Contrast-enhanced micro-CT for visualization of cell distribution in hydrated human cornea

The human eye’s cornea is vital for visual clarity and quality of life. Besides proteoglycans, an adequate hydration contributes to a transparent cornea by uniform distribution of collagen fibrils. Understanding the cell distribution within the multi-layered cornea is fundamental to investigate corneal physiology and pathology. Micro-CT imaging potentially enables a spatial examination of the cornea. This study employs contrast-enhanced micro-CT to demonstrate the feasibility and expectable precision of X-ray imaging of the intricate multi-layered human cornea. Human donor corneas were hydrated to different degrees, mimicking the in-vivo state of edema formation. Tissue samples were then immersed in Lugol’s iodine for contrast enhancement and scanned by the laboratory micro-CT Skyscan 2211. The effects in the soft tissue contrast were evaluated accordingly. The contrast-to-noise ratios (CNR) for the cell layers, specifically the epithelium and endothelium, were 8.67 ± 1.17 and 5.84 ± 0.53, respectively. In comparison, the stromal tissue exhibited a significantly lower CNR of 1.81 ± 0.29. This discrepancy highlights Lugol's iodine's strong affinity for binding cells, which enhanced the contrast of individual stromal cells relative to the surrounding collagen fibrils, and the potential to be visualized with contrast-enhanced micro-CT. The present study underscores the potential of contrast-enhanced micro-CT for soft tissue applications with multi-laminar ultrastructure. This advanced imaging technique might enhance our understanding of corneal biology and its applications in clinical settings. Additionally, the specific binding properties of Lugol’s iodine demonstrated may extend to other biological samples and thus opens new pathways for virtual/3D histology.