In Vivo Confocal Microscopy of Corneal Grafts Shortly after Penetrating Keratoplasty

Abstract

Purpose

To describe the microstructural status of corneal grafts shortly after penetrating keratoplasty (PK) and to evaluate the efficacy and safety of confocal microscopy in examining corneal grafts at that time.

Methods

A confocal microscope with a 40x front lens was used to examine corneal grafts in 32 patients (32 eyes) 4 days after PK. Images were analyzed, and endothelial cell density counts were compared with presurgical, eye bank values determined by specular microscopy.

Results

Microstructural alterations of the graft included epithelial and stromal edema, epithelial degeneration in both superficial and basal cell layers, dark stromal striae, activated keratocytes, and needle-like structures in the stroma. Descemet membrane folds were visible in 31 of 32 grafts; in 1 graft, the dense stromal edema did not allow imaging of posterior layers. Stromal nerve fibers were imaged in 28 grafts (88%). Endothelial cell density ranged from 1666 to 2548 cells/mm² (mean±SD, 2125±283 cells/mm²); perioperative endothelial cell density loss varied from 0% to 29% (mean, 12%). No adverse reactions or signs of worsening of clinical condition were observed after the examination.

Conclusions

White light scanning slit confocal microscopy permits imaging of a graft's microstructure (including epithelium and stromal layers), as well as calculation of endothelium cell density, as soon as 4 days after PK. The most frequently observed morphologic alterations of corneal grafts shortly after PK include epithelial and stromal edema, epithelial degeneration, stromal striae, and Descemet membrane folds. Stromal nerves can still be seen in the graft 4 days after PK.