Light and Specular Microscopy Assessment of the Cornea for Grafting

Abstract

A detailed microscopic assessment of corneal quality is a crucial step in determining the suitability of a cornea for grafting. This chapter describes in detail the assessment of quantitative and qualitative corneal/endothelial parameters and their irregularities as observed by light and specular microscopy, together with links to images presented in the atlas (see Chap. 6). Endothelial cell density, the most important quantitative parameter of corneas intended for grafting, should generally be at least 2000 cells/mm2. In this regard, the detection of dead endothelial cells is important for preventing the overestimation of endothelial cell density. Polymegethism (variation in cell size) and pleomorphism (variation in cell shape), two basic qualitative morphologic parameters of the endothelium, together with the presence of Descemet membrane folds, cornea guttata, intracellular changes, and foreign bodies or precipitates are also assessed. The tissue should also be checked for the presence of severe epithelial defects or stromal opacities as signs of various stromal pathologies. In addition to initial cornea quality, changes affecting stored corneas or alterations arising as a consequence of the preparation of various types of endothelial lamellae may influence the quality and survival of a graft. Corneal alterations characteristic of certain corneal pathologies (endothelial dystrophies) that may be seen during the microscopic assessment of a donor cornea are described and linked to images of corneal explants (light microscopy) or patients’ corneas (specular microscopy) in the atlas.