenance of clarity, shape, thickness and surface cellular integrity to retain normal vision. In vivo confocal microscopy (IVCM) enables microstructural analysis of the in vivo cornea, allowing fresh insight into corneal microstructure in health and in inherited and acquired corneal disease. Recently, the introduction of laser scanning IVCM has utilised point scanning with coherent light to push forward the boundaries of real-time in vivo imaging. This related series of studies aimed first to validate the role of laser scanning IVCM and then to utilise laser scanning IVCM to examine corneal microstructure in normal subjects, following penetrating keratoplasty and in corneal ectasia and corneal dystrophy. Methods Subjects were assessed with slit lamp examination, corneal topography and laser scanning IVCM. Basal epithelial, sub-basal nerve plexus, keratocyte and endothelial cell and innervation density were quantified. Results Laser scanning IVCM generated high quality images of corneal microstructure. Comparison with slit scanning confocal microscopy illustrated good correlation between the two microscopes, although differences existed between optical section thickness and image contrast. High repeatability and inter-session and inter-observer reproducibility was demonstrated with laser scanning IVCM. The subsequent studies examined corneal microstructure alterations with age, following penetrating keratoplasty, and in corneal ectasia and corneal dystrophy. Laser scanning IVCM highlighted alterations at every level of the cornea and good agreement was observed between the in vivo and ex vivo results following penetrating keratoplasty. Conclusions In vivo confocal microscopy allows rapid analysis of corneal microstructure in health and disease, offering clinicians and researchers an exciting bridge between clinical and laboratory observations.